مجله علوم غذایی و تغذیه
سال پانزدهم شماره 4 (پاییز 1397)

The demand for cheese flavours has increased due to consumer request for convenience food that possesses cheese flavour. The best method for producing economic and consistent cheese flavours is through enzyme-modified cheeses production. The aim of this study was to produce enzyme extracts from Lactobacillus casei, Aspergillus niger and Aspergillus oryzae and measure the activity of lipase and proteinase of the produced enzyme extracts and employ them in cheese production. Lactobacillus casei, Aspergillus oryzae and Aspergillus niger are three kinds of microorganisms that were used in this study for the production of EMC. Solid state fermentation has been used for the production of lipolytic and proteolytic enzymes to preparation enzyme from molds and cells of L.casei were disintegrated by sonication and Lysozyme. In order to produce EMC, cheese-slurry was provided and incubated at 37ºC for 48h with crude enzyme and then assessment of proteolysis and lipolysis in the EMCs were investigated. The results indicated that L.casei has lipase and protease enzyme activities of about 103 and 80U/ml respectively, while the lipase enzyme activities was about 240 U/ml for A.niger and protease enzyme activities was about 155U/ml for A.oryzae. Assessment of proteolysis and lipolysis in the EMCs were investigated by the determination of soluble nitrogen ,tricholoracetic acid soluble nitrogen, total free amino acids and GC. The greatest levels of proteolysis and lipolysis were observed in the EMC3. No statistical difference was observed between the overall acceptability of EMC3 and commercial Cheddar cheese as
judged by the sensory evaluation panel members. The results of this research showed that the mixture of enzyme extract can be very effective on proteolysis and lipolysis in Iranian white cheese and also they can be used to produce EMC in much shorter ripening period and with improved flavor.

ntroduction: Soybean is recognized as a good source of essential nutrients including protein, oil and several bioactive compounds and soybean has the potential to be used as snack and roasted nut, but most significant factor responsible for such limitation is probably considered as the characteristic flavor of soybean. Raw soybean has beany, bitter and astringent flavors. Therefore to improve its consumption, the particular flavor of raw soybean must be removed. Roasting might be considered as one of the best methods for this object. In this study, the infrared roaster is designed and soybean has been prepared and roasted according to the experimental condition. In this work, an artificial neural network model was developed for modeling of moisture content of soybean snack during infrared roasting. In order to do this, infrared lamp powers of 250, 350 and 450 W, distance between lamp and sample of 4, 7 and 10 cm and roasting time of 30 min were considered as the inputs and the amount of moisture ratio (MR) was estimated as the output. In addition, three different mathematical models were fitted to the experimental data and compared with the ANN model. Based on these results, artificial neural network model for MR with one hidden layer, Sigmoid function as the transfer function, Levenberg-Marquardt method as the learning rule, 4 hidden neurons, 55% for training subset and 25 and 20 percent for each of validation and test subsets respectively had the best over fitting. The determination coefficient (R2) and root mean square error (RMSE) computed for the ANN model were 0.9992 and 0.01099and for the best mathematical model (Two term model) were 0.9776 and 0.02758, respectively. It was concluded that the artificial neural network model satisfied the work better than the mathematical model concerned with soybean snack roasting.

Fat reduction adversely affects different properties of cheese. Transglutaminase treatment of low-fat milk incorporated with whey proteins makes it possible to develop a low-fat white-brined cheese with rheological properties similar to the full-fat counterpart. The objective of this study was to monitor the changes in proteolysis and lipolysis indices of transglutaminase–treated low-fat white-brined cheese during ripening. A control full-fat (3% fat), a control low-fat (1% fat) and an enzyme-treated low-fat (1% fat, 0.9 U transglutaminase/g protein, 5% whey protein isolate/L milk) white-brined cheese were produced and their physicochemical properties, proteolysis and lipolysis indices, FFA profile and organoleptic attributes were studied after 3, 20, 40 and 60 days. The proteolysis and lipolysis indices of all samples showed an increasing trend during ripening (p<0.05). The development of proteolysis and lipolysis in white-brined cheese with reduced fat content was noticeably slower than its full-fat counterpart (p<0.05). Transglutaminase treatment of low-fat milk incorporated with whey proteins retarded the syneresis of resultant cheese and hereby promoted its extent of proteolysis and lipolysis (p<0.05). The decreasing rate of short-chain free fatty acids production was more pronounced than that of medium- and long-chain free fatty acids, due possibly to their contribution to production of flavor compounds. Flavor of enzyme-treated low-fat cheese was considerably improved during ripening (p<0.05) but was less appreciated by consumers than that of control full-fat sample (p<0.05). Transglutaminase treatment of low-fat milk incorporated with whey proteins results in a low-fat white-brined cheese with accelerated proteolysis and lipolysis and thus, more desirable organoleptic properties.

