Food Chemistry
Negar Soleimanpoor Tamam; Akram Arianfar; Vahid Hakimzadeh; Bahareh Emadzadeh
Abstract
Introduction Gelatin is one of the most widely used colloidal proteins, which has unique hydrocolloidal property. Gelatin is derived from collagen by changing the thermal nature. This product is widely used in food, pharmaceutical, biomedical, cosmetic and photography industries. Global gelatin ...
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Introduction Gelatin is one of the most widely used colloidal proteins, which has unique hydrocolloidal property. Gelatin is derived from collagen by changing the thermal nature. This product is widely used in food, pharmaceutical, biomedical, cosmetic and photography industries. Global gelatin demand for food and non-food products is increasing. Two important properties of nanoparticles are: Increasing the surface-to-volume ratio of nanoparticles causes the atoms on the surface to have a much greater effect on their properties than the atoms within the particle volume. The effects of quantum size, which is the second feature. Methods for preparing nanoparticles from natural macromolecules: In general, two major methods for making protein nanoparticles have been reported Emulsion-solvent evaporation method and sedimentation or phase separation method in aqueous medium. Numerous methods have been reported for the preparation of nanoparticles from natural macromolecules. The first method is based on emulsification and the second method is based on phase separation in aqueous medium. In the first method, due to the instability of the emulsion, it is not possible to prepare nanoparticles smaller than 500 nm with a narrow particle size distribution. Therefore, coagulation method or anti-solvent method which is based on phase separation was proposed to prepare nanoparticles from natural macromolecules. Materials and Methods Type B (cow) gelatin was purchased from processing company with Bloom 260-240 food and pharmaceutical Iran solvent gelatin solution of 25% aqueous acetate glutaraldehyde from Iran Neutron Company. Two-stage anti-solvent method was used to produce gelatin nanoparticles. Then, to form nanoparticles, acetone was added dropwise while stirring until the dissolved acetone begins to change color and eventually turns white, which indicates the formation of nanoparticles. Finally, glutaraldehyde solution was added for cross-linking and finally centrifuged. Results and Discussion The results showed that with increasing gelatin concentration, nanoparticle size and PDI increased significantly. According to the announced results, the solvent has a direct effect on the size. Therefore, the best mixing speed is determined to achieve the smallest particle size. Zeta potential is the best indicator for determining the electrical status of the particle surface and a factor for the stability of the potential of the colloidal system because it indicates the amount of charge accumulation in the immobile layer and the intensity of adsorption of opposite ions on the particle surface. If all the particles in the suspension are negatively or positively charged, the particles tend to repel each other and do not tend to accumulate. The tendency of co-particles to repel each other is directly related to the zeta potential. Fabricated gelatin nanoparticles have a stable structure, and are heat resistant. These nanoparticles are ready to be used to accept a variety of aromatic substances, compounds with high antioxidant properties, a variety of vitamins and heat-sensitive substances. ConclusionThe results of this study showed that the optimal conditions for the production of a particle of 88.6 nm at 40 ° C, the volume of acetone consumption was 15 ml, concentration 200 mg and speed 1000 rpm, and the morphology of gelatin nanoparticles have resistant, spherical polymer structure and mesh with a smooth surface that can be clearly seen under an electron microscope.
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 Technology
Mohammad Sadegh Arab; Hannan Lashkari; Mehrdad Niakosari; Mohammad Hadi Eskandari
Abstract
This study aimed to evaluate the effects of intelligent pH-sensitive composite film based on gelatin and Persian gum incorporated with purple carrot extract (PCE) on the freshness of wrapped mozzarella cheese. In this regard, the color, pH, yeast and mold count of control and treatments wrapped with ...
