Food Engineering
Mohammad Reza Salahi; Seyed Mohammad Ali Razavi; Mohebbat Mohebbi
Abstract
Introduction: Emulsion-filled gel is a sort of gel system that traps oil droplets as a filler and contains a wide range of semi-solid to solid food products. They can also be utilized as a dual system to distribute and control the release of both lipophilic and hydrophilic bioactive and micronutrient ...
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Introduction: Emulsion-filled gel is a sort of gel system that traps oil droplets as a filler and contains a wide range of semi-solid to solid food products. They can also be utilized as a dual system to distribute and control the release of both lipophilic and hydrophilic bioactive and micronutrient substances. The main polymers involved in gel formation in food products are proteins and polysaccharides. Using molecular interactions between biopolymers, a wide range of rheological and physicochemical properties of gels can be methodically created. As a result, the interaction between proteins and polysaccharides has received a lot of attention in order to generate novel products. Because of their functional qualities and high nutritional value, whey proteins are frequently used in the food industry. As a result, mixed gels based on whey protein have gained a lot of attention. k-Carrageenan is commonly utilized in the food industry as a gelling and firming agent. Because k-Carrageenan, like whey protein isolate, can form a gel independently, its interaction with whey protein isolate in emulsion gel systems appears appealing. Therefore, in this study, the effect of k-Carrageenan gum (0.0, 0.1, 0.3, 0.5, and 0.7%) on the textural (uniaxial compression test), rheological (steady shear, strain sweep, and frequency sweep tests), and water holding capacity of cold-set emulsion-filled gel based on whey protein isolate was investigated.Materials and Methods: Whey protein isolate (WPI) (98.9% protein, dry basis) was given as a gift by Agropur Ingredients Co. (Le Sueur, Minnesota, USA). k-Carrageenan and CaCl2 (m_w: 147.01 gr/mol) were purchased from Sigma Aldrich Co. (USA) and Merck Co. (Darmstadt, Germany), respectively. Sunflower oil was bought from a local supermarket. Stock dispersions of WPI and k-Carrageenan were made by dissolving sufficient amounts of their powders in deionized water. To prepare uniform oil in water emulsion, sunflower oil was added to the WPI dispersion and the obtained mixture homogenized first using a laboratory rotor-stator homogenizer (15000 rpm, 3 min), then by an ultrasonic homogenizer (20 kHz, 5 min). The prepared emulsion and k-Carrageenan dispersions were poured into Schott bottles and heated in a water bath (90 C, 40 min). WPI emulsion and AG dispersion were mixed in a cylindrical container on a stirring plate at a speed of 600 rpm for 6-8 min to obtain a homogeneous mixture. After decreasing the temperature to 60 C for the ion-induced gelation, the mixtures were charged with CaCl2 (10 mM). The prepared samples were incubated in a refrigerator overnight to stabilize the 3D network. The final mixed EFG samples contained 5.5% WPI, 20% oil, and 0, 0.1, 0.3, 0.5, and 0.7% (w/w) of k-carrageenan. The tests performed on emulsion-filled gel samples were: 1) steady shear (0.01-10 s-1), 2) strain sweep (strain: 0.1-1000%, frequency: 1 Hz), 3) frequency sweep (frequency: 0.1-100 Hz, strain: 0.5%), 4) uniaxial compression (target strain: 80%, deformation speed:1 mm/s), and 5) water holding capacity (by utilizing a microcentrifuge, 600×g for 10 min).Results and Discussion: According to the steady shear test, all samples had a shear thinning behavior, and based on the power-law model, this behavior was intensified in the presence of k-Carrageenan; and with increasing the gum concentration from 0 to 0.7%, the consistency coefficient increased from 339.9 to 545.7 Pa.s. In the strain sweep test, with the increase in the gum concentration, the values of the elastic and viscous modulus in the linear region and the modulus at the crossover point increased, and Tan LVE decreased from 0.17 to 0.13, which indicated an increase in the strength of the emulsion gel network structure. Based on the frequency sweep test, with the increase in k-Carrageenan concentration, the parameters K^' and K^'', network strength and network expansion, respectively, increased from 5311.8 Pa, 939.9 Pa, 1.5380 Pa.s1/z and 10.05 in the control sample to 25080 Pa, 3574.9 Pa, 16097.7 Pa.s1/z and 16.41 in the sample containing 0.7% k-Carrageenan, respectively. Moreover, the frequency dependency of elastic modulus decreased from 0.095 in the control sample to 0.050 in the 0.7% k-Carrageenan contained sample. According to the large deformation test, in general, in the composite emulsion-filled gels, the values of apparent modulus of elasticity and fracture stress were higher and fracture strain and fracture energy were lower than in the control sample. Also, the results showed that different k-Carrageenan concentrations had no significant effect on the water holding capacity.The obtained results showed that k-Carrageenan had considerable influence on the rheo-mechanical features of cold-set emulsion-filled gels based on whey protein which can add to the knowledge base for the production of new functional foods.
Food Engineering
Mosatfa Soleymani; Vahid Hakimzadeh; Mostafa Shahidi Noghabi; Akram Arianfar
Abstract
IntroductionAppropriate and effective decolorization of raw and thin juice in sugar refineries is considered as an important process to obtain premium quality sugar, which due to the problems of its conventional process, membrane processes as effective and environmentally friendly processes can be used ...
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IntroductionAppropriate and effective decolorization of raw and thin juice in sugar refineries is considered as an important process to obtain premium quality sugar, which due to the problems of its conventional process, membrane processes as effective and environmentally friendly processes can be used in parts of sugar industries. Among the disadvantages of the usual methods to remove membrane fouling, it can be mentioned the destruction of the membrane, environmental pollution, the remaining detergents in the membrane and the product, especially in the pharmaceutical and food industries, and the increase in production costs. Therefore, it seems that physical methods such as pre-filtration of the incoming feed, using turbulent and pulse currents to prevent excessive compression of the gel layer formed on the membrane surface are more effective and have fewer disadvantages. One of the ways to change the flow of feed entering the membrane surface is bubbling, which causes mixing the flow and increases the tangential shear stress. In fact, the hydrodynamic force that creates bubbles causes both the dragging force and the lifting force and leads to the removal of fouling and reducing the phenomenon of concentration polarization. Materials and Methods In this research, an ultrafiltration membrane (MWCO=10 KDa) pilot with a flat module (effective surface 40 square centimeters) was used to purify raw beet juice (which had passed a stage of pre-treatment with microfiltration) at the temperature of about 30 degrees Celsius and a trans membrane pressure of 3.5 bar during the process. Nitrogen gas in the amount of 0.5, 1 and 1.5 liters per minute was used in two continuous and interrupted modes for bubbling. In this way, in the interrupted mode, after every 3 minutes of filtration, the filtration process was carried out with gas for one minute. The factors such as flux, fouling and membrane resistance as membrane efficiency's factors and parameters like color, purity and turbidity as purification factors was investigated in the form of a completely random design and compared with control filtration conditions (without bubble generation). The results of this research were statistically analyzed using SAS (version 1.9) and Microsoft Office Excel 2019 software. The average data of each test in three repetitions was compared with the least significant difference (LSD) test at the 95% level. Results and DiscussionIncreasing the amount of gas during the bubbling process improved the flow rate. Also, the results showed that the decreasing trend of the permeate flux at the gassing rate of 1.5 L/min was less than other treatments and more stable conditions were seen in the sap flux during the process. Also, the amount of flux in the interrupted form of bubbling showed that after the application of bubbling, although the amount of flux increased, but after that, during the ultra-refining process, the flux decreased again and did not remain constant at that level. But in general, despite the fact that the average flux was higher in the continuous process compared to the interrupted state, there was no significant difference between them. The results related to the amount of membrane fouling after applying the process showed that by applying bubble generation in both continuous and interrupted mods, the fouling was significantly reduced compared to the usual state of ultrafiltration. Also, as the amount of gas entering the feed stream increased, the membrane fouling decreased, which was slightly higher in the continuous state than in the interrupted mod. The overall hydrodynamic resistance of the membrane in different filtration modes showed that the difference between the overall resistance of the membrane in the ultrafiltration and the ultrafiltration process with gasification is quite significant. However, although the overall resistance of the membrane in the interrupted gassing state is higher than its continuous state due to more clogging, there is no significant difference between them (P<0.05).Since the flux changes and the amount of gel layer formation affect the properties of the purified syrup, the properties of the syrup were also investigated in the best flux created in two continuous and interrupted modes. The results showed that the continuous flow of gasification caused a small defect in the purification properties such as purity, color and turbidity due to the improvement of the permeate flow flux, which of course can be ignored in the sugar industry due to the improvement of the permeate flow flux. ConclusionTherefore, in general, it can be said that the discontinuous method, due to less gas consumption during bubbling and no significant difference in the amount of flux compared to the continuous mode, can be considered as the optimal mode of gasification during the experiments conducted in this research be placed.
Food Engineering
Saeede Hamidi; Nafiseh Zamindar; Nayyere Gholipour Shahraki
Abstract
IntroductionThermal processing is an important method of canned food production (Farid & Abdul Ghani, 2004). Estimation of the heat transfer rates is essential to obtain optimum processing conditions and to improve product quality. In addition, a better understanding of the mechanism of the heating ...
