نشریه پژوهش های علوم و صنایع غذایی ایران
سال هشتم شماره 2 (پیاپی 20، تابستان 1391)

In this research، the effect of different levels of carrageenan gum (0. 05– 0. 2%) and whey protein concentrate (0. 5 - 1. 5%) on physical، chemical and sensory properties of low fat mozzarella cheese have been investigated. Use of these fat replacers cause significant differences (P ≤ 0. 05) on chemical properties as increase in gum and WPC resulted moisture and protein content to increase but pH to decrease however carageenan was not affected. The physical properties of mozzarella cheese changed significantly (P ≤ 0. 05) as increase in gum and WPC resulted meltability to increase although carrageenan had largest share of this effect. Increase of carrageenan resulted free oil formation to increase but increase of WPC was not significant. Length of stretch was not affected by carrageenan although increase of WPC decreased it. Carrageenan content did not effect on color، aroma and taste but score of texture and overall acceptance increased. WPC decreased score of color، aroma and taste but texture improved. The overall acceptance of treatments that have greatest amounts of carrageenan plus moderate amounts of WPC was higher than others. Finally the review of mixture experimental design results show that best low fat mozzarella cheese will produce with composition of 0. 2% of carrageenan and up to 1% of WPC as fat replacers.

This study was carried out to evaluate the chemical compoition of Alosa Caspia and results compared with Clupeonella engrauliformis which is a common fish catch among Clupeonella and Clupeidae spp in Caspian sea. Results showed that the amount of fat، protein، ash and dry matter in Alosa was higher than Clupeonella. The fatty acid composition showed that the EPA was very high in Alosa that show this fish is rich source of omega-3 fatty acid. Then the effect of salting method on moisture and salt content Alosa Caspia were evaluated. The salting methods including traditional (common in north reigon)، brining with two salt concentration (saturated and 20% w/w brine) followed by two drying methods (sun and oven drying at 30°) were used. The texture changes during salting showed that salt absorption and water loss was different in different salting method and was higher in traditional salting method. These samples had the lowest moisture at the end of salting، but showed the highest moisture at the end of drying.

Heart disease - cardiovascular، cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study، the effect of different levels of three hydrocolloids (inulin، chitosan and xanthan) at three levels (1، 2 and 3%) on survival of Lactobacillus acidophilus، physicochemical and sensory properties of yogurt during 15 days of storage was explored using a combined design. Increased levels of inulin and chitosan positively affected La-5 count، apparent viscosity، acidity and sensory scores during storage. Using graphical method of optimizing (overlaid contour plots)، optimum ratios were: inulin 93. 4%، xanthan 0. 6% and chitosan 6%.

Enzymatic hydrolysis of Yellowfin tuna visceral protein with Neutrase has been carried out by response surface methodology using factorial design. Peptide chain length was estimated as the response surface to the hydrolysis conditions (enzyme activity، reaction temperature، and reaction time). The tuna visceral protein hydrolysate had relatively high protein (74. 56%) and low lipid content (1. 86%). R2 of 0. 85for the mathematical model indicated that 85% of the variability within the range of values studied could be explained by the model. Enzyme activity of AU/kg protein، temperature of 50°C، and hydrolysis time of min were the optimal conditions of hydrolysis. The electrophoresis pattern of the Yellow tuna hydrolysate showed no peptides size bigger than 10 KDa. The chemical score of the hydrolysate indicated that it fulfils the nutritional requirements of children with age 10-12 except Lysine and Methionine. Lysine and Methionine were the first and the second limiting amino acids، respectively and in case of children with age 2-5 lysine was predominant amino acid in the hydrolysates. It could be concluded that by application of enzymatic hydrolysis of Yellowfin tuna viscera protein، the properties of protein hydrolysate was improved.

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.

In this research green tea extract was prepared with water and then fishes in whole and gutted fish form was dipped in solutions of green tea extract (600 ppm) for 90 minutes and then were icing. During storage period (16 days)، spoilage oxidation (PV، FFA، and TBA)، spoilage microbial indices (TVB-N، TVC، PVC) and Sensory assessment with interval of 4 days were measured and compared with control treatment. Based on obtained results