Protein hydrolysates are compounds with low molecular weight that after entering the body are easily absorbed and play important biological roles in cellular levels. The most important functions of bioactive compounds are antioxidant, antimicrobial, anticancer activities and enhance the immune system. The main objective of this study was to produce cotton seed protein hydrolysate using pepsin enzyme that was optimized by response surface methodology. The factors investigated in this study were temperature (30-40◦C), time (2-5h) and enzyme/substrate ratio (0.5-2%) in order to obtain maximum antioxidant activity. The antioxidant activities were investigated using 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging capacity, total antioxidant capacity, reducing power and chelating activity. All of the experiments were designed according to the central composite design. Each of the studied variables had a significant effect on the responses (p<0/05). The optimal conditions to achieve maximum antioxidant activity were temperature of 31.1◦C, time of 5h and enzyme/substrate ratio of 1.75%, respectively. Under these conditions, (DPPH) free radical scavenging capacity, reducing power, chelating activity, total antioxidant capacity and degree of hydrolysis were 83%, 0.158 Å, 70%, 1.99 mmol α- tocopherol/mL and 31.75%, respectively. Cotton seed protein hydrolysates have exhibited good antioxidant activity and might be employed as a natural antioxidant in food products and formulations.

Coeliac disease is an autoimmune digestive disease that is caused by the digestion of gluten and the only treatment of this disease is a gluten free diet. In this study, batter rheology, and physical, sensory and crumb color properties of gluten free cake based rice flour were studied. The rice cake batter containing different percentages of Balangu seed gum (at four levels 0, 0.5, 1 and 1.5 %) were prepared and their rheological properties were evaluated. Cake batter viscosity by a brookfield rotational viscometer, physical characteristics by standard methods, cake crumb color (L*, a* and b* values) by image processing method, and sensory evaluation (overall acceptability) by 9-point hedonic method were evaluated. By increasing Balangu seed gum in the formulation of rice cake, the viscosity of batter was increased. Rice cakes batters were as non-newtonian fluids and pseudoplastic (shear-dependent) and thixotropic (time-dependent) type. The results indicated that by increasing the Balangu seed gum from 0 to 1.5 %, rice cake batter viscosities at shear rate of 10 s-1 were increased from 13.16 to 22.32 Pa.s. The moisture content and volume of cakes were increased by increasing gum concentration. According to the sensory results, samples containing 1.5 % Balangu seed gum had the highest total acceptance score. By increasing Balangu gum, the brightness of cakes has been increased due to the increase in volume and the yellowness decreased. The L*, a* and b* indexes for the sample containing 1.5 % gum were 85.01, -1.37 and 37.56, respectively.

Bifidobacterium bifidum is a beneficial probiotic usually utilized as supplement in food and food products. Beta-carotene is also a food supplement with antioxidant activity. These compounds are usually susceptible and have short durability, therefore, microencapsulation improves the sustainability. In the present study, the effect of encapsulation using “freeze drying” method was investigated on survivability of Bifidobacterium bifidum and stability of beta-carotene. Emulsified beta-carotene in a solution of sodium caseinate and carrageenan were prepared and mixed with a dense suspension of Bifidobacterium bifidum. The solutions were then dehydrated with a freeze dryer device. The viability of bacterium and durability of beta-carotene in encapsulated samples were compared with non-encapsulated samples at the day zero and during storage at 4 and 25 °C for one month and also in simulated gastric acid situation. The results showed that encapsulation could increase the viability of encapsulated Bifidobacterium bifidum and durability of beta-carotene. The presence of beta-carotene in encapsulated samples significantly (P˂0.05) increased the survivability of encapsulated bacterium during storage. Microencapsulation had also a significant positive impact (P˂ 0.05) on the survivability of bacterium in simulated gastric conditions. Microencapsulation of bifidobacterium bifidum and beta-carotene using casein and carrageenan could improve the survivability of bacterium and stability of beta-carotene during storage and in simulated gastric acid situation.