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IntroductionThermal processing is an important method of canned food production (Farid & Abdul Ghani, 2004). Estimation of the heat transfer rates is essential to obtain optimum processing conditions and to improve product quality. In addition, a better understanding of the mechanism of the heating process will lead to an improved performance in the process and to some energy savings (Abdul Ghani et al., 1999). Computational fluid dynamics (CFD) is an efficient way to study flow behavior and temperature distribution of thermal processing in the food technology (Ghani et al., 2003). As the semi-rigid aluminum packaging market recently has been introduced, there is limited information about the temperature distribution during the heating process of such containers. In this paper the temperature distribution was predicted and location of cold zone was determined. The effect of headspace (air and water vapor) in heat transfer mechanism was investigated. Materials and MethodsPhysical propertiesMalt extract properties such as density, specific heat, thermal conductivity and viscosity values are necessary for the equations solution. Viscosity and density of the sample was measured as a function of temperature (Vatankhah et al., 2015). Specific heat and thermal conductivity of sample were estimated using the mass fraction of its constituents. For simulation, the experimental results were applied by piecewise-linear method in the material part of the software to describe viscosity, thermal conductivity and specific heat. Experimental methodologyFor the experimental, a thermocouple probe was located at point (0, 0, -2.76) in a semi rigid aluminum based packaging to measure the temperature distribution inside the container. Then the package was filled with malt extract (°Brix ~ 60) and then the package was sealed at 280 °C using Alcan machine. Another thermocouple was placed near the containers, in the water cascading Barriquand steriflow retort. The thermocouples were attached to Ellab data logger by PT100 cables. The data logger was connected to a personal computer and E-val 2.1 software was used to export time temperature profile of each thermocouple in 1 min intervals. Geometry and meshingGambit 2.3.30 was used to develop geometry and set of grid (0.2 cm, and 0.1 cm mesh size) was performed. Then software of fluent 6.3.26 with 3-D, double precision, pressure-based solver, implicit formulation, unsteady time, laminar flow was applied to solve the system of the governing equations (Vatankhah et al., 2015). Boundary conditions and initial valuesUnsteady temperature function was imposed to all faces of the geometry in 1 min time intervals. No-slip boundary condition was supposed for velocity components relative to boundaries. The boundary conditions used at top surface, bottom surface and side walls included: T = Tw, Vx = 0, Vy = 0 and Vz = 0. The initial temperature was assumed as the first temperature which was measured by the thermocouple at the starting time of processing. Solution methodologyFluent software was used to solve the Navier-Stokes and energy equations simultaneously. A preset convergence limit of 10−3 for continuity and momentum equations and 10−8 for the energy equation were used, in order to achieve an appropriate convergence. The under-relaxation factors were adjusted smaller than 1 to obtain a good convergence of the numerical solution. SIMPLEC algorithm was used for pressure-velocity coupling. Results and DiscussionThere was no significant difference between predicted and experimental temperatures for point (0, 0, -2.76) in models with and without head space using t-test (p<0.01). Temperature contours of predicted models (with headspace) were similar to model without headspace at the different stages of the process. Simulation result showed slowest heating zone located in (0.02 <X< 0.8, -1 <Y< 0.3 and -3.27<Z< 3.27) for model of malt extract with headspace and in (-3.58 < X< 3.76, -3.44 <Y< 0.48 and -3.46 <Z< -3.05) for model of malt extract without headspace. ConclusionThe heating process of malt extract in semi rigid aluminum container during thermal processing was simulated successfully using CFD. The CFD based model showed that the position of SHZ was located in the third end of the container.
Food Engineering
Seyed Mohammad Ali Razavi; Morteza Kashaninejad
Abstract
Introduction Ultrafiltration is one of the most common membrane processes in the dairy industry, especially for condensing and separating milk components. Using this process, several products can be produced, including milk concentrate used for cheese production, low-lactose dairy products, milk ...
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Introduction Ultrafiltration is one of the most common membrane processes in the dairy industry, especially for condensing and separating milk components. Using this process, several products can be produced, including milk concentrate used for cheese production, low-lactose dairy products, milk protein concentrate, and serum proteins for dietary supplements. The efficiency and cost of a membrane process depend on the percentage of rejection of the soluble components. Therefore, the use of concentrated milk made by ultrafiltration in the production of various dairy products depends on the efficiency of the membrane process and the changes in milk components during this process. On the one hand, the physicochemical properties of camel milk are different from those of cow milk, especially in terms of type and amount of protein. Because significant differences exist between the physicochemical properties of camel and cow milk, likely, the membrane processing conditions and the physicochemical properties of their products will be different completely. Although many studies have been conducted on the efficacy of the ultrafiltration processing of cow milk, there is no information about the efficacy of camel milk ultrafiltration, and most of the research done regarding optimizing is based on classical algorithms, Therefore, in this study, the effects of transmembrane pressure and temperature on the solutes rejection (protein, lactose, ash, and total solids) during camel milk ultrafiltration process were investigated, Then, these properties were optimized using particle swarm algorithm. Also, because the performance of the particle swarm algorithm is highly dependent on related parameters such as the number of iterations, the number of particles, accelerate constant, inertia weight, and velocity of the particles, so before optimization, the effect of these parameters on optimal responses were examined by partial least squares regression (PLS). Materials and Methods In this study, a pilot crossflow ultrafiltration system was used. A UF membrane (Model 3838 HFK-131, Koch membrane systems, Inc., USA) made of polysulfone amid (PSA) with MWCO of 20 kDa was applied. Camel milk was purchased from a local market in Mashhad and for camel skim milk production, its fat was separated by a pilot plant milk fat separator in the Food Research Complex, Ferdowsi University of Mashhad. The weight percentages of protein, fat, lactose, ash, and total solids of UF permeate samples were measured by ISO 8968-1:2014, ISO 1211: 2010, ISO 26462/IDF 214:2010, ISO 5544:2008, and ISO 6731:2010 at two replications, respectively. the process treatments were performed in the form of a central composite design (CCD) (5 replications at the central point) for two independent variables at three levels so that the total number of 13 treatments was obtained. The data were modeled using the statistical software of Design Expert (version 11) based on the response surface methodology and each of the response variables in the form of a regression model was presented as a function of independent variables. Results and Discussion The rejection of total solids and protein of the tested samples varied in the range of 45.4-51.03% and 94.09-97.51%, respectively. It means that in each TMP and T, more than 45% of the total solids and 94% of the protein of camel milk were kept by the membrane. The results also showed that none of the linear, quadratic and interactive effects of TMP and T on the total solids and protein rejections were not significant. According to the results, the RL reduced with increasing T. Increasing the TMP also led to a reduction at high T and an increase in RL rate of the samples at lover T. Also, the effect of TMP on RA showed a non-linear trend, so that TMP at high T led to an increase, and at low T, it led to a reduction in the RA of the samples. Conclusion The optimization results with the particle swarm algorithm showed that this algorithm has a high convergence speed and by recognizing and analyzing its parameters, the optimal conditions can be easily found. The optimum ultrafiltration conditions in this study with the lowest RL and RA were determined as 80 kPa TMP and 29.85 ͦ C T.
Food Engineering
Sima Yassari; Hossein Mirsaeedghazi; Leila Roozbeh Nasiraie; Ali Fadavi
Abstract
IntroductionAs a useful fruit for humans, apple (Malus domestica) is a good sourceof antioxidants, minerals, ascorbic acid, vitamins, polyphenols, fibers and other essential elements with medicinal properties. Improving the storage time of apple juice and maintaining the stability of extracts with high ...
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IntroductionAs a useful fruit for humans, apple (Malus domestica) is a good sourceof antioxidants, minerals, ascorbic acid, vitamins, polyphenols, fibers and other essential elements with medicinal properties. Improving the storage time of apple juice and maintaining the stability of extracts with high Brix value (during transportation and storage) and its marketability by removing the remaining water as well as reducing the turbidity, viscosity and brown color caused by colloidal suspended solids. Large (pectin, protopectin, pigments, polymeric carbohydrates, tannin, starch, cellulose, hemicellulose, fibers, etc.) is of great importance. Due to the presence of colloidal suspended solid particles and compounds that settle over time (mold, bacteria, plant cell fragments, pectin-tannin complex), apple juice must be clarified before concentration. Due to the high-energy consumption, time-consuming, degradation of thermo-sensitive components, and reduction of nutritional value in traditional methods, recently, the use of membrane concentration in food and beverage production holds great potential.. Despite all the benefits of membrane processes, one of the critical problems is permeate flux decline due to the concentration polarization and membrane fouling. In this study, an innovative mechanical motion was developed to remove the cake deposits on the membrane surface towards mitigating adverse effects of polarization and fouling. Materials and MethodsMembrane scraped surface module was designed and made with polyethylene material. The membrane was enclosed between the lower and upper parts of the module. These two parts are connected with screws and create a cylindrical part. Also, two caps are pressed axially to this cylindrical part by a metal frame to eliminate any unwanted leakage. The rotor shaft was coupled with an electric motor and the rotation of the output shaft was regulated by an inverter. A pump transferred the fresh fruit juice to the module through the inlet port and then it was divided into two output streams, permeate and retentate. The permeate was collected from the bottom of the module for further investigation and the retentate was returned to the juice tank. A polyethersulfone (PES) membrane with molecular weight cut-off (MWCO) of 4 kDa was used to clarify apple juice. Effects of the blade rotation speed (0, 600, 1400 and 2200 rpm), transmembrane pressure (TMP) (0.5, 1 and 1.5 bar), feed flow rate (FFR) (10, 15 and 20 ml/s) and the distance of the blade from the membrane surface (2 and 5 mm) on volumetric concentration factor (VCF) and fouling phenomenon were evaluated. Hermia model was used to study the main fouling mechanism and it was verified by scanning electron microscopy (SEM) images. Results and Discussion Results showed that rotating the blade with speed of 600 rpm at TMP of 0.5 bar, FFR of 10 ml/s and 2 mm distance from the membrane surface had the best performance in VCF and reducing fouling. The main mechanism of fouling was cake formation. Rotation of the blade decreases the intensity of cake formation and its thickness on the membrane surface and enhances the standard pore blocking. Also increasing the blade rotation speed changes the main fouling mechanism to the standard pore blocking due to the cake disintegration on the membrane surface and the penetration of fine particles into the membrane pores. As a result, the rotation of blade had a significant positive effect on increasing the VCF. On the other hand, the total resistance decreased with the rotation of the blade and by increasing the distance of blade from the membrane surface, the intensity of cake formation reduced. Also, the SEM images showed that in without blade rotation mode, the accumulation of cake particles on the membrane surface is thicker and denser than in with blade rotation mode. On the other hand, the low thickness of the cake layer formed on the membrane surface in the process of blade rotation is due to the turbulences resulting from the rotating blade. These observations confirm the results of the Hermia model in the previous sections. Conclusion In conclusion, the TMP 0.5 bar, FFR of 10 ml/s, blade rotation speed of 600 rpm with a distance of 2 mm from membrane surface were considered as the best conditions for ultrafiltration of apple juice using scraped-surface membrane unit.