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This study aimed to evaluate the effects of intelligent pH-sensitive composite film based on gelatin and Persian gum incorporated with purple carrot extract (PCE) on the freshness of wrapped mozzarella cheese. In this regard, the color, pH, yeast and mold count of control and treatments wrapped with intelligent pH-sensitive composite film during 60 days were evaluated. The results showed that the pH significantly reduced in wrapped cheese with and without PCE (control) samples during storage. However, this reduction was more pronounced in the control sample (P<0.05). Additionally, the application of composite film on cheese affected the color during storage. It was observed that L* and a* values of the composite film-wrapped cheese were significantly higher than the control sample, but the b* values were significantly lower than the control sample. Moreover, poor microbial growth (yeasts and mold) was observed in cheese samples wrapped by composite film with purple carrot compared to the control. Also, the pH of the composite film with extract significantly decreased from 6.33 to 4.85 during storage (P < 0.05), which showed the changes of color from purple to pink. After 40 days, the color changed to pink, indicating the end of the cheese storage. Therefore, it was concluded that the pH-sensitive film, while being an effective method to improve the shelf life of mozzarella cheese, can also use as an indicator for freshness.
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 Technology
Elham Mobini; Leila Nateghi; Mohammad Reza Eshaghi
Abstract
Materials and Methods: To compare physicochemical (pH, humidity, brix and water activity), texture properties (adhesiveness, cohesiveness, springiness, gumminess, chewiness, hardness and deformation of hardness), color indices (L*, a* and b*) and sensory (taste, odor, color, texture and overall acceptance) ...
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Materials and Methods: To compare physicochemical (pH, humidity, brix and water activity), texture properties (adhesiveness, cohesiveness, springiness, gumminess, chewiness, hardness and deformation of hardness), color indices (L*, a* and b*) and sensory (taste, odor, color, texture and overall acceptance) properties of pastille obtained from fish gelatin. The experiments were performed in a completely randomized design. In this study, 5 treatments with three repetitions were examined. In order to compare the means, Duncan's one-way analysis of variance was used at the 95% confidence level using Minitab software version 16. Results and Discussion: According to the results of gel formation temperature, gel melting temperature and gel melting time of fish gelatin were lower than commercial gelatin but gel formation time in fish gelatin was higher than commercial gelatin. Also, the extraction efficiency of gelatin from Kilka fish was 9.204%. Effect of different percentages of extracted fish gelatin on pH, moisture, brix, water activity, color indices (L*, a* and b*), texture properties (adhesiveness, cohesiveness, springiness and gumminess) and sensory evaluation (taste, odor, color, texture and overall acceptance) was significant (p>0.05). The results showed that by increasing the replacement of different percentages of fish gelatin, pH, Brix, L*, all textural histological and sensory evaluation factors decreased and moisture content, water activity and colors a* and b* increased. Differences in pH of gelatins may be due to the type and strength of acid used during the extraction process. Also, due to the replacement of fish with skin and bones in acid and due to having more minerals in the bones than fish meat, more acidic treatment is needed. Therefore, the difference in pH of fish gelatin and cow gelatin can be different depending on the extraction conditions and the type of fish. Hydrochlorothiazine gelatin is a protein that, at temperatures above 35 to 45 degrees Celsius, has a complex structure that dissolves in water and increases brix. The results showed that the amount of water activity of samples containing fish gelatin was higher than commercial gelatin, which could be due to the higher moisture content of gelatin extracted in fish and the extraction conditions and its use in the production of pastilles. The presence of Kilka fish gelatin in the pastel formulation caused the samples to get darken or turn red due to the increase in a * and b * indicators. The reason for the discoloration of the specimens can be due to the presence of carotenoids in the tissues of fish (tonagazantine (yellow), lutein (yellowish-green), beta-carotene (orange), duragazantine (yellow), zaxanthin (orange-yellow), Contagantine (red-orange), astaxanthin (red), and taragzantine (yellow)). The reason for the instability and poor rheological properties of fish gelatin compared to commercial gelatin is mainly related to the low number of proline-rich regions and low amounts of immunoassides (hydroxyproline and proline) in the collagen and gelatin molecules of fish compared to warm-blooded animals. The content of proline and hydroxyproline amino acids in fish gelatin is lower than in animal gelatin, such as pork, which exhibits better viscoelasticity. Therefore, they show weaker viscoelastic properties than commercial gelatin. In addition, fish gelatin contains less alanine, and this amino acid is commonly found in areas rich in proline and hydroxyproline. Most of these amino acids in commercial gelatin are one of the main reasons for their higher viscosity. The release of flavor is significantly related to the texture of the gel, and gelatin gels, due to the harder texture, release less flavor, which in turn reduces the overall acceptance score in samples containing high amounts of gelatin. Watman's filter paper, vacuum pump, ion exchange resin are commonly used to remove odors and derivatives, and vacuum evaporators are used to eliminate the unpleasant odor of fish in order to eliminate odors, dyes, unfavorable fish flavors, and unstressed collagen. However, the smell and taste of the remaining fish of the above methods reduce the sensory evaluation scores in treatments containing fish gelatin, and the main reason for the decrease in sensory evaluation scores in fish gelatins is the persistence of fish odor and taste in gelatin.T2 treatment (containing 50% fish gelatin + 50% commercial gelatin) was selected as superior treatment because of its proximity to control, physicochemical, rheological and sensory evaluation. In general, the results showed that using different percentages of gelatin extracted from Kilka fish had no adverse effect on the physicochemical and rheological properties of pastille and only sensory evaluation reduced due to the taste and odor of Kilka fish. The taste of pastilles produced covered the poor sensory evaluation properties of fish pastels produced from gelatin and used in industrial gelatin production.
