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
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.
Reza Mobasserfar; Seyed Ali Mortazavi
Abstract
Introduction: Doogh is one of the most important and most widely consuming fermented traditional Iranian milk products, which is being prepared from the healthy milk by using the activity of certain lactic acid bacteria and molds under the especial conditions. Streptococcus thermophilus and Lactobacillus ...
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Introduction: Doogh is one of the most important and most widely consuming fermented traditional Iranian milk products, which is being prepared from the healthy milk by using the activity of certain lactic acid bacteria and molds under the especial conditions. Streptococcus thermophilus and Lactobacillus bulgaricus are used as starter culture for milk fermentation. The fermented dairy products have long storage life and constitute an important part of the milk's per capita consumption. For this reason, studying the different methods in order to improve the quality of these products is crucial. By considering the fact that the strong thermal treatments damage some components of milk such as protein and vitamins, using the membrane filterations decrease the need to impose the intense thermal conditions which result into the relative loss of nutrients. On the other hand, using the membrane filters not only increase SNF (solid non-fat) and the percentage of protein but also lead into the production of less-lactose milk as well, the production of less-lactose products, in addition to their nutritional value for some people, have especial benefits for improving the quality. As follows, UF filters in 10-2-10-1 diameter separate the bacteria, fats and protein when milk is passing with a pressure about 1-10 bar but also they pass the minerals such as salts and water which are being removed as permeate and the concentrated milk is called “Retentate”. Materials and methods: Materials provided in this study were including: Starter culture (No: 505 form Danisco, USA), Lactic acid (1.00366) with a degree of purity level more than 95%, NaH2PO4*2H2O (1.06345) plus the cultures' environment and the chemical substances from MERCK Company. HPLC system (Agilent, 1100 series, USA), Rheometer (Anton, MCR300, Austria), Milk analyzer bar (Azmalaban, MCC, Iran), pH meter (Knick,766, Germany), Digital scale 0.001 (AND,GF4000, Japan), Psychrometer (Sartorius, MA45, Germany), Oven (memmert, UM400, Germany), Centrifuge (Funke Gerber, Nova safety, Germany), Kjeldahl (Gerhardt, KB, Germany), Refrigerated incubator (WTW,TS606-6/2-i, Austria), Incubator (memmert, BM400, Germany), Autoclave (RT-2, Reyhan Teb, Iran). In the present study the effect of a decrease in lactose percentage on the durability, flavor and sensory (organoleptic) properties of produced doogh on the 1st, 23rd and 46th day’s after production time in comparison to control ones, was investigated. The changes of acetaldehyde levels were measured using Gas chromatography mass spectroscopy. In this study, milk was passed through UF filters in three consecutive days and its lactose level was decreased by about 2%. After that fermentation and standardization of doogh based on the amount of fat and solid-nonfat has been done. All tests were repeated 3 times and the comparison of averages has been done by using LSD test (p= 0.05 %). Results were expressed as mean ± SE. Values were the average of triplicate experiments. Significant differences between the results were calculated by analysis of variance (ANOVA) with the help of SPSS software version 20. Differences at P<0.05 were considered to be significant. Also the obtained data for the rheological experiments was processed using software such as Excel 2010 and SPSS software version 20 to determine an appropriate mathematical model. And in this case, the linear and nonlinear regressions were used. Results & discussion: Results showed that by increasing the storage time, the acidity and pH changes and the acetaldehyde amount of produced doogh was less than those of the control samples. Additionally flavor and sensory properties improved considerably. Based on the findings of this research, it seems that the reduction of lactose and the decrease of lactic acid bacterial activity can play an important role in increasing the durability time, improving the sensory properties and enhancing the quality of doogh. It was determined that the decrease of lactose using ultrafiltration to the control sample not only indicates the significant changes in most considered variables but also there are these kinds of changes during the durability time. In addition, the significant and slow changes of pH to the control sample due to the decrease of lactic bacteria activities show the least qualitative and flavor changes over the durability time. And also it was specified that by increasing the activities of lactic bacteria, the amount of acetaldehyde will increase but by decreasing this activity, the level of acetaldehyde will decline. This issue has a direct relationship with the changes of lactose's amount. The post-filtration doogh due to its high amount of proteins shows high viscosity and concentration and for this reason, the attention of panelists in the sensory evaluation was directed toward choosing the post-filtration doogh instead of the pre-filtration one. Therefore, it can be concluded that the decrease of lactose using ultrafiltration has a main role in improving the quality of the product and also the tendency of the consumers.
Mohammadmahdi Seyedabadi; Mahdi Kashani-Nejad; Alireza Sadeghi Mahoonak; Yahya Maghsoudlou; Fakhreddin Salehi
Abstract
The turbidity of sour orange juice after juice extraction affects on quality, shelf-life and concentration of juice. Therefore, juice clarification is an important operation in the fruit processing industry. The goal of this study was evaluating the effect of membrane operation parameters including pressure ...
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The turbidity of sour orange juice after juice extraction affects on quality, shelf-life and concentration of juice. Therefore, juice clarification is an important operation in the fruit processing industry. The goal of this study was evaluating the effect of membrane operation parameters including pressure (120-220 kPa) and temperature (25-35 ºC) on the permeate flux and hydraulic resistance of sour orange juice during membrane clarification. Response surface methodology (RSM) was used to optimizing the operating parameters. Results of the experiments showed that the permeate flux was raised with increasing of temperature, but total hydraulic resistance (RT), concentration polarization resistance (Rcp) and gel layer resistance (Rg) was decreased in mentioned condition. The permeate flux, membrane resistance (Rm), RT, Rcp and fouling index was raised with increasing in pressure. The Rm and fouling index are showed different behavior depending on temperatures level. Results of process optimization indicated that the best conditions to maximize of permeate flux, and to minimize of fouling index and RT achieved at 35 ºC and 120 kPa for a maximum desirability of 0.761.
Food Engineering
Seyed Mohammad Ali Razavi
Abstract
Viscosity (µ) and density (ρ) are important physical roperties for analysis of membrane processes performance and for designing a new membrane process. In addition, the energy requirement for fluid pumping is depend on these two physical properties magnitiude. In this study, firstly, the effects ...
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Viscosity (µ) and density (ρ) are important physical roperties for analysis of membrane processes performance and for designing a new membrane process. In addition, the energy requirement for fluid pumping is depend on these two physical properties magnitiude. In this study, firstly, the effects of different process factors such as transmembrane pressure (51, 101, 152, 203 and 253 kPa), temperature (30,40 and 50ºC) and the effects of physico-chemical properties such as milk pH (6.67, 6.43, 6.25 and 5.97), milk fat percent (0.09, 1.19, 2.4, 3.26) on the viscosity and density of permeate have been considered. Two linear multiple regression models were then developed by Sigmastat software for prediction of µ and ρ during milk ultrafiltration. The experimental results showed that µ and ρ decreased as fat percent or temperature increased. pH had no considerable effect on µ and ρ. Furtheremore, increasing transmembrane pressure to 152 kPa led to an increase in both µ and ρ, while further increasing to 253 kPa resulted in a decrease in both µ and ρ. The statistical modeling results showed that the viscosity is only significantly depend on temperature and there was an excellent agreement between actual and predicted data (R=0.976), whereas the density is siginificantly depends on both temperature and fat percent and there was a good agreement between experimental and predicted data (R=0.904).