Food Engineering
Javad Safari; Jafar Hashemi; Azadeh Ranjbar Nedamani
Abstract
Introduction Due to the importance of product appearance quality in product grading and the impact of factors such as area, uniformity, and various defects on the product quality, and also, the ability to recognize these features at a very low cost, image processing techniques, is one of the methods ...
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Introduction Due to the importance of product appearance quality in product grading and the impact of factors such as area, uniformity, and various defects on the product quality, and also, the ability to recognize these features at a very low cost, image processing techniques, is one of the methods used to evaluate food quality. Therefore, in this study, a non-destructive image processing method was used to investigate the factors affecting the color and shrinkage of apple slices during drying. Materials and Methods Golden delicious apples were used in this research. The central part of the apple (including the rivet, seeds, and tail) was removed by a kernel separator and sliced into 3, 5, and 7mm thickness and approximately 7 mm diameter slices using a hand slicer without separating the skin. Three temperatures of 60, 70, and 80 °C were used to dry the samples. To determine the moisture content of a sliced apple, the samples were first weighed on a digital scale, then placed in a dryer, and the experiment was continued until the samples reached equilibrium mass. Due to the high importance of moisture ratio in controlling the drying process, moisture rate (MR) and moisture content (MC) were calculated, and samples were taken to investigate the amount of surface shrinkage, general color changes and browning index. After extracting L*, a*, and b* values, total color changes and browning index (to show the intensity of brown color in the product) for all samples before and after drying were calculated and evaluated to describe color changes after drying. Results and Discussion The drying kinetics results showed that the drying process significantly depends on the thickness of the samples. According to drying curves, at the early stages of drying, the decrease in humidity occurs more severely and the graph has a steeper slope, but as the process continues and the moisture content of the product decreases, the slope of the curve decreases. In the early stages of drying, due to the presence of water inside the fresh fruit cells, there is a pressure balance between the fruit and the surrounding environment, which causes the fruit to remain swollen. However, as the drying time progressed, contractile stresses are created, which cause superficial shrinkage. In this study, it was observed that increasing the thickness from 3mm to 7mm, reduced the final shrinkage on the surface of apple slices by 11% at 60 °C, 12% at 70 °C, and 13% at 80 °C. After moisture leaves the surface of the product and heat penetrates into the product, moisture begins to leave the product by conducting interstitial convection. When moisture moves to the surface, the mechanical balance and consequently the textural structure of the sample is disturbed due to the creation of different spaces in thickness. According to the results, increasing drying time and thus decreasing the moisture content, increases the percentage of apple shrinkage. On the other hand, at a certain thickness, with increasing temperature, the percentage of shrinkage changes in the thickness of the product decreases. Therefore, at thicknesses of 3, 5, and 7 mm, the increase in temperature from 60°C to 80°C, decreased the amount of shrinkage thickness by 16, 12, and 8%, respectively. It is in higher thicknesses that react with heat and change the color of the fruit due to the Maillard reaction. After complete drying of apple samples, the highest amount of color change was related to the thickness of 7 mm and a temperature of 80°C, which was equal to 1.254. Also, the lowest rate of discoloration of apple slices in a thickness of 3 mm and a temperature of 60 °C was 0.889. The browning index (Bi) in the high thickness of apple slices is less affected by the process temperature due to the increase in moisture level. For this reason, the rate of browning was very low among the experimental samples and the highest rate of browning was related to the thickness of 7 mm and the temperature of 80 °C was 585/2559. Also, the lowest rate of browning of apple slices was observed in the thickness of 3 mm and the temperature of 60 °C was 584.254. Conclusion Finally, it was found that the thickness and temperature factors can have an effect on the quality of product during drying process. The results of this study can provide a cheap and fast way to control the quality of fruits during drying and help producers of these products select the main process factors that affect the final quality.
Food Engineering
Sajad Jafarzadeh; Mohsen Azadbakht; Faryal Varasteh; Mohammad Vahedi Torshizi
Abstract
Since persimmon is a pressure-sensitive fruit and it is difficult to store this fruit in warehouses, in this research, an attempt has been made to examine the parameters affecting the reduction of changes in its physical properties. The samples were loaded at 150 and 250 N, three types of foam container ...
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Since persimmon is a pressure-sensitive fruit and it is difficult to store this fruit in warehouses, in this research, an attempt has been made to examine the parameters affecting the reduction of changes in its physical properties. The samples were loaded at 150 and 250 N, three types of foam container packaging with polyolefin film, polyethylene-terephthalate, and ordinary box, and four types of polyamine putrescine coating with concentrations of 1 and 2 mM, distilled water and uncoated. Properties such as Physiological Weight Loss, volume, and the density of persimmon fruit, as well as the firmness of this fruit in the prepost-storage stage were examined. The results showed, the highest firmness was obtained in the treatment of putrescine at a concentration of 1 mM and a foam container with polyethylene film with a value of 6.5 N, which was almost three times the firmness of uncoated fruits. The lowest Physiological Weight Loss, volume, and density were obtained in the same type of coating and packaging. The values of these parameters were 2.458%, 1.82, and 0.833%, respectively, compared to the first day of storage. Overall, the use of polyamine treatment showed a significant effect on changes in the physical properties of persimmon fruit, and foam containers with polyolefin film emerged as the optimal packaging option, resulting in the least amount of change among the different types of packaging used.
Food Engineering
Setereh Ramezani; Mohammad Shahedi; Milad Fathi
Abstract
Global concern about human health and the increase the prevalence of chronic diseases in recent years lead to growing appeals for nutritious and healthy compounds, such as coenzyme Q10. Susceptibility to heat and lipophilic properties of coenzyme Q10 limit its utilization in food. Encapsulation is a ...
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Global concern about human health and the increase the prevalence of chronic diseases in recent years lead to growing appeals for nutritious and healthy compounds, such as coenzyme Q10. Susceptibility to heat and lipophilic properties of coenzyme Q10 limit its utilization in food. Encapsulation is a technology that protects bioactive ingredients from harsh environmental conditions and extends shelf life. The purpose of this study was to encapsulate coenzyme Q10 using complex coacervation by gelatin–basil seed mucilage and characterize physical, thermal and chemical properties of produced microcapsules. Response surface methodology was applied to determine the optimum level of the four formulation variables for maximum encapsulation efficiency, loading capacity and turbidity and minimum supernatant absorption. The optimum microcapsules had encapsulation efficiency of 83.69%, encapsulation load of 16.32%, turbidity of 0.979 and supernatant absorption of 0.227. The microcapsules were assessed by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The results of FTIR confirmed the formation of coacervates. The thermogram of Q10 loaded microcapsule melting point was not observed at its melting point (50°C) due to its solubility in the oil phase and appropriate entrapment. Release behavior of Q10 was studied by different mathematical models. Microencapsulated Q10 was used to fortify milk and the results showed that the developed protein-carbohydrate microcapsules can be applied for protection of hydrophobic compounds.
Food Engineering
Fatemeh Yousefzadeh; Masoud Taghizadeh
Abstract
Introduction
The consumption of milk and its products is considered as a main indicators of development of human societies. In order to promote the health of children and provide the sufficient amount of calcium and nutrients and make the consumption of these products attractive. Necessary measures ...
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Introduction
The consumption of milk and its products is considered as a main indicators of development of human societies. In order to promote the health of children and provide the sufficient amount of calcium and nutrients and make the consumption of these products attractive. Necessary measures should be taken to increase milk consumption in society and increase the diversity of these products (Keshtkaran et al., 2013). Gelatin as one of the gelling agents used in dairy desserts is a hydrocolloid with unique functional properties and has been used in various industries for a long time (Karim & Bhat, 2008). Gelatin is extracted from the partial hydrolysis of skin collagen, white connective tissue, and animal bones. One of the problems with using gelatin in dairy desserts is the instability at ambient temperature. Therefore, it is necessary to evaluate the characteristics of other native hydrocolloids as an alternative. Tragacanth is a dried gum secreted from several plant species and Iran is the largest exporter in the world. Structurally, the material is regular, odorless and hard. It can be used in various food products. The simultaneous utilization of hydrocolloid mixtures is used to create a synergistic property and to improve these products. Starch originated from a variety of sources , including corn, rice, wheat, potatoes, cassava, bananas, and sorghum (Murphy, 2000) is used in the food industry. Among the sources of starch production, wheat is cultivated in large quantities in Iran.
Materials and Methods
In this study, pasteurized milk was purchased from Salamat Dairy Products Company, gelatin made in Pakistan, tragacanth gum and Gonabad wheat starch were purchased from Kian Shimi Company and sugar and vanilla were purchased from confectionery stores located in Mashhad. Ingredients for dessert production include 80% milk, 10% sugar, 0.1% vanilla, tragacanth gum at concentrations of 1.3%, 1%, and 0.7% and starch at concentrations of 3% , 2%, and 1% by weight (powder selection) according to the method of Tarrega et al. 2004 with a slight modification. A sample containing 1.5% gelatin was considered as a control sample. The mixture was heated to 90 ° C for 20 minutes, stirring at medium speed. The samples were then placed in special containers and cooled to ambient temperature. Prior to testing, the samples were refrigerated (4-5 ° C) for 24 hours. The samples were coded based on the concentration of gum and starch (: T% of tragacanth gum and: S% of wheat starch).