Zahra Eskandari; Seyed Ali Jafarpour
Abstract
Introduction: Gelatin is a water-soluble protein mixture that is obtained by partial hydrolysis of collagen, which forms the major protein in bones, cartilage, and skin. Gelatin is made from collagen fibers, which is low in protein, cholesterol, fat and carbohydrates, with a special positive effect on ...
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Introduction: Gelatin is a water-soluble protein mixture that is obtained by partial hydrolysis of collagen, which forms the major protein in bones, cartilage, and skin. Gelatin is made from collagen fibers, which is low in protein, cholesterol, fat and carbohydrates, with a special positive effect on human health. Gelatin is one of the most notable natural biopolymers, the most important source of this hydrocolloid is pig. Trying to find suitable gelatin supplements for food products is increasing. Fish gelatin is one of the most suitable mammalian gelatinous substitutes and is accepted as a Halal (Kosher) food item. The purpose of this study was to extract gelatin from sturgeon Beluga skin using pepsin enzyme and then investigate the effect of the enzyme on the improvement of physiochemical and its functional properties in comparison to the gelatin extracted by chemical method. Material and Methods: Pre-treatment and extraction of gelatin and application of factorsSkin Preparation was performed according to Feng et al. (2013) with slight changes in pre-treatment steps. A solution of 3.5% NaCl was used to remove non-collagenic proteins and 0.5% sodium carbonate solution (Na2CO3) to remove lipid from the skin. The initial pretreatment was carried out with a solution of 3.5% sodium chloride at a rate of 1:10 w / v at a speed of 180 rpm for 6 hours which was replaced every 3 hours with the water. Extraction by was carried out following Tong et al. (2013) method. Gelatin was obtained from pre-treated skin in distilled water at temperature of 30, 40 and 50 degrees Celsius and a percentage of enzymes (0.01, 0.055 and 0.1) at different pH (2, 3 and 4) for 6 hours and 45 minutes in hot water bath. Then, the mixture was kept in the boiling water bath, for 5 minutes to inactivate the enzyme. The solution was passed through a cleaning cloth and then centrifuged at 3500 rpm for 20 min and finally was lyophilized in a freeze-drier. In this research, the Response surface methodology response (RSM) method was used to optimize the experimental treatments. The central composite rotatable design was used to optimize the gelatin enzyme extraction process. Results and Discussion: The α chains were clearly visible in the sample extracted by the enzyme, with molecular weight of 130 kDa (treatment 5), while the α2 chain is much weaker in the extracted gelatin by chemical method. By decreasing enzyme ratios, chains with molecular weights of less than 130 kDa disappeared gradually in chemical samples as well as in an enzyme-extracted sample (treatment 19). The gelatin extracted by the enzymatic method contains α1 and α2 chains. In the average amount of enzyme (treatment 17), the α2 chains were relatively weaker than the maximum value of the enzyme (treatment 5), and these chains almost disappeared in the minimum amount of enzyme (treatment 19). These chains are weaker in the chemical extracted gelatin than that of treatment 5. Moreover, it can be seen that in the gelatin extracted by the enzymatic method, the ratio of the α2 / α1 chain is about 2 (the intrinsic ratio in collagen I), which shows that the inherent structure of gelatin is preserved.The highest and lowest amidic wavelength A was obtained for treatment 17 and treatment 19, the highest and lowest wavelength amide I for treatment 5 and treatment 19, the highest and lowest amid II wavelengths for chemical extracted treatments and treatment 17, The highest and lowest ratio of