Journal of Food Technology and Nutrition
Year:2019 | Volume:16 | Issue:4 (64) |Papers Count:11

Introduction: One of the scenario for separation of biotechnology products is the application of aqueous two-phase systems (ATPS) rather than traditional extraction by using solvent. The ATPSs are applicable method for separation and purification of biomolecules mixture. The ATPS can be applied for protein purification of biomolecules from suspension broth. The goal of the present research is the study of partitioning of-amylase in polymer-salt aqueous two-phase system composed of polyethylene glycol with molecular weight of 1000 and tri-sodium citrate salt as a biocompatible salt. Materials and Methods: The aim of this research is to study partitioning of α-amylase enzyme in an aqueous two phase system. The system consists of polyethylene glycol (PEG) with molecular weight of 1000 and tri-sodium citrate that is a biocompatible salt. Results: The results for partitioning of enzyme in ATPS has been modeled and statistically analyzed; and indicated that the partition coefficient of-amylase in the system has the maximum amount of 2. 681. Conclusion: In this research it has been proved that ATPS components concentration has an effect on the enzyme partition coefficient. Using experimental results,-amylase has a great tendency to be placed in the PEG rich phase.

Introduction: The addition of date syrup might be considered as an ideal way to produce a functional food. This study was carried out to determine the effects of the addition of date syrup on sensory and physicochemical properties of synbiotic yogurt. Materials and Methods: Date syrup was added at three different concentrations (5, 10 and 15% w/w). The samples were subjected to physicochemical analysis (pH, titrable acidity, syneresis and dry matter) and sensory evaluation (texture, formidability, flavor, color and overall acceptability) according to the standard methods. Results: Theresults showed that date syrup significantly increased the viability of the probiotics (P<0. 05). The most count of probiotic bacteria was observed on the seventh day. After a few days the acidity was increased and the addition of each level of date syrup caused the acidity to be significantly increased (P<0. 05). The results showed that pH value of the samples containing date syrup significantly decreased in the first and last days (P<0. 05). There were significant differences in syneresis between control and date syrup yogurt during seventh and last days (P<0. 05). The amount of dry matter was higher than control samples (P<0. 05). Yogurt samples with 15% date syrup achieved the best organoleptic taste in sensory evaluation. Conclusion: Utilization of date syrup in low fat yogurt especially at 15% concentration of it, caused an increase in the viability of Lactobacillus acidophilus and decreased syneresis and improved the sensory acceptability. Eventually, fortifying yogurt with date syrup produced acceptable yogurt with beneficial health effects.

Introduction: Aflatoxins are secondary metabolites produced by some species of Aspergillus fungus on agricultural products. They have great health, medical and economic significance due to mutagenic and carcinogenic effects on consumers. The purpose of this study is to compare ultraviolet and tungsten rays in reducing aflatoxin B1 in rice flour. Materials and Methods: Contaminated rice flour with two concentrations of 50 and 100 ng/g of aflatoxin B1 that produced by Aspergillus flavus in the laboratory were illuminated at 5 times 10, 20, 30, 40 and 50 minutes, with two different distances of 7 and 14 cm from ultraviolet light source with wavelength 366 nm and tungsten 100 W. Aflatoxin content was measured using competitive ELISA in two replications. Aflatoxin levels were compared with control samples by SAS (Release 9. 1, SAS Institute Inc., Cary, NC) software using Duncan test. Results: The results showed that maximum (67 and 68%) and minimum (14 and 18%) reduction of aflatoxin B1 occur after 50 and 10 minutes irradiation at 7 and 14 cm, by ultraviolet and tungsten light, respectively. The initial concentrations of Aflatoxin B1 did not affect the test, but reducing the distance to the source of light and increasing exposure time led to a further reduction of aflatoxin (P≤ 0. 01). Conclusion: Reducing the distance between rice flour and ultraviolet or tungsten ray source decreases aflatoxin further. On the other hand, the longer exposure to radiation, the more aflatoxin declines. The use of these rays can be considered in aflatoxin mitigation of food.