Results and Discussion
The flow behavior in all dairy dessert samples was similar to the control and was pseudoplastic type. The Power model was selected as the best model (R <98, RMSE> 1.6). As the concentrations of tragacanth gum and wheat starch increased, the parameters of hardness, consistency, adhesion and adhesion strength increased significantly, and the samples 0.7T2S, 0.7T3S and 1T, 1S had the same value in terms of all textural parameters. At constant concentration of starch, with increasing tragacanth gum from 0.7% to 1.3%, the rate of syneresis of samples decreased from 0.34% to 0.06% and at constant concentration of gum, with increasing concentration of wheat starch, Syneresis decreased significantly from 0.34 to 0.24%. Increasing the shelf life of the samples naturally led to an increase in syneresis. In the samples 0.7T3S, 1T3S, 1T2S, and 1.3T3S, the increase of syneresis occurred to a lesser extent.. According to the results of analysis of variance, the effect of gum on zeta potential was very significant (p <0.05). Increasing the concentration of hydrocolloids in most samples led to an increase in the amount of negative charge and zeta potential. In most samples, at a constant concentration of tragacanth gum, with increasing the concentration of wheat starch from 1% to 3%, the span decreased, while at a constant concentration of starch, the increase in tragacanth gum from 0.7% 0 to 1.3% led to increase the span. Among the dairy dessert samples, 5 dairy dessert samples include: 0.7T2S, 0.7T3S, 0.7T1S, 1T2S and 1.3T1S, were selected the best in terms of physical and rheological characteristics to the control sample. They were more similar, selected and used for sensory evaluation. The results of comparing the mean of the data showed that different concentrations of tragacanth gum and wheat starch had a significant effect on the sensory characteristics of the samples including: color, flavor, sweetness, adhesion, gum state and overall acceptance (P> 0.05) and increasing the concentration of tragacanth gum and wheat starch had no significant effect on other sensory properties (p> 0.05).
Conclusion
In general, due to the similarities of the physical, rheological and sensory properties of the treatment samples with the control, 1S1T sample was selected as the most suitable sample to replace the sample containing gelatin.
Food Engineering
Elahe Dehghan; Behzad Mohammadi
Abstract
Introduction
Sesame paste is a product that is obtained by mixing Ardeh obtained from peeling of Sesame seeds with sugar or other sweeteners and flavorants such as cardamom and vanilla. Each 100 grams of this nutritious product contains 558 kcal and providing 17% of the daily calcium need, 100% ...
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Introduction
Sesame paste is a product that is obtained by mixing Ardeh obtained from peeling of Sesame seeds with sugar or other sweeteners and flavorants such as cardamom and vanilla. Each 100 grams of this nutritious product contains 558 kcal and providing 17% of the daily calcium need, 100% for iron and 26% for protein. Sesame cream /Ardeh cream provides 478 kcal per 100 grams. Ardeh cream is also a good alternative to chocolates with artificial colors, so it is a very good choice in cases of hypoglycemia, such as before the exam session of students or during heavy excersize such as mountaineering. Sugar substitutes are compounds that, like sugars, are used to sweeten foods, except that they are not digested without the need for metabolized insulin, or are digested sparingly and therefore have little caloric value. The diet products are usually based on reducing calorie intake, which today, the growing interest of people in eating healthy diet has led to an increase in their desire to consume low-calorie products. Patients with diseases caused by sugar consumption such as diabetes, hypertension and hyperlipidemia, osteoporosis, obesity, etc. tend to use artificial sweeteners such as saccharin, aspartame, cyclamate and acesulfame.
Materials and Methods
Hydrogenated oil, Skim milk powder, Whey powder, Soy lecithin, Potassium dichromate, Ethanol, Ardeh , Erythritol, Isomalt Powder, Ribodioside a, Sugar Stable micro histometer systems, Ballmer, Memmert model digital scale, Autoclave, Oven, N Hexane, Desiccator, Soxhlet device, 500 cc balloon, Peptone water, Dichlorine-Rose Bengal Chloramphenicol Agar (DG18), coax reagent, EC broth culture medium, lauryl sulfate culture medium, pH meter with measuring accuracy of 0.1%, 0.1 N sulfuric acid solution, Potassium sulfate, dioxide Selenium, boric acid solution, crystallized copper sulfate, aluminum plate were used in this study . First, to prepare a control sample, raw materials such as flour, oil and sugar were added to the mixer and mixed together, then the rest of the ingredients were added and mixed inside the machine to make the cream uniform and homogeneous. Then it was transferred to the filter and packed in the desired containers. Sugar substitutes were used for the rest of the samples.
Results and Discussion
The prevalence of obesity and diabetes has increased dramatically in recent years, forcing consumers to look for low-calorie sweeteners. Replacing low-calorie sweeteners with sucrose results in low-calorie, and healthy foods. The aim of this study was to present a new formulation using isomalt, ribadioside a, erythritol as sucrose substituents and to investigate its effect on chemical, physical and sensory properties of substituted samples compared to the control sample. The use of sucrose substituents was effective in improving some physicochemical properties of Ardeh so that the moisture content of the substituted samples increased. The results of histological examination also showed that the replaced samples had softer tissue than the control sample, which was due to the weakening of tissue stability by sucrose substitutes. The results of sensory properties based on aroma, taste, odor and texture also showed that sample 2 with the formula 25% sucrose, 6.25% isomalt, 0.003 ribodiozide obtained the highest score in terms of overall acceptance. The reason for the decrease in the general acceptance of the samples replaced with complete elimination of sucrose is the lack of regulation of the desired sweetness by these alternatives. The results of microbial analysis of samples also showed that sugar substitutes have no effect on the microbial properties of Ardeh. According to the obtained results, sample 2 with 25% sucrose, 6.25% isomalt, 0.003% ribodioside a is the best combination and a healthy and low calorie snack.
Food Engineering
Mohammad Khalilian-Movahhed; Mohebbat Mohebbi; Charlotte Sinding
Abstract
IntroductionEfforts have always been made to protect valuable compounds of medicine, food and aromatics materials that are highly sensitive to environmental conditions by the encapsulation method. encapsulation of flavors, in addition to its protection, allows the aromatic substance to be released in ...
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IntroductionEfforts have always been made to protect valuable compounds of medicine, food and aromatics materials that are highly sensitive to environmental conditions by the encapsulation method. encapsulation of flavors, in addition to its protection, allows the aromatic substance to be released in a long time, and the time and place of its release can be controlled. To design these protection systems requires detailed information on encapsulation and release methods, the nature of walls and aromatic materials (Gunning et al.,1999). For encapsulation of sensitive compounds such as lipophilic materials, it is necessary to produce an emulsion of the desired substance in wall materials such as proteins, polysaccharides or a mixture of them. The important factors in encapsulation are the molecular weight, chemical properties and polarity of the core materials, the properties of the materials of the walls, and finally, the methods used to produce microcapsules. (Jafari et al., 2008).The aim of this study was to produce and evaluate the properties of two and six layer multilayer microcapsules containing limonene using soy protein isolate and starch modified by spray drying. The release of encapsulated limonene was investigated under artificial oral conditions under different stress conditions. The results of this study can be used to predict the release rate of the encapsulated flavors and their release conditions.Materials and MethodsSolution preparation: The solution of SPI (0-3%) was prepared by methods of Huang et al. (2012). The OSA starch stock solution (0-2%) was prepared by methods of Nilsson and Bergens (2007).Emulsion’s preparation: the primary emulsion of the optimum SPI and secondary emulsion of optimum OSA starch concentration prepared by the method of Noshad et al (2015).Microcapsule production: To prepare the Microcapsules, a laboratory spray dryer was used. 180±5 ᵒC, inlet air temperature, 25 (ml/min) feed rate, and 90±10 ᵒC outlet air temperature were used. Six layer microcapsules was also prepared in the same conditions (Ansarifar et al., 2017)The micro structure, morphology and release of limonene were evaluated and finally by Zero order, First order, Higuchi, and Korsemeyer- peppas models were used to the fitting of experimental data.Limonene release: To investigate the release of the encapsulated limonene, the release of these microcapsules (two and six layer) at 37 ° C and pH = 6.8, as well as frequent chewing (0, 50 and 100 rpm) were examined. For the apply of shear stress, an oral simulator was designed and developed by the Department of Food Science and Technology of Ferdowsi University of Mashhad was used. Results and DiscusionThe results of particle size changes of the initial emulsion formed with different levels of soy protein isolate showed that the particle size decreased with increasing the concentration of this protein to 1.5% and then it was increased. The results of zeta potential showed that with increasing the concentration of soy protein isolate to 1.5%, the zeta potential of the samples increased and with more than 1.5%, it did not have much effect on the zeta potential of the samples, which indicates that concentrate of 1.5% soy protein isolate has a good ability to cover surface of limonene particles. Similarly, 1.2% of OSA starch was determined for the secondary layer.SEM images of the microcapsules showed that in the two-layer wall microcapsules have cavities, cracks and shrinkage. In the starting of drying, the rate of moisture lost is high and on the other hand, the wall is not strong enough to withstand the stresses caused by the exit of moisture from the walls, so the microcapsule has cavities. In six-layer microcapsules, a smooth, non-cracked surface was observed, which can be attributed to the wall strength due to the increase in the number of layers. Fourier transform infrared spectroscopic (FTIR) test showed that the outer surface of the microcapsules was covered by OSA starch in two and six layer microcapsules.The release profile of encapsulated limonene showed that the release rate in two layer samples was faster than six layer samples. Also, with increasing shear rate, the amount of release increased. The results of experimental models fitting showed that the first-order model had the best description for releasing limonene from two- and six-layer samples in different conditions. Calculation of diffusion coefficient showed that six-layer microcapsules have a lower diffusion coefficient than two-layer microcapsules, which leads to a decrease in the release rate of limonene.Conclusion The results of this study showed that the layer-by-layer method could be used to produce limonene microcapsules. Soy protein isolate and modified starch can cover limonene droplets well. SEM images showed that the structure of six-layer microcapsules is free of cracks and cavities and has a more uniform surface than two-layer microcapsules. To investigate the mechanism of limonene release from two- and six-layer microcapsules, different kinetic models were used to fit the experimental release data. The results showed that the release of these microcapsules occurred based on the diffusion mechanism and Fick's law, which is the main mechanism of mass transfer in the release process. Also, the results showed that the six-layer microcapsules had a lower diffusion coefficient than the two-layer microcapsules and the release rate was lower in the two-layer microcapsule; This is due to the repetitive coating of soy protein isolate and modified starch around the microcapsules and the increase in wall thickness.