amide III to amide 1454 is related to treatments 5 and 19, and the highest and lowest amount of amide B is related to treatment 19 and 5.The behavior of the viscoelastic modulus of the treatments extracted with the pepsin enzyme (treatment 5, 17 and 19) and the chemically prepared sample showed that at temperatures lower than 20 ° C the storage or elastic modulus (G ') and the loss or viscous modulus (G') decreased with increasing temperature and the elastic modulus was larger than the loss modulus (G' >G'' ) indicating that the samples are still jelly-like (with the exception of treatment 19 that had the weakest gel strength).In all gelatin samples extracted using pepsin and chemical method, first, a relaxation stress index (viscosity increase at the beginning of the graph), and then a thinning non-Newtonian behavior (pseudo-plastic) was obvious during the shear rate. In fact, in the behavior of pseudo-plastic, the viscosity of the fluid is related to the shear rate and has decreased with increasing shear rate. Non-Newtonian viscosity of treatments prepared by the enzymatic method (except treatment 19) was higher than that of the chemically prepared sample at different applied shear rate.
Edris Arjeh; Mikhalil Piruzifard; Sajad Pirsa
Abstract
Introduction Raw sugar beet juice (RSBJ) is an intermediate of sugar beet processing obtaining by diffusion process. The RSBJ contains approximately 85% water, 13% sucrose, and 2% non-sugar compounds (impurities) and its purity ranges from 85 to 88%. Due to the low purity, the RSBJ should be subjected ...
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Introduction Raw sugar beet juice (RSBJ) is an intermediate of sugar beet processing obtaining by diffusion process. The RSBJ contains approximately 85% water, 13% sucrose, and 2% non-sugar compounds (impurities) and its purity ranges from 85 to 88%. Due to the low purity, the RSBJ should be subjected to purification process. The conventional purification occurs in a complex multistage process including pre-liming, main liming, first carbonation, and second carbonation. In liming step, lime milk (Ca(OH)2) is added to destabilize and precipitate the non-sugar compounds. Then the CO2 gas is added to precipitate the lime (as calcium carbonate). Although the application of lime is very well known but some impurities, including phenolic compounds, saponins, proteins and lipids pass through purification processing into the white sugar and cause serious difficulties. Due to the variety of compounds (dissolved or suspended) present in RSBJ and this fact that different processes may remove different types of compounds, various fining agents are required to clarification of raw juices. Bentonite, silica sol, gelatin and activated carbon are four types of natural adsorbents, which have been used in many applications, in different fields and processes, including the food industry. Differences in the nature of ionic charges of juice compounds and the fining agents induce neutralization, and flocculation and result in the removal of them from the juice. Therefore, the purpose of this study was to investigate the efficiency of bentonite, silica sol, gelatin and activated carbon in the removal of impurities (protein, saponin and phenolic compounds) causing floc in acidic beverage and improving the purification indexes of RSBJ (turbidity, color, ash and purity). Floc refers to the cloudy and turbid precipitate that forms in some sugar-sweetened carbonated soft drinks after standing for several days. While flocs are harmless, they are a visible defect and consumers don’t accept the soft drink product for aesthetic reasons. Currently, most researchers assume that saponins are primarily responsible for floc formation. However, there are some studies indicating that protein, phenolic compounds and lipids also play a role in floc formation.
