فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال هشتم شماره 2 (تابستان 1398)

In this study, vanillin release from multilayered microcapsules consisting of isolated soy protein, modified starch, and chitosan produced by spray dryer was investigated. Vanillin release was studied using a mouth simulator. The parameters included oral variable such as saliva and the tension on vanillin release. To examine the release of vanillin, the release of these microcapsules (one and two-layers) at 37 °C and pH=6.8, as well as frequent chewing (0, 30 and 55 rpm) were investigated. The results of the release of single (isolated soy protein) and twolayers (modified starch) microcapsules according to the Korsemeyer- Peppas equation showed that the two-layer microcapsules were less diffusion coefficient than the one-layer microcapsules. Mean dissolution time for two-layer and one-layer were calculated 1.24 and 1.08 h at 37 °C, respectively.Therefore, at the same conditions (adding saliva and shear stress), the release rate of vanillin from the two-layer microcapsules was lower than the one-layer microcapsules due to the modified starch coating around the shells and the increase in the thickness of the shell of the two-layered microcapsule, which reduces the release velocity of vanillin from the two-layer microcapsules.

This study determined the optimal conditions for enzyme-assisted gelatin extraction from sheep skin waste using the effects of three variables: enzyme concentration (0.5-2.5%), hydrolysis time (60-240 min), and extraction temperature (60-80 °C). The impact of these three variables was studied on extraction, yield, gel strength, viscosity, degree of hydrolysis, melting point and SDS-PAGE, and the results were analyzed by using the central composite design (CCD) and response surface methodology (RSM). Also the analysis of variance table showed that the lack of fit was not significant for all response surface models at 95%. The results showed that enzyme concentration 0.5%, hydrolysis time of 166 min, and extraction temperature 60 °C are the desirable condition for optimal extraction (11.03%) and optimal degree of hydrolysis (23.00%). In addition, the effects of these three variables on gel strength, viscosity and melting point were significant, and in optimal conditions, gel strength was measured as 175.33 g, viscosity as 3.26 Mpa/sec, and melting point as 25.39 °C.

The growing demand of consumers for healthy foods has created a great incentive for the advancement of new food products around the world. Functional foods, particularly synbiotic products, are one of these products. In this research, the effects of microbial transglutaminase enzyme (MTG, 0-1 units per gram of milk protein), demineralized whey powder (DWP) solution containing 34% DWP (0-16%) and inulin (0-2%) on the physicochemical, sensorial and microbial properties of Iranian white ultrafiltrated symbiotic cheese was investigated using the response surface method (RSM). For cheese production, Lactobacillus acidophilus LA5 was used as probiotic and inulin and DWP solution were used as prebiotics. The results showed that by increasing of MTG concentration, moisture content of cheeses increased significantly (P<0.05), but acidity and other physicochemical properties and sensory attributes did not change noticeably. By increasing DWP substitution with ultrafiltrate, fat and protein values (P<0.01) and all the sensory attributes (P<0.05) significantly decreased but acidity did not change remarkably. Furthermore, with increasing inulin, acidity, color and appearance, odor and flavor (P<0.05) increased and moisture content (P<0.01) decreased significantly. By increasing of MTG concentration, the number of probiotic bacteria reduced significantly but addition of DWP solution (P<0.05) and inulin (P>0.05) had adverse effect and enhanced it. The optimization results showed that by using 0.43 U/g protein of MTG, 8.24% DWP solution and 0.71% of inulin, an Iranian white symbiotic ultrafiltrated cheese with appropriate physicochemical and sensory properties could be produced. The optimized cheese had adequate total acceptability (7.76 score) and high probiotic count (6.96 logcfu/g).

Walnuts contain many nutritional compounds, including omega-3, various vitamins, especially vitamin E and types of minerals. Therefore, the development of foods based on walnut and studies on chemical and microbial stability during storage, is very important. In this research, the effects of various concentrations of BHT (three levels 100, 150 and 200 mg/L) on changes in peroxide value and acid value of walnut butter, as well as the effect of two types of preservatives of benzoic acid and sorbic acid, each in two levels (400 and 800 mg/kg) were separately and mixed, on the total count of microorganisms and the count of mold and yeast of walnut samples during 75 days of storage at ambient temperature is investigated. The results of this study showed that by adding BHT at 200 mg/L, the peroxide value decreased significantly compared to the control sample. After production, acidic value was 0.3% and it rose to 0.4-0.5% after 75 days of storage. Also, benzoic acid was more effective in reducing total bacterial count and counting mold as well as yeast during storage in comparison with sulfuric acid.