Food Engineering
Fateme Mousavi Baygi; Arash Koocheki; Behrooz Ghorani; Mohebbat Mohebbi
Abstract
Introduction Curcumin, as a natural polyphenolic nutraceutical has been shown many health-promoting effects, mainly associated with its chemical structure. In various studies, different properties of this compound, including anti-tumor and anti-cancer activity, reduction of blood and liver cholesterol ...
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Introduction Curcumin, as a natural polyphenolic nutraceutical has been shown many health-promoting effects, mainly associated with its chemical structure. In various studies, different properties of this compound, including anti-tumor and anti-cancer activity, reduction of blood and liver cholesterol levels, increase of immune function, prevention of cardiovascular diseases, prevention of damage to biological membranes against peroxidation and anti-inflammatory properties have been reported. Despite possessing a potential health benefits to humans, the susceptibility of this polyphenol towards environmental conditions and low chemical stability has restricted the direct usage of curcumin into aqueous-based food formulations. The encapsulation of curcumin in liposomes is a potentially effective way to protect them from degradation during passing the digestive system.Materials and MethodsCurcumin (powder, purity greater than 99%, 368.38 g/mol), lecithin, cholesterol (C3045-25G), pancreacin (extracted from porcine pancreas, P7545-25G), bile salts (B8756-10G) and calcium chloride (CaCl2) was obtained from Sigma Aldrich (USA). Consumable ethanol was purchased from Pars Ethanol Company (96%, Iran). Lipase enzyme (extracted from pig pancreas, L8070) and pepsin (activity 3500-3000 NFU/g, P8390) were obtained from Solarabio (China). Potassium chloride, dipotassium hydrogen phosphate (K2HPO4) and alpha-amylase enzyme with a purity of at least 99% were obtained from Merck, Germany, sodium chloride (NaCl), sodium bicarbonate (NaHCO3) and calcium chloride were obtained from Sigma. The effect of lecithin content (0.02- 0.08 g), lecithin cholesterol ratio (0.5- 4), curcumin level (1.5- 6mg) and ultrasound treatment time (1-5 minutes) on production of liposomes containing curcumin was evaluated. The particle size, particle size distribution, zeta potential and efficiency were determined by response surface methodology. Furthermore, physical nature, molecular structure, physical stability at 4ºC and 25ºC and release behavior of curcumin loaded-liposome in mouth, stomach and intestines were explored.Results and Discussion The results showed that all independent variables had a significant effect on liposome particle size and increasing the ratio of lecithin: cholesterol caused more uniform particle size. Lecithin was determined to be the only component affecting the zeta potential of liposome particles, and increasing the ultrasound time increased the efficiency of curcumin encapsulation in liposomes. The optimal point of liposome preparation conditions in the amount of 0.08 g lecithin, 4: 1 the ratio of lecithin: cholesterol, 4.16 mg curcumin and 5 minutes the ultrasound treatment was introduced by Design Expert software. In addition, curcumin was amorphous in optimal liposome spherical particles. Furthermore, the results of TEM showed that the liposomes are in the form of single-layer particles, spherical and without membrane rupture. This makes the bilayered nature of the vesicles clearly visible in this micrograph. The size of the particles obtained from this method was consistent with the data obtained from the dynamic light scattering method. From the results of infrared spectroscopy, it can be seen that curcumin is trapped in the liposome through hydrogen bonding in the double-layered vesicle of the liposome, the phenolic ring of curcumin with the phospholipid head group, as well as the hydrophobic interactions of the aromatic rings with the acyl phospholipid chains. Liposomes were more stable at refrigeration temperature. A very small amount of curcumin was released in the simulated oral phase, which is probably due to the short time and lack of specific enzymes to disrupt the phospholipid bilayers of the liposome. Although the pepsin enzyme is unable to penetrate the liposome membrane, acidic conditions change the angle of the head and tail groups of the lipids and lead to a change in the surface charge of the liposomes. The release of curcumin from liposome vesicles was greatly increased in the intestine. This sudden increase is due to the presence of bile salts as an emulsifying agent that can disrupt the phospholipid membrane and make the membrane more fluid. In addition, pancreatic lipase is adsorbed on the surface of lipids and then hydrolyzes the phospholipid into 2-acyl and 1-acyl lysophospholipids and free fatty acids. The release behavior of curcumin under gastrointestinal conditions was based on the Fick mechanism.
Food Engineering
Ali Heydari; Masoud Goharimanesh; Mohammadreza Gharib; Ali Koochi
Abstract
Introduction
The beneficial use of ultrasonic systems has been proven in many applications. Among them, ultrasonic atomization is widely used in various industries, including food and coating industries. Ultrasonic vibrations of liquids can produce fine droplets called atomized fluid. During the fluid ...
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Introduction
The beneficial use of ultrasonic systems has been proven in many applications. Among them, ultrasonic atomization is widely used in various industries, including food and coating industries. Ultrasonic vibrations of liquids can produce fine droplets called atomized fluid. During the fluid atomization process, droplet size and distribution can be precisely controlled so that the droplets become very small and high-level particle distribution is achieved which can be easily evaporated. This method is widely used in various industries, including food industry (for the production of driedpowder products) and coating industry. The key factor that affects droplet size is the frequency and amplitude of the ultrasonic vibrations and the properties of the fluid, including the fluid viscosity and surface tension.
Materials and Methods
Based on a review of literature, it is clear that the modeling of the ultrasonic method for spray dryers and the production of milk powder has not been done so far. In the present work, first, the research background is reviewed and then, using the relationships provided for the ultrasonic atomization of different fluids in the reviewed articles, the effect of ultrasonic vibrations on the atomization and evaporation of milk as a food and the powder production was studied using spray drying process. Then the effects of various oscillation parameters such as frequency, amplitude and also the temperature of the fluid, which affects its viscosity, density and surface tension, on the rate of atomization of the fluid was investigated. In the present work, we first examine the fluid whose range of properties is true in relations. One of the most widely used liquids in the food industry is milk. By examining the viscosity, surface tension and density of the milk and obtaining the dimensionless numbers We, In and Oh, it is determined that the provided relations can also be used for milk. After calculating the diameter of the evaporated particles of milk due to ultrasonic vibrations as well as the evaporation rate, the independent variables of the research can be changed. First, in the constant physical properties of a fluid, we change the frequency and amplitude of ultrasonic oscillations and studied their effect on the produced particle diameter and evaporation rate. In the next step, with the constant frequency and amplitude of ultrasonic oscillations, the effect of changes in fluid properties (temperature change) on the produced particle diameter and evaporation rate was investigated. In the next stepthe effect of frequency and amplitude of ultrasonic fluctuations as well as changes in fluid properties (temperature change) on the powder diameter produced and the time required for the drying process was investigated. The analysis of all data obtained from the above steps was performed using Mathlab software.
Results and Discussion
The main and summary results obtained from the present study are as follows:
As the amplitude of the vibrations and the temperature of the milk increased, the drying time required for the evaporation of droplets decreased, but the powder diameter and the evaporation rate increased.
As the frequency of vibrations increased, the drying time required for the evaporation of droplets increased, but the powder diameter and the evaporation rate decreased.
The results showed that quadrupling the amplitude of the vibrations reduces the time required for the droplets to dry by 14.4% and increases the evaporation rate by 62.6%. At a constant temperature of the gas dryer and the milk, changing the frequency from 10 to 40 kHz results in 21.4% increase in the time required for the droplets to dry. Also, with increasing the temperature of the milk from 15 to 30°C, at a constant frequency and amplitude of vibrations, the time required for drying the droplets decreases by 12.4% and the diameter of the particles produced increases by 11.3%.
Conclusion
In this research, the process of ultrasonic assisted evaporation of whole milk and drying and production of milk powder has been modeled mathematically and thermodynamically. The calculation code was written using Mathlab software and after making sure that the solution conditions are in the desired range of equations, the results were presented. In the present work, the effect of the frequency and amplitude of ultrasonic vibrations as well as the initial temperature of milk on the diameter of the evaporated particles, the evaporation rate, the diameter of the powder produced and the time required for the evaporated droplets to dry by ultrasonic method was investigated.
Food Engineering
Behnaz Vafania; Milad Fathi; Sabiheh Soleimanian Zad
Abstract
The aim of this research was to investigate the efficiency of nozzle-less electrospinning for encapsulation of ajwain essential oil (as a hydrophobic bioactive) using two hydrocolloids (chitosan/gelatin) in order to enhance its antioxidant properties and stability for food applications. Nanofibers were ...
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The aim of this research was to investigate the efficiency of nozzle-less electrospinning for encapsulation of ajwain essential oil (as a hydrophobic bioactive) using two hydrocolloids (chitosan/gelatin) in order to enhance its antioxidant properties and stability for food applications. Nanofibers were spun using chitosan/gelatin in ratios of 1:6, 1:8 and 1:10 and ajwain concentrations of 20 and 40%. Solution properties (i.e. viscosity and electrical conductivity) were measured. Encapsulation efficiency and loading capacity data illustrated an enhancement with increasing of essential oil concentration. Fibers diameter and morphology were studied by scanning electron microscopy (SEM). The chitosan/gelatin nanofibers with ratio of 1:6 containing 40% essential oil had the highest encapsulation efficiency (99.9%), loading capacity (39.9%) and the smallest diameter (146 nm). Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) proved that during electrospinning, no any chemical interaction was occurred between ingredients and differential scanning calorimetry (DSC) data showed that essential oil was well encapsulated in nanofibers. Antioxidant properties were analyzed by 2,2-diphenyl-1-picrylhydrazylradical and approved the efficiency of encapsulation for protection of antioxidants.