Materials and methods: The RSBJ was regularly obtained from the sugar factory of Piranshahr, Iran. The RSBJ was sampled at the point just before the purification step and immediately transferred to the lab. Fining agents used for clarification including bentonite (Na–Ca Bentonite ERBSLÖH, Geisenheim, Germany), silica sol 15% (Baykisol 15%), Gelatin (type-A; 100 bloom, Erbigel, Germany) and activated carbon (CS-2000, Gostar Ghoumes CO. Iran) was provided by Azar kam Co. Urmia. Iran. For each experiment, 200 ml of the raw juice was subjected to various refining treatments. The RSBJ were refined at 75 °C for 100 min by fining agents. Fining agents were added to beet juice samples according to the preliminary experiments. After the completion of the clarifying process, juice samples were passed through a microfilter (45 µm) to removing formed floc. In order to compare the mentioned treatments (bentonite, silica sol, gelatin and activated carbon) with the conventional method, the RSBJ was also treated with lime-carbon dioxide in four stages (pre-liming (15 minutes at 85 ° C), main liming (15 min at 88 ° C), first carbonation (up to pH 11, 90 ° C) and second carbonation (up to pH 9, 92 ° C)). After applying the treatments, purity and ash content (by conductimetry method) was measured as the main purification indexes for assessing the quality of the juice samples. The total protein (by dye-binding method), total phenolic compound (by Folin-Ciocalteu reagent) and total saponin content (by vanillin-sulfuric acid method) was also determined as the compounds have a key role in formation of acid beverage floc.
Results and discussion: In this study, four refining agents of bentonite, silica sol, gelatin and activated carbon were used to improve the purification indexes of RSBJ and to remove non-sugar impurities causing floc in acidic beverage (such as carbonated beverages). Based on the ash and purity, it was showed that the applied adsorbents (bentonite, silica, gelatin and active charcoal) significantly improved the purification indexes of RSBJ. The results also showed that the ability of bentonite as a negative charged adsorbent was considerably higher than silica-sol in removing impurities (protein, saponin and phenolic compounds) causing floc, and improving the purification indexes (turbidity, color, ash and purity). So, the bentonite treatment reduced protein, phenolic compounds and saponin content of juice by 68, 61 and 40 %, respectively. The combination of gelatin and activated carbon as supplemental clarifiers with bentonite and silica also improved the parameters measured. In general, Bentonite-Activated carbon treatment had the best results, resulting in a reduction of 73, 87 and 85 % in protein, phenolic compounds and saponin, respectively. In this study, mentioned treatments were also compared with conventional treatment (lime-carbon dioxide) and it was observed that new treatments can be a good choice to combine or replace with conventional treatment.
Hesam Omrani Fard; Mohammad Hossein Abaspour fard; Mehdi Khojastehpour; Ali Dashti
Abstract
Introduction: One of the new methods for improving the mechanical properties of bioplastics is the production of blending based bioplastics. Recent studies show that proteins, in combination with starch, form a strong network of hydrogen bonds and intermolecular interactions that resulted stable 3-D ...
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Introduction: One of the new methods for improving the mechanical properties of bioplastics is the production of blending based bioplastics. Recent studies show that proteins, in combination with starch, form a strong network of hydrogen bonds and intermolecular interactions that resulted stable 3-D materials. The big problem in the commercialization of blending based bioplastics is the lack of industrial machinery for the continuous production of bioplastics with the direct use of biopolymers. Industrial production of bioplastics is accompanied by increasing heat along with applying the pressure. It is necessary to know the kinetics of thermal degradation of bioplastics to study thermal behavior at different temperatures in order to design bioplastics processing devices and molding machines, software modeling of processes, mass and energy equilibrium, and optimizing energy consumption in the production process along with improving the thermal properties of the bioplastics.
Materials and methods: In this study, the dynamics thermal decomposition of bioplastics prepared from a mixture of potato whole flour-gelatin and glycerol with a control sample consisting of potato whole flour and glycerol was investigated and compared. The gelatin was extracted from chicken feet using chemical methods. In this research, two isoconversional models including Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models were considered. Using each of these models, thermal decomposition kinetic parameters were calculated for bioplastic samples.
Result and discussion: The results showed that the maximum activation energy of the mixed bioplastics determined 162 and 150 kJ/mol by FWO method at the conversion ratio of 0.9 and 0.5 respectively, while it was 217 kJ/mol at the ratio of 0.6 for control bioplastics. The amounts of kinetic parameters calculated in this study, were able to determine the thermal behavior at different temperatures and the thermal decomposition process. Also, it can help to redesign and optimize the methods of molding and shaping of potato-gelatin based bioplastics by the use of existing machinery in the industry.