Introduction: In this study, according to the increasing production of meat products with higher nutritional value, the flour of sesame press cake, which is the waste of sesame seed oil extraction factory, was used as a low-priced supplement and rich in protein, fiber and minerals, together with soy meal in the formulation of sausage of 40% chicken meat. Materials and Methods: Soy and sesame meal at concentrations of 2, 4, and 6% (100% sesame meal, 50% sesame meal and 50% soy meal, 100% soy meal) were added to the product to replace the wheat flour and compared to the control concerning the physicochemical (pH and moisture), color and textural properties of the samples (hardness, adhesiveness, cohesiveness, springiness and shear force). Results: By assessing the physicochemical and textural properties of the samples during storage period, the amount of pH, hardness and shear force increased and moisture content and cohesiveness, L*, a* and b* of the samples decreased and no significant change was observed in the springiness of the samples. Increasing the amount of substitution in the samples caused increases in L* of the samples and shear force and reduced the amount of pH, hardness, springiness, cohesiveness and a* of the samples. On the other hand, by increasing the ratio of sesame meal, the moisture content, pH, hardness, shear force, cohesiveness, b* and a* of the samples were reduced. Conclusion: The use of sesame meal and soya in production of German sausage can produce acceptable product concerned with physicochemical and textural properties and higher nutritional value. The substitution of 3% sesame meal and 3% soy meal was introduced as the best sample.

Introduction: Dunaliella salina is a green unicellular eukaryote microalga which has no cell wall in its cell structure. In the normal condition of growth it has green color but under stress situation such as high salinity, high light intensity and nutrient deficiency. it turns to yellow. In this state, the cells produce a high amount of the second metabolite such as beta-carotene, glycerol, etc. to maintain their viability. These second metabolites have a high economic value with many applications in the food industry (natural colorant), pharmaceutical industry (pro-vitamin A) and use as additives to food and feed. Nowadays with the significant increase in the world population, it seems necessary to exploit the new alternative sources for energy and food requirement. Microalgae with their unique specifications could be an excellent choice. Materials and Methods: In this study, the optimum NaCl concentration for the growth of Dunaliella salina which was purified from Urmia Lake was investigated. Dunaliella salina cells were cultivated under 10000 lx white light intensity within modified Johnson medium. Furthermore, the amount of beta-carotene accumulated within microalgae cells due to 11 steps of 0. 5 M salt stresses was measured. Results: The optimum salt concentration related to the maximum biomass production was recorded in 1 M salinity. The highest amount of beta-carotene was 36. 64 µ g per ml of cell culture medium in 3. 5 M salt concentration. Although beta-carotene content has a descending procedure by salt addition, these amounts were considerable till 6. 5 M salinity of the culture medium. Conclusion: The culture condition can approach to the natural condition by application of salt in jection in small concentration. In this condition, a significant amount of beta-carotene can be accumulated within the Dunaliella salina cells.

Introduction: Stevia might be used as a new source of sweetener but without containing sugar and is a suitable alternative to sucrose. It is important in health care and solving restrictions of sugar consumption by diabetics. Therefore the aim of this study is to evaluate the effect of arbuscular mycorrhizal fungi and rhizobium bacteria co-symbiosis on steviol glycosides content in herbal plant of stevia. Materials and Methods: The effect of mycorrhizal fungi in three and rhizobium bacteria in five concentrations were conducted on stevia through factorial experiment in randomized complete block design with three replications in research greenhouse of the faculty of Agriculture and Food at Tarbiat Modares University. Results: The results revealed that the effect of mycorrhizal fungi, rhizobium bacteria and its interactions were significant on all characteristics. The highest percent of stevioside and rebaudioside A glycosides was gained in b0f25 and b100f50 treatments, respectively. Conclusion: It is concluded that co-symbiosis of mycorrhizal fungi and rhizobium bacteria with stevia could efficiently improve the economical yield.

Introduction: Roasting is one of the common methods of nuts processing and its purpose is to increase the total acceptability of products. The conventional roasting using hot air oven has drawbacks of low production rate, poor product quality, and high energy cost. Therefore, there is a need to develop new processing methods that can produce roasted products. The combined infrared-hot air system was explored as a new roasting method for peanut kernels. Materials and Methods: In this study the combination of infrared (IR) and hot-air was explored for roasting of peanut kernels and the effects of processing conditions including hot air temperature (100 and 120 ° C) and infrared power (130 W, 165 W and 200 W) on different characteristics of kernels (moisture content and energy consumption) were investigated. Roasting kinetics of peanut kernels were explained and compared using five mathematical models. In order to determine the coefficients of these models, non-linear regression analysis was applied. Results: According to the statistical analysis, two-term and logarithmic models showed the best fitted results. These models have acceptable R2 and adj R2 and low RMSE under all roasting conditions. Effective diffusivity coefficient of peanut kernels varied between 1. 915× 10-7-6. 054× 10-7 m2/s. The value of Deff increased by increasing temperature and IR power. The results also showed that by increasing temperature and IR power, the moisture content (%, db. ) of samples decreased and energy consumption increased. Conclusion: This study demonstrated that combination of infrared and hot-air roasting can produce high-quality roasted peanuts with lower energy cost; therefore it could be considered as a new technology for the peanut roasting industry.