In this study, the effect of emulsion containing sugar alcohols and particle size on increasing the melting point of the chocolate in semi-industrial conditions was investigated. Formulation containing PGPR emulsion, cocoa butter, water, isomalt and maltitol was added to a chocolate with a particle size of 20 and 30 m. Texture, melting point and sensory properties (color, odor, taste, oral sensation and overall acceptance), moisture content and water activity were analyzed for chocolate formulated with PGPR emulsion, cocoa butter, water, isomalt and maltitol. The chocolate was compared with the control chocolate. The results showed that the use of maltitol and isomalt significantly increased the moisture content and water activity of the samples (P<0.05). Significant differences were observed between the treatments in terms of hardness of the tissues, which indicated a decrease in hardness by increasing the emulsion of sugar alcohols (P<0.05). Sensory properties showed that maltitol was similar to the control sample in terms of flavor and had a higher rate of oral melting compared to isomalt in all concentrations in color, all treated samples were brighter than control samples. There was no significant difference in the overall acceptance of the samples (P>0.05). In general, due to the insignificant effect of this emulsion formulated in the overall acceptance of sensory properties and its significant effect on increasing the melting point, these materials can be used in the production of heat -resistant chocolate in tropical areas.

Pear damage is one of the main causes of the loss of fruit quality. Bruises occur during dynamic and quasi-static loading, which causes damage to the healthy tissue of the fruit. In this research, pears were placed under quasi-static loading (thin edge and wide edge) and dynamic loading. Then they were stored in 5, 10 and 15 days and after each storage period, using the CT-Scan non-destructive technique the bruise percentage was estimated. In this study, multi-layer perceptron artificial neural network (MLP) by 2 hidden layers and 3, 5, 7 and 9 neurons hidden layers was selected for modeling of loading force and storage period to predict bruise rate. The highest R2 values for training and testing for quasi-static loading of thin edge and wide edge in a 9-neural network were training Thin-edge=0.91, test Thin-edge =0.99 and training Wide-edge=0.95, test Wide-edge =0.99. For the dynamic loading of a network with 3 neurons in the hidden layer has the highest value (training Wide-edge=0.98, test Wide-edge =0.99). For learning (9 neurons) quasi-static loading thin edge (7 neurons) quasi-static loading wide edge and dynamic loading (7 neurons) have been the best network. According to the results obtained for R2, RMSE and learning cycle, it can be said that the neural network has the ability to predict the bruise percentage to an acceptable level for pears.

This study was aimed to investigate the best features extracted from images to determine the best technique for qualitative classification of green tea by using meta-heuristic algorithms. Five different classes of green tea were evaluated according to the standards of the Institute of Standards and Industrial Research of Iran. After receiving the images of different green tea classes in the computer, 6 square blocks were extracted from each of the original color images. These image blocks were transformed from RGB to gray scale images. One-level discrete Haar wavelet filter was applied to the gray images and 4 wavelet subimages were obtained. Co-occurrence matrices were calculated for each wavelet subimages and 17 common texture features in the image textural studies, were extracted from subimages (totally 68 texture features for each block image). By using principal component analysis, 8 feature components were produced from the original features and used for the separation of 5 groups of green tea. The results showed that algorithms of artificial neural networks, support vector machine and decision tree were capable of qualitative classification of green tea with high accuracy. However, Bayesian network did not have acceptable performance. According to the evaluation statistics, the multilayer perceptron artificial neural networks (with Kappa statistic, root mean square error and classification accuracy of 0.90, 0.42, and 99.17%, respectively) was the best classifier. Based on the results of this study, the use of machine vision and texture features extracted from image wavelet subimages is a suitable technique for the qualitative classification of green tea.

The aim of this study was to evaluate the effect of dietary enrichment with lemon pomace powder on lipid and protein oxidation of carp fillets during storage at refrigerator. Group 1 of carps as control group was fed with basic diet and groups 2, 3 and 4 were fed with 1.5, 3 and 5% lemon pomace powders, respectively. After the end of the study (4 weeks), 10 fish from each group were randomly captured and stored at 4 °C for 3 days. At the capture time and during storage times, 24, 48 and 72 hours at refrigerator, lipid and protein oxidation parameters of the muscle were evaluated. The results indicated a significant difference in the mentioned indices in group 4 compared to other groups (P<0.05). Therefore, a diet containing 5% lemon pomace powder is suggested as a natural antioxidant in carp diet to improve the oxidative status and increase the shelf life of the fillet during storage at 4 °C.