Atefeh Rezai Zadeh; Zeynab Raftani Amiri
Abstract
Introduction: Today, the demand for low calorie food based on fruits and easy production and keeping primary features including texture and taste is increasing. Jelly is one of low calorie products which is produced from fruits and other components, and its usage is increasing for human health. Chemical ...
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Introduction: Today, the demand for low calorie food based on fruits and easy production and keeping primary features including texture and taste is increasing. Jelly is one of low calorie products which is produced from fruits and other components, and its usage is increasing for human health. Chemical ingredients and natural features of fruits decrease the cancer. In addition to nutrition and medical values, rheological and texture features affect the general quality of fruit jelly. Gelatin is a protein which is obtained by thermal hydrolysis of collagen and is the main protein of bone, cartilage and skin. The source, animal age and the type of collagen are influential factors on gelatin characteristics. Different gelatins have different thermal and rheological characteristics such as transformation temperature to jelly and melting temperature. The melting temperature of gelatin is lower than human body temperature. In food industry, gelatin is used as an alternative for fat, to improve elasticity and transparency of fruit juices and also is used in production of jelly, chocolate, edible films, and so on. Gelatin quality and its application in industry are mainly because of its rheological features. Global demand for gelatin during recent years increases due to its low cost and solubility in biologic environments.
Materials and methods: In this study, the gelatin from chicken feet was extracted by acidic method using hydrochloric acid 0.5% normal with the rate of 1: 3.22 weight / volume. pH was adjusted to 7 by the use of sodium hydroxyl 1 normal and was dried in an incubator at 450 c for 28 hours. Different tests such as pH, protein, ash, moisture, fat, viscosity, jelly strength, color and rheology were done in gelatin molecule to measure of storage modules (G') and loss modules (G''). Then, the effect of extracted jelly in concentrations of 0 to 1.5 % on the physico-chemical (Brix, humidity, acidity, color, texture) and organoleptic properties of cantaloupe jelly (odor, sweetness, color, appearance, jelly status, transparency, adhesion) were investigated using five point Hedonic scale ranked. Experiments related to cantaloupe jelly were conducted in terms of a completely random design. A one-way analysis of variance and Duncan test (P≤ 0.05), in three replications were used to establish the significance of differences in experimental data’s. The result was performed using the SPSS version 16.0 windows program, and charts were plotted with Excel 2010.
Results and Discussion: The results showed that the average yield of gelatin based on the wet weight was 4.80%, pH value before drying is 3.7, the total amount of protein is 83.95%, the total amount of ash is 0.89%, moisture is 9.66%, fat is 0%, viscosity is 216 centipoise. The strength of jelly is 487g that in compare with other alternatives such as gelatin from chicken skin is 355±48.1 gr, cow gelatin is 299±71.1 gr, fish gelatin including 181 to 263 gr for tilapia, 280 gr for horse mackerel fish, 125 and 177 gram for Sin croaker and Shortfin scad, respectively. The main reason for low level of gelatin in fish skin is the low amount of hydroxyl proline. Thus, it can be claimed that the high gel strength in chicken feet gelatin might be due to lower extraction temperature, strong hydrogen bond and more probably hydroxyl proline. Hydrocolloid solutions are usually viscoelastic; therefore, the level of storage modules (G') and loss modules (G'') is measurable for them. Gelatin from chicken feet exhibited G' greater than the G'' in a wide range of frequencies of the oscillatory test, which have indicated the gel network is high stable. By increasing the amount of gelatin in the cantaloupe juice, transparency and firmness of cantaloupe jelly increased. In the sensory analysis, jellies had not significant differences in the intensity of sweetness. In terms of overall acceptability, the sample containing 1.25 and 1.5 percent of gelatin gained maximum score.
Nasser Sedaghat; Sara Khoshnoudi
Abstract
Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components ...