Food Engineering
Sanaz Golmohammadzadeh; Farid Amidi-Fazli
Abstract
[1]Introduction: The biodegradability of synthetic plastics derived from petroleum is a very slow process and complete decomposition of them lasts several years. This increases environmental pollution. Extensive efforts have been made to develop and improve biopolymers-based packaging. Biopolymers derived ...
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[1]Introduction: The biodegradability of synthetic plastics derived from petroleum is a very slow process and complete decomposition of them lasts several years. This increases environmental pollution. Extensive efforts have been made to develop and improve biopolymers-based packaging. Biopolymers derived from renewable agricultural resources are an appropriate alternative to synthetic plastics. The use of nanotechnology in the field of polymer science has led to the production of nanocomposite polymers. The valuable nanocomposites would be produced if natural nanoparticles are used in composites preparation. Because of the importance of nanocomposites in the production of biodegradable films and due to desired properties of gelatin and carboxymethyl cellulose in film production, this study aimed to investigate the effect of glycerol and nanocellulose on the properties of gelatin-carboxymethyl cellulose nanocomposites. Materials and Methods: To prepare 12 different treatments based on statistical design, 1 g of gelatin and 1 g of carboxymethylcellulose were dissolved in distilled water to form a uniform solution. Then, glycerol as a plasticizer was added to the prepared solutions at different levels (20 to 60% w/w). The determined amount of nanocellulose (0- 30% w/w), based on the biopolymers weight, was added to the cooled blend at 70°C. Nanocellulose was extracted from cotton through the chemical method, cotton was gone under chemical hydrolysis by the sulfuric acid solution (65% w/v). The properties of gelatin-carboxymethylcellulose nanocomposites were studied. The produced nanocellulos evaluated by scanning electron microscopy and X-ray diffraction techniques. The thickness of the films was measured using a caliper with a precision of 0.01. At five different parts of each film. Water vapor flux and water vapor permeability through the film samples were determined. The dry matter of 20× 20 mm film samples before and after immersion in 50 ml of distilled water for 24h at 25 °C was determined to calculate the solubility in water of the films. To measure the moisture absorption of the nanocomposite samples, 20× 20 mm film pieces were kept in a container containing potassium sulfate saturated solution (RH= 97%) at 25°C for 4 days. Films were weighted initially and at the end of the experiment. Sessile drop method, a common technique for determining the wetting properties of solid surfaces, was then used to determine the contact angle. Ultimate tensile strength and elongation at break were measured. The belt-shaped sample (8× 1 cm) of the film was stretched by the instrument at a velocity of 1 mm/s. The color and transparency of the samples were evaluated in the black box by image processing technique. Total color difference (ΔE), yellow index (YI), and white index (WI) of the samples were calculated. Treatments were prepared according to central composite design (CCD) and were statically analyzed by response surface method (RSM). Results and Discussion: The prepared films showed low water vapor permeability (3.62× 10-11 to 2.23× 10-12 gm/m2Pas). The lowest amount of water vapor permeability was obtained when the low level of nanocrystalline cellulose (4.4%) was used. The high amounts of glycerol and nanocellulose increased the solubility of the films and even in some treatments the samples were completely dissolved in water. The hydrophilic nature of the gelatin and carboxymethyl cellulose used in the preparation of composites may be the reason for the high solubility of the produced films. At the same time, the samples showed high moisture absorption. Moisture absorption decreased as a result of the glycerol content increased, also the effects of the presence of nanocrystalline cellulose as a filler on the moisture absorption decrease cannot be neglected. A moderate contact angle of about 60º was observed, the interactions between the polar and the hydroxyl groups of the biomaterials used in the production of composites caused different behaviors observed in the various treatments. The interaction of nanocellulose and glycerol had a significant effect on the contact angle. The films had high ultimate tensile strength (84.37 MPa) while the elongation at break was 4.14% for the same treatment, which indicates low flexibility of the produced films. The color of the samples was evaluated as suitable. The use of 60% glycerol and 4.4% nanocellulose results in the production of films with desirable properties. The use of gelatin and carboxymethylcellulose produced composites that had improved properties in the terms of water vapor permeability and surface wetting compared to pure films.Composites made of gelatin and carboxymethylcellulose showed high ultimate tensile strength, although the elongation at break of them was not desirable. In terms of barrier properties against the water vapor, prepared composites demonstrated improved properties when compared to other bio-based made films. On the other hand, in terms of hydrophilicity, they are classified as moisture-sensitive films, which limits their use for foods with high moisture content. The use of carboxymethyl cellulose can improve the water vapor permeability of pure gelatin films. Also, the use of gelatin increases the contact angle of water of pure carboxymethyl cellulose films. Gelatin-carboxymethyl cellulose nanocomposite contains 60% glycerol and 4.4% nanocellulose presents improved and desirable properties.
Food Engineering
Sajad Jafarzadeh; Mohsen Azadbakht; Faryal Varasteh; Mohammad Vahedi Torshizi
Abstract
Nowadays, the quality of processed fruits or products is defined by a set of physical and chemical properties. In this study, due to the sensitivity of persimmon fruit to pressure, the parameters affecting the color changes of this fruit after pressure have been investigated. Three different coatings ...
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Nowadays, the quality of processed fruits or products is defined by a set of physical and chemical properties. In this study, due to the sensitivity of persimmon fruit to pressure, the parameters affecting the color changes of this fruit after pressure have been investigated. Three different coatings and packing materials and two loading were applied to study the color changes of the samples. Samples were stored in the refrigerator for 25 days. According to the results obtained for the value of L*, b*, Chroma index, Hue index and color changes, the use of 1 mM polyamine coating had a significant effect and caused less change than other coatings. Foil container packaging with polyolefin film has also been better packaged. The lowest percentage reduction for L*, a*, b* , Chroma index and Hue index values was obtained in the 1 mM polyamine with a value of 8.26%, -26.43%, 12.35%, 1.31% and 120.995% respectively, Also the highest value was obtained in the uncoated state with a value of 18.49%, 73.32%, 19.84%, 15.95%, 152.36%. Finally, polyamine coating treatment has a positive effect to prevent the percentage reduction of color parameters of samples. The best coating treatment was polyamine with a concentration of 1 mM
Food Engineering
Maryam Azizkhani; Rafat Karbakhsh Ravari
Abstract
The objective of this study was to improve the survival of lactic acid bacteria (LAB) in Tarhana soup as a non-dairy matrix. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles were encapsulated in electrospun nanofiber mats fabricated from corn starch (CS) and sodium alginate ...
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The objective of this study was to improve the survival of lactic acid bacteria (LAB) in Tarhana soup as a non-dairy matrix. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles were encapsulated in electrospun nanofiber mats fabricated from corn starch (CS) and sodium alginate (SA) and the protective effect of the nanofibers were investigated on the cells during the preparation of Tarhana and in the gastrointestinal tract. The moisture content of the control and nanofiber- loaded dried Tarhana samples was 8.75 and 8.71%, respectively; therefore, using nanofiber mats in the formulation had no significant effect
on the moisture content of the samples. A negative zeta potential value of -15.1 mV was found for LAB- loaded nanofibers. The nanofibers mats prepared from SA and CS mix showed a bead- free and clean structure with uniformity in size. The diameter size of most of the fibers ranged from 175- 338 with an average of 265 nm. Loading nanofiber mats with L. delbrueckii subsp. bulgaricus and S. thermophilus cells led to a uniform distributed beaded structure and the average diameter enhanced to approximately 763 nm. The viability of L. delbrueckii and S. thermophilus at the end of the electrospinning process was 92.82% and 95.83%, respectively, which indicating a slight loss in their population. Survival of nanoencapsulated S. thermophilus and L. delbrueckii was 93.50% and 89.16% respectively, while for free cells it was 85.3 and 76.4% that showed considerable protective effect of CS/SA fibers on the cells against dehydration of Tarhana medium. Nanofiber mats improved the stability of the cells against ordinary heat treatment used in preparing Tarhana soup. The survival rate of S. thermophilus was higher than L. delbrueckii subsp. bulgaricus and a significant difference was observed between the viability of free and nanoencapsulated bacteria. The survival of CS/SA nanoencapsulated S. thermophilus and L. delbrueckii subsp. bulgaricus was 83.25% and 80.21%, respectively, which is indicative of the significant protective effect of fibers on the cells against the heating process. The nanofibers also provided good stability for the cells in the gastrointestinal tract as 106 to 107 CFUg-1 of the cells were survived which is within the recommended level of potential probiotic dose to be effective. There was no significant difference in the color of all samples. Nanoencapsulation in CS/ SA nanofiber mats improved the protection of both LAB strains in simulated fluids of the stomach and intestine (Table 4). After continuous exposure to simulated gastrointestinal fluid, a significant loss of viable free LAB cells (higher than 4 log CFU/ml) was found while the population of S. thermophilus and L. delbrueckii subsp. bulgaricus encapsulated in CS/ SA nanofibers decreased only 0.45 and 0.37 log CFU after 120 min (p> 0.01), 0.93 and 0.80 log CFU after 180 min (p< 0.01), respectively. Tarhana soup prepared with probiotic– loaded nanofibers gained higher scores in terms of consistency, mouth feel, odor, taste, flavor, and overall acceptability attributes. Tarhana soup with nanofibers possessed much sour taste and flavor than samples prepared with free cells of probiotics. The results of the present study indicated that the protection obtained from CS/ SA capsules secured around106 to 107 CFU/g of the probiotic cells which are within the recommended level of probiotic dose to be functional in consumers’ body. Therefore, this product can be used by the consumers like vegetarians and lactose or milk peptide intolerants who do not consume dairy products but need potential fermented probiotic food.
Food Engineering
Samaneh Monajem; Ali Ganjloo; Mandana Bimakr
Abstract
Conclusion: Based on the findings of the current study, the 75% v/v A. vera gel coating could be a promising natural coating agent for preservation of bioactive compounds of cherry tomatoes during the postharvest life especially at storage temperature of 5 ºC.
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Conclusion: Based on the findings of the current study, the 75% v/v A. vera gel coating could be a promising natural coating agent for preservation of bioactive compounds of cherry tomatoes during the postharvest life especially at storage temperature of 5 ºC.
Food Engineering
Mohsen Zandi; Ali Ganjloo; Mandana Bimakr; Abolfazl Gharebaghi
Abstract
Introduction: Grape is a non-climacteric fruit with a low rate of physiological activity but is subject to serious physiological and parasitic disorders after harvest and during long term storage (Ciccarese et al., 2013). Currently, Edible coatings have been studied as potential substitutes for conventional ...
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Introduction: Grape is a non-climacteric fruit with a low rate of physiological activity but is subject to serious physiological and parasitic disorders after harvest and during long term storage (Ciccarese et al., 2013). Currently, Edible coatings have been studied as potential substitutes for conventional plastics in food packaging. Edible coating is a thin layer of edible material formed as a coating on a food product. Edible coating can offer several advantages to the fresh fruit and vegetable industry such as improvement in the retention of color, acids, sugar and flavor components, the maintenance of quality during shipping and storage, the reduction of storage disorders and improved consumer appeal (Antoniou et al., 2015; Cazon et al., 2017; Fakhouri et al., 2015; Galus & Kadzińska, 2015). Farsi gum as a novel source of polysaccharides has drawn much attention in a wide range of various fields such as pharmaceutics, food and cosmetics industries. Functional properties of Farsi gum are influenced by its structure and molecular weight (Hadian et al., 2016; Joukar et al., 2017). By inclusion of bioactive compounds in the Farsi gum network the aforementioned impairments could be overcome and moreover, new protective and functional valences could be added. The inclusion of lipid-based component in Farsi gum gives it excellent light and moisture barrier properties. The benefic impact on human health of hemp seed oil is worldwide recognized. A recent study demonstrated the antimicrobial properties of hemp seed oil. Due to their abundance in biologically active compounds, hemp seed oil is promising natural alternatives that may extend the shelf-life, microbiological safety and nutritional values of food (Cozmuta et al., 2015; Leizer et al., 2000; Salarnia et al., 2018). Growing awareness of the quality of fruit has necessitated increasing effort to develop rapid and non-destructive methods for evaluating fruit quality (Bhargava & Bansal, 2020; Rachmawati et al., 2017; Tao & Zhou, 2017; Wu & Sun, 2013). The aim of this study was the consideration of image processing application for grape sorting based on visual surface characterize. Materials and Methods: Coating emulsion was prepared using (Farsi gum (0%, 1.5% and 3%), hemp seed oil (0%, 0.075% and 0.15%) and glyceride (0.3%)). grape fruit were coated by immersion in coating dispersion for 5 min. Samples were then allowed to loss the excess coating dispersion. Coatings were developed at room temperature during an hour. Samples were refrigerated at 4± 1°C for 28 days and analyses were performed at days 0 and 28. Defect identification and maturity detection of grape fruits are challenging task for the computer vision to achieve near human levels of recognition. The image acquisition was performed in a homogenously controlled lighting condition. Considering the camera lens’s focal length, the samples were placed 25 cm under the camera’s lens to be under camera’s field of view. The images of grape were segmented from the background using thresholding of the high contrast images via MATLAB software (R2019a, image processing toolbox). The optimum threshold value was obtained to be 0.35, 0.45 and 0.30 for R, G and B channel, respectively. Results and Discussion: The proposed techniques can separate between the defected and the healthy grape fruits, and then detect and classify the actual defected area. Classification is performed in two manners which in the first one, an input grape is classified with two different algorithms (RGB and binary). The Result showed that the accuracies for detecting the surface defects on grape were 97.73% and 96.30% using RGB and binary algorithms, respectively. Proposed method can be used to detect the visible defects of coated grape, and to grade the grape in high speed and precision. Conclusions: The results of this research and similar ones can provide helpful recommendations in grading fruits for fresh consumption. The simplicity and the efficiency of the proposed techniques make them appropriate for designing a low-cost hardware kit that can be used for real applications.
Food Engineering
Morteza Kashaninejad; Seyed Mohammad Ali Razavi; Mohammad Reza Salahi
Abstract
Introduction: One of the products that its production has not been investigated well and is an imported product is cream powder. Foam mat drying is a widespread technique to dehydrate liquid or semi-liquid foods with high viscosity, adhesion and high sugar content, which are usually difficult to dry. ...
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Introduction: One of the products that its production has not been investigated well and is an imported product is cream powder. Foam mat drying is a widespread technique to dehydrate liquid or semi-liquid foods with high viscosity, adhesion and high sugar content, which are usually difficult to dry. Evaluating moisture content over time is the first indication of how the drying process is performed and can be used as a tool to compare the drying behavior of food. The rate of drying, which is expressed as a function of time or moisture content, is also a very important parameter that helps to understand drying properties of a material. Color can also indicate chemical changes in food during the thermal process such as browning and caramelization. Therefore, since in the drying industry, process time, product quality, optimization and equipment design are directly affected by the rate of drying of food, hence, in this study, in the process of drying the camel milk cream by the foam mat drying method, drying operation at temperatures of 45, 60 ,and 75 °C and thicknesses of 1, 3 and 5 mm was performed in a non-continuous cabinet dryer to evaluate the kinetics of drying , structure and color of the dried foam. Materials and Methods: Camel milk cream was mixed with carboxymethyl cellulose (0.1%), cress seed gum (0.1%) and 80% whey protein concentrate (5%) at 25 ° C. After pasteurization, the samples were stirred with a mixer at a maximum speed of 1500 rpm (5 minutes) for proper aeration. The foam samples were poured into a plate in a thin layer with thicknesses of 1, 3 and 5 mm and then dried in a dryer at temperatures of 45, 60 and 75 ° C until a constant moisture was reached. The process treatments were performed in a completely randomized central composite design (CCD) (5 replications at the center point) for 2 variables at three levels. The effective diffusion coefficient was calculated based on the second Fick's law of diffusion. Then, using Arrhenius equation, which shows the relationship between temperature and effective diffusion coefficient, activation energy was also calculated. After the drying stage, in order to investigate the changes in moisture during the drying, by determining MR, we have used some experimental models that were previously used for drying agricultural products, to fit the experimental data using the statistical software MATLAB 2016. Results and Discussion: The results showed that increasing the temperature from 45 to 75° C reduced the drying time of the samples by almost 50%. Reducing the thickness from 3 to 1 mm led to an 80% reduction in drying time of the samples. The overall effective diffusion coefficient of the tested samples varied between 7.09×10-10 and 8.11× 10-9 m2/s. The increase in the temperature led to an increase in the effective diffusion coefficient of the samples. The activation energy of the samples varied between 25.59 and 38.22 kJ /mol, and comparison of the means showed that the activation energy of the samples was also increased by increasing the foam thickness. Totally, 17 models were evaluated to investigate the drying kinetics of the samlses and in all cases of foam drying , page and Midilli models with R2 values above than 0.99 and the lowest values of RMSE indicate the best fit with the experimental data among the 17 fitted model. Examining the digital images of the samples also showed that at low temperatures, the structure of the dried foams was smooth and it became more uneven and porous as a result of increasing the temperature. Also, the trend of changes in the parameters of the gray level co-occurrence matrix (GLCM) (energy, correlation, and homogeneity) of the samples was almost the same with the changes in temperature and thickness so that, the increase in the drying temperature and a decrease in the thickness of the samples led to a decrease in these parameters. Increasing the foam thickness at high temperatures led to a decrease in the browning index and at low temperatures, led to an increase in the browning index of the samples.
Food Engineering
Ali Saeidan; Mehdi Khojastehpour; Mahmood Reza Golzarian; Marzieh Moeenfard
Abstract
Introduction: Due to the fact that the presence of high doses of aflatoxin in agricultural products such as cocoa beans is unacceptable in terms of national and international standards, appropriate quality control tests should prevent such products to entering in the process of processing cocoa beans. ...
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Introduction: Due to the fact that the presence of high doses of aflatoxin in agricultural products such as cocoa beans is unacceptable in terms of national and international standards, appropriate quality control tests should prevent such products to entering in the process of processing cocoa beans. Conventional methods of detecting aflatoxins such as ELISA and HPLC are very time consuming, expensive and require expertise, so replacing these tests with non-destructive and rapid methods such as near-infrared spectroscopy can increase the detection efficiency. Brado et al. (Berardo et al., 2005) used infrared spectroscopy to evaluate and diagnose Fusarium verticillium, which produces fumonicin toxin in maize. Manvar et al. (Mohammadi Manvar, 2015) used transmission and reflection Infrared spectroscopy to detect aflatoxin levels in Iranian pistachios. Singh et al. (2012) used hyperspectral imaging in the range of 700-1100 nm to detect fungal contamination of Penicillium SPP, Aspergillus Glaucus, and Aspergillus Niger in wheat. Kandpal et al. (Kandpal et al., 2015) in a research work using hyperspectral imaging in the range of 700-1100nm classified grains of maize contaminated with aflatoxin toxin using PLS-DA into five groups. In current study, an attempt was made to detect the amount of aflatoxin in cocoa beans using infrared spectroscopy and to classify healthy and infected beans into groups. Materials and Methods: In this research, 180 cocoa beans, each weighing 1 gram, were selected to do analyses. One mg of aflatoxin B1 powder (A. flavus, A 6636, Sigma-Aldrich, St. Louis, Mo USA) was prepared from Sigma Aldrich representative in Iran and by dissolving this powder in absolute ethanol and concentrations of 20µg/kg, 500µg/kg was obtained as mentioned. For cocoa bean spectroscopy, a near infrared spectrometer in Shiraz University Central Laboratory (NIRS XDS Rapid Content Analysis) was used, which has the ability to spectroscopy in the range of 400-2500 nm. PLS-DA method was used to classify aflatoxin-infected samples from healthy samples. All 180 experimental samples were divided into two groups of training (120 samples) and test (60 samples) and the constructed model was first calibrated with training values and then evaluated with test data. Due to the fact that some noise is always stored in the spectral data and in order to remove this noise, a series of mathematical pretreatment, including: first and second derivatives was used (Chen et al., 2013; Nicolai et al., 2007). Results and Discussion: Comparing the average amount of infrared reflection spectrum, it is revealed that healthy grains have less reflection intensity than infected grains. Also, there are a number of local maximums and minimums where the difference in reflective intensity is more pronounced than elsewhere, and this phenomenon is due to the different concentrations of toxins in cocoa beans. After applying the second Savitzie Golay derivative pretreatment and performing PLS-DA classification using two latent variables, the distinction between classes can be clearly seen. The separation rate of the samples on the second LV is more specific, however, the second and first class samples in this LV have a closer score to each other. The peaks observed at 1440 nm and 1482 nm according to the first Everton O-H bond can be related to fungal contamination (Berardo et al., 2005; Sirisomboon et al., 2013). Also, the peak at 1838 nm is related to the tensile C-H bond, which can be related to the CH2 groups. According to the results obtained from the calibration, cross-validation and testing sections, it is determined that the degree of calibration error (ER) and the degree of error-free calibration (NER) in the pretreatment mode with the second-order derivative of Savitz Golay are the lowest and highest values, respectively. Also, in this pretreatment for the calibration model and testing, the specificity index for the first-, second- and third-class samples are equal to 1.00, which means that all classes are correctly classified. In the cross-validation model, the value of the specificity index for the third class (samples with 500 ppb contamination) is equal to 97%. This indicates that 97% of infected seeds are correctly classified in the third group and only 3% in the other groups are incorrectly classified. Conclusion: The present study demonstrates the feasibility of near-infrared spectroscopy to identify and classify cocoa beans contaminated with aflatoxin. The results showed that the coefficients of independent variables (spectral wavelengths including 1440, 1482 and 1838 nm) decreased according to increasing in the concentration of toxin. Finally, it can be said that the method of detecting aflatoxin contamination using infrared spectroscopy is an efficient, non-destructive and fast method.