Introduction: The addition of antioxidants is one of the ways to protect the oil from oxidation. The aim of this research is to obtain ferula persica plant extract using supercritical fluid method and measure the phenolic compounds and tocopherols and also to evaluate the effect on the oxidative stability of sunflower seed oil during storage. Materials and Methods: Using supercritical fluids (SCF), the ethanolic extracts at different concentrations (100, 1500, 2000 and 2500 ppm) were prepared. Total amount of phenolic compounds and tocopherols in the extracts were determined by the Folin–Ciocalteu and spectrophotometry procedures, respectively. The antioxidant activity was evaluated and the concentration of 2500 ppm showed the highest antioxidant activity, therefore, this concentration was selected and added to sunflower seed oil. The oil was kept at room temperature for 60 days and peroxide value, carbonyl number, oxidative stability index, total polar compounds and acid value were measured every 15 day and compared with the synthetic antioxidant (TBHQ 100 ppm). Results: The concentrations of phenolic compounds and tocopherols in the SCF extract were determined and found to be 1495.81 mg as gallic acid and 58.6 mg alpha-tocopherol per 100 gram of extract. Conclusion: Ferula persica extract at the concentration of 2500 ppm due to the presence of both phenolic compounds and tocopherols exhibited antioxidant acivity in sunflower seed oil and have the ability similar to TBHQ that results in increased oxidative stability of the substrate, therefore, Ferula persica that is a natural product might be considered as a potent antioxidant to improve the stability of oils and fats.

Marinated olives using various herbs, spices and pastes have become quite popular and demanding. This research work is concerned in providing new formulations of marinated olives using various concentrations of tamarind and oregano. Chemical evaluations concerned with pH, acidity, salt and antioxidant activities and microbiological evaluations concerned with lactic acid bacteria, molds and entrobacter followed by sensory evaluations related to aroma, color, taste and texture were carried out according to the defined standard. The results indicated a decrease in pH and consequently an increase in acidity with a statistical analysis of 95% (p<0.05) using Duncan procedure. Both pomegranate paste and tamarind contain high concentrations of phenolic compounds that could act as primary antioxidants. By increasing tamarind concentration in relation to pomegranate paste, lactic acid bacteria were observed. The application of dried oregano increased molds growth as compared to the control without oregano. Salt concentration within the permitted limit had little effect on the growth of microorganisms. The samples containing 10% tamarind and 1% oregano scored the highest regarding the taste and flavor of the samples. The texture and color of the formulated product were not affected during 120 days of storage at 4 C.

Cinnamon and its extract contain different chemical components that might possess both antimicrobial and antioxidant activities. This study was carried out to evaluate some chemical, microbial and sensory quality changes of common carp fillets treated with cinnamon extract during refrigerated storage. The fish fillets (approximate average weight of 100g) were prepared and divided into three groups. First and second groups were dipped in cinnamon extract with the concentration of 1.5 and 3%, respectively. The third group; the control, was dipped in distilled water. Fish fillets were wrapped in polyethylene package during storage at refrigeration temperature (4±1°C). The chemical tests consisted of peroxide index, thiobarbituric acid, total volatile basic nitrogen and microbial tests including total viable count, psychrotrophic count with sensory evaluation, were performed over the period of 21 days. The results showed that cinnamon extract with 1.5% concentration delayed oxidation and microbial spoilage, while keeping the sensory evaluation score. This concentration was unable to maintain bacterial spoilage, thiobarbituric acid, total volatile basic nitrogen and sensory indices up to the proposed acceptable limit on fourteenth day of the trial. Cinnamon extract at 3% concentration retarded the spoilage indexes in the acceptable limit up to fourteenth day of the cold storage. The cinnamon extract with 3% concentration might be used as a natural antioxidant to retard the spoilage process of fish fillet . However, this concentration was unable to maintain the freshness indexes of the treated fish fillets until the 21-day of the experiment.

The adverse effects of trans fatty acids on health during hydrogenation demands trans free products. Trans interesterification might be considered a process to solve this problem. The aim of this study is to interesterify palm stearin and canola to provide a hardened media and then investigate the physicochemical characteristics of the product. Binary blends of palm stearin/canola oil (in ratios of 10:90, 20:80, 30:70, 40:60 and 50:50 w/w) were interesterified using sodium methoxide as an alkaline catalyst. The changes in fatty acid composition, the 2-position arrangements of fatty acids, free fatty acids content, peroxide value, soap content, induction period at 120 °C (IP120), slip melting point (SMP) and solid fat content (SFC) of fat blends, before and after interesterification, were investigated. Studies on fatty acid composition before and after interesterification showed that the process did not affect the chemical structure of fatty acid and the concentration of trans. All blends were trans-free and contained high essential fatty acids contents. Studies concerned with the 2-position arrangements of fatty acids, have shown that the expected random equilibrium has been achieved after 60 min of processing. Interesterification has modified the melting properties of fat blends by decreasing SMP and SFC. Interesterification has modified the melting properties of fat blends by decreasing SMP and SFC. Interesterified blends of palm stearin/canola oil at the ratio of 10:90 for liquid margarine, 20:80 and 30:70 for soft tub margarine, 30:70 and 40:60 for Iranian vanaspati and 50:50 for ice-cream formulation showed desirable characteristics.