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Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components are the amount of fats and especially unsaturated fatty acids. Therefore, this nut is highly susceptible to rancidity, especially after roasting. Despite the high quality, raw pistachio and pistachio processing industry at Iran, export of roasted and packaged pistachio, due to low shelf life and drastic changes intaste, is not very successfull. An effort was made to investigate the efficacy of gelatin in comparison with carboxymethyl cellulose (CMC) as edible coating to retard fat oxidation in roasted pistachio.Materials and methods:Five coating formulations were investigated in this study as follow: A) Gelatin (4% w/v) + ascorbic acid (1% w/v): TGA, B) CMC (1% w/v)+ ascorbic acid (1% w/v): “TCA”, C) ascorbic acid (1% w/v): “TA”, D) Gelatin (4% w/v) + CMC (1% w/v) + ascorbic acid (1% w/v): “TCGA” and 5) control sample (uncoated sample): “TCO”.Roasted pistachio nuts were coated by dipping the nuts in the coating solutions. For each treatment, 100 gram of pistachio nuts were packaged (BOPP/Al/CPP, 80 micron plastic bags) in triplicate. The physicochemical analysis included measurement of free fatty acid (FFA), peroxide value (meq.O2 kg-1),hardness (N), moisture (%) and the sensory evaluation (texture, rancidity, taste and overall acceptability) were performed on coated and uncoated pistachio nuts stored at 35 and 50 °C. The nuts were sampled on the 0th, 1st, 2nd and 3rd month of storage. Data was analyzed using Minitab 16. Analysis of variance (ANOVA) and general linear models (GLM) procedure wereused to compare the mean values of each treatment and Significant differences between the means of parameters were determined based on the results of the Tukey’s multiple range test (p0.05).FFA content of TCGA sample was significantly lower than other samples.The highest protection, according to these criterions, was provided by gelatin-CMC coating containing ascorbic acid.The control samples exhibited more bitterness and off flavor than the coated samples, seemingly on account of chemical reaction and second products of oxidation content. Instrumental and sensory hardness of pistachio nuts which were coated with gelatin and/ or CMC (TCA, TGA and TCGA) were significantly (p
Mehdi Jalali; Mohammad Hossein Hadad Khodaparast; Eisa Jahed
Abstract
In this study , response surface methodology and face central composite design in order to investigate decolorization and clarification extraction of Kaluteh date was used for the production of liquid sugar. The optimum amount of bentonite ( 1-3 g/l ) and gelatin ( 0/02-0/08 g/l ) was determined that ...
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In this study , response surface methodology and face central composite design in order to investigate decolorization and clarification extraction of Kaluteh date was used for the production of liquid sugar. The optimum amount of bentonite ( 1-3 g/l ) and gelatin ( 0/02-0/08 g/l ) was determined that the desired amount of bentonite and gelatin , 3 and 0/05 ( g/l ) , respectively. To determined the optimum conditions for maximum activity of these two compounds for clarification with regard to fixed amount of bentonite and gelatin , three factors determine the temperature ( 30-70 °C) , pH ( 4-6 ) and time ( 40-120 min ) was implemented. Parameters consists of the colors , ash and absorbance. Bentonite and gelatin at low temperature and pH with over time , more active and reduce the mount of impurities. The least amount of this responses for the color at 420( nm) , ash and absorbance at 660 (nm),4302 Icumsa ,0/421 % and 0/059 ,respectively. By comparing amounts in the optimum point the clear syrup by bentonite and gelatin ,the initial syrup ,it was found that this technique able to reduce the mount syrup color ,ash and absorbance ,68/25 % , 8/7 % and 89/46 % ,respectively.
Masoud Rezaei; Ali Motamedzadegan
Abstract
To investigate the optimum conditions for extracting gelatin from whitecheek shark (Carcharhinus dussumieri (skin, response surface methodology (RSM) has been adopted. In this research, the effect of NaOH concentration (0.01-1 N), HCl concentration (0.01-1 N), and extraction time (3-8 h) on dependent ...
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To investigate the optimum conditions for extracting gelatin from whitecheek shark (Carcharhinus dussumieri (skin, response surface methodology (RSM) has been adopted. In this research, the effect of NaOH concentration (0.01-1 N), HCl concentration (0.01-1 N), and extraction time (3-8 h) on dependent variables, yield and melting point of the skin gelatin have been studied using central composite design. Based on the individual regression models, predict values of multiple response at optimal condition were %23.222 (yield), and 32.224 °C (melting point). The best pretreatment conditions to get to the optimum properties were 0.01 N NaOH, 0.135 N HCl and 3 h extraction time. The results showed that, NaOH and HCl concentrations had significant effects, but extraction time had no significant effect on gelatin extraction yield and its melting point.