Food Engineering
Mohsen Azadbakht; Bahareh Eshaghi; Ali Motevali; Azim Ghasemnezhad
Abstract
In this study, temperatures (40, 50, and 60°C), air velocity (3, 5, and 7 m/s) and pre-treatment (without pre-treatment, blanching, and microwave) were used as variables for investigation of antioxidant activity of dried artichoke leaves. The results revealed that variations in temperature and air ...
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In this study, temperatures (40, 50, and 60°C), air velocity (3, 5, and 7 m/s) and pre-treatment (without pre-treatment, blanching, and microwave) were used as variables for investigation of antioxidant activity of dried artichoke leaves. The results revealed that variations in temperature and air velocity of the drying chamber and different pre-treatments significantly affected the free radical scavenging level and total phenol content in this plant. Based on the results obtained, it can be concluded that by increasing the temperature and air velocity and using blanching and microwave pre-treatments, the free radical scavenging level and total phenol content increased. The maximum percentage of free radical scavenging was 72.08% at 60°C and an air velocity of 7 m/s in the drying state by using microwave pre-treatment. The maximum total phenol content was 3.55 mg/g of dry matter at 60°C and an air velocity of 7 m/s in the drying state by using microwave pre-treatment.
Food Engineering
Behdad Shadidi; Reza Amiri Chayjan
Abstract
The drying of food can extend the shelf life of food, reduce transportation and storage costs. Fick's second law is commonly used to evaluate the mass data in the drying process in a standard way and is based on many assumptions. Understanding the meaning of mass transfer in products can improve the ...
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The drying of food can extend the shelf life of food, reduce transportation and storage costs. Fick's second law is commonly used to evaluate the mass data in the drying process in a standard way and is based on many assumptions. Understanding the meaning of mass transfer in products can improve the drying process and product quality. Computational fluid dynamics (cfd) models fluid flow situations utilizing powerful computer and applied mathematics in order to predict mass transfer in industrial processes. The aim of this research was numerical study of the drying behavior of pistachio nut using CFD method and evaluating the numerical results in the bed condition of fluid, semi fluid and fix bed as well as air temperatures of 90, 75, 60 and 45°C. During drying using computational fluid dynamic and the Fluent CFD code, the external flow and temperature fields around the cylindrical object (7.5× 10 millimeter) will be predicted in the numerical analysis. A laboratory fluid bed dryer was used for drying experiments. The main parts of the dryer are forward radial fan, drying chamber, electrical heater, inverter, temperature controller. The dryer attachment tools are input and output temperature sensors, anemometer and computer. The numerical part was verified and juxtaposed with the experimental data. The numerical solution result at 60, 75 and 90°C were so close to experimental results except for air temperature of 45°C. Mean absolute error in fix bed, at 60, 75 and 90°C were 0.2123, 0.1257 and 0.0337 which were lower than 45°C temperature and R2 values for these temperatures were 0.9903, 0.9705 and 0.9807, respectively. As the temperature decreased, the values of Eabs and X2 increased in all bed conditions. The average value of R2 for all applied bed conditions was 0.9850. This value showed high correlation between experimental and numerical results.
Food Engineering
Aliakbar Gholamhosseinpour; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi
Abstract
UF- Feta cheese is mostly produced from bovine milk and is usually consumed fresh or only after a short period of ripening (60 days). In this research, the influence of commercial starter cultures (SafeIT 2, FRC- 65 and R- 704) and ripening time (0- 60 days) on chemical (total solids, fat, protein, ash, ...
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UF- Feta cheese is mostly produced from bovine milk and is usually consumed fresh or only after a short period of ripening (60 days). In this research, the influence of commercial starter cultures (SafeIT 2, FRC- 65 and R- 704) and ripening time (0- 60 days) on chemical (total solids, fat, protein, ash, salt, acidity, pH), biochemical (pH 4.6, TCA, PTA-soluble nitrogen, acid degree value) and sensory (color and appearance, aroma, texture, flavor and total acceptance) characteristics of UF- Feta cheese analogues was investigated. According to our results, the starter culture types were known to have a significant effect (P≤ 0.05) on pH, %salt, %protein, and pH 4.6- soluble nitrogen of cheeses, whereas the other chemical properties were not affected by them. Ripening time only significantly (P≤ 0.05) influenced %acidity, pH, %salt, acid degree value (meq acid 100 g-1 fat), %protein and %proteolysis products of samples. Also, the starter culture and ripening time did not affect the sensory properties significantly, excluding color and appearance, however, the produced cheeses from SafeIT 2 had higher sensory scores compared with the others containing FRC- 65 and R- 704 cultures.
Food Engineering
Hadi Samimi Akhijahani
Abstract
Introduction: Drying of agricultural products is one of the main ways to prevent product spoilage. There are several methods to dry agricultural products, including direct sunlight, hot, sunny weather, microwave, vacuum, and freezer which use different energy sources. Due to constrain of fossil ...
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Introduction: Drying of agricultural products is one of the main ways to prevent product spoilage. There are several methods to dry agricultural products, including direct sunlight, hot, sunny weather, microwave, vacuum, and freezer which use different energy sources. Due to constrain of fossil fuels supply, the price of this type of energy is increasing thus the tendency to use renewable energies is increasing (Purohit and Kandapal, 2005; Purohit et al., 2006). In Iran the drying efficiency of solar dryers is low because less solar energy is converted into thermal energy. Therefore, many measures have been taken to increase the efficiency of solar collectors which causes to obtain the dried samples with better quality and lower cost. In this study a combination of tracking system and phase change materials (PCM) are used to increase the efficiency of solar dryer cabinet with three types of collectors including flat plat (FPC), parabolic trough (PTSC) and evacuated tube (ETSC) collectors. Materials and Methods: The dryers used in this study include a cabinet connected to a flat plat, parabolic trough and evacuated tube collectors. In all of the dryers, PCM have been used to maximize solar energy utilization. Moreover to get the maximum solar radiation the tracking system used in FPC and PTSC and a storage tank with fluid pump used in PTSC and ETSC. The air flow rate inside the system was about 0.018 kg.s-1 for all the experiments. The experiments were performed in three continues days from 16 to 18 June 2018, from 8:00 to 24:00. Tomato sample with a thickness of 9 mm was considered for drying process. To describe the drying process of the samples, the moisture ratio versus time was considered. Also, the drying efficiency was defined considering the ratio of energy (thermal and mechanical) consumed to heat the product and extract moisture from the product (Qm) to the total energy used for drying process, including fluid thermal energy (Qf) and mechanical energy (Emec) (Fudholi et al., 2014). In order to evaluate the quality of the dried product at different modes, three quality parameters including color difference, shrinkage and rehydration ratio were considered. Color difference between the fresh and dried samples was evaluated as one of the most important factors that the customer was considered for selection (Magdic et al., 2009). The change in the volume of the dried product compared to the fresh product is defined as shrinkage. Moreover, to evaluate the rehydration ratio the weight of water absorbed by the samples was considered. Results and Discussion: The effect of variations of the intensity of solar radiation on the amount of solar energy taken by the collectors was negligible. The time required to dry tomato slices by the dryer equipped with FPC was longer than the other systems. The results also showed that the highest drying efficiency is related to the dryer with ETSC and it was about 39.02%. The least value is related to the dryer with FPC and it was about 30.12%. Due to the long drying time the use of the fan and the pump increase and the amount of energy consumed to drying the product increases as well. Thus the efficiency of the dryer with FPC decreases. The values of specific energy for the dryer with FPC, PTSC and ETSC were obtained as 7.12, 7.92 and 8.34 MJ/kg, respectively. The results of qualitative evaluation of dried tomato slices showed that the product obtained from the dryer equipped with ETSC, due to the short drying time, the color changes and the shrinkage was suitable in comparison with the other reports. The amount of rehydration ration was the highest as well. Using PCM had no adverse effect on the quality of the dried samples. The results showed that the dryer with ETSC had higher efficiency (about 39.02%) and the quality of the samples was suitable compared to other systems. Using recycling system can improve the thermal efficiency of the solar dryer.