Introduction: Frying is applied as one of the oldest methods of food preparation both in domestic and industrial scale. Color development during the frying process is a surface phenomenon that depends on the processing temperature and time. The aim of this research is the measurement of central temperature, surface changes and color changes the behavior of onion slices during frying process as a mathematical model at various temperatures. Materials and Methods: Onion slices with 1 cm thickness and cylindrical form were fried at the temperature of 150, 175 and 200 º C and its central temperature was recorded using K type thermocouple with 1 mm thickness by 5-second intervals. The surface temperature of the product was measured using a laser thermometer. Color parameters as brightness (L*), redness (a*), yellowness (b*) and color change intensity (Δ E) were recorded during frying time and kinetic model was fitted on their changes versus time and models coefficients were reported. Results: The temperature of the oil had a negative effect on the brightness of the fried onion and, with increasing process temperature, the brightness parameter decreased at the same time. The results of this experiment showed that most of the color changes occur in the early stages of the process. Higher temperatures increased the yellowness and redness of the onion surface from 14. 24 to 29. 31 and 5. 73 to 17. 86, respectively. Fried samples at a temperature of 200° C reduced the size about 40. 48 %. The central temperature became closer to the water boiling point at a temperature of 200° C and after a brief period at this temperature, the temperature of the center increased again with full water exhaustion. Conclusion: The kinetics of the surface color parameters changes and color change intensity (Δ E) of the onion followed the incremental exponential function and power function, respectively.

Introduction: Pomegranate tree has been originated in east Asia and Iran. The consumption of pomegranate is curative and prevents many sicknesses, therefore pomegranate has a special place in human diet. Materials and Methods: In this investigation, the effect of foliar spray application of different forms of Zinc in different concentrations on some characteristics of pomegranate fruit, has been studied. The application of spray was carried out during May and July of 2016. This study was at based on a randomized complete block design with seven treatments and three replications. Zinc sulphate fertilizer and nano-Zn chelate fertilizer were applied in 500, 1000 and 1500 mgl-1 concentrations. Results: The application of 500 mgl-1 nano-Zn chelate significantly increased fruits grains weight and fresh weight of 100 grains. 1500 mgl-1 ZnSO4 increased the pH, total acidity and ascorbic acid contents of the juice but 500 mgl-1 nano-Zn chelate had a toxic effect on all of the factors and decreased them. 1000 mgl-1 ZnSO4 significantly increased anthocyanin and EC of the juice, although 1500 mgl-1 nano-Zn chelate decreased anthocyanin and 500 mgl-1 nano-Zn chelate decreased EC. TSS and TSS/TA was increased by 500 mgl-1 ZnSO4 whereas 1500 mgl-1 nano-Zn chelate decreased both of them. Conclusion: Although different concentrations of ZnSO4 fertilizer improve the chemical characteristics of pomegranate fruit, but totally the best foliar spray application is at 500 mgl-1 nano-Zn chelate.

Introduction: Edible films can be a safe way for packaging foods such as chicken meat. The addition of plant essential oils to edible films such as chitosan can increase the shelf life chicken meat as well as the acceptability. The aim of this study is to investigate the effects of chitosan film containing Ajowan essential oils on the chemical properties of chicken fillet kept at 4° C. Materials and Methods: Chemical composition of the essential oils was determined by gas chromatography-mass spectrometer and chitosan films containing essential oils were prepared at two concentrations of 1 and 2% (v / v) by casting method. The chemical factors pH, TVN, TBA and PV in the chicken fillet samples were determined and analyzed by SPSS software, One-way ANOVA and post-test LSD were analyzed. Results: The results showed that samples packed with films containing essential oils during the study showed lower values of (p≥ 0. 05) pH, TVN, TBARs and PV in comparison with the control and non-essential oils samples and the film containing 2% of essential oils had the best effects as compared to other groups. Conclusion: The application of chitosan films, particularly with the Ajowan essential oil in chicken packaging, has a great effect on the chemical properties and increases its shelf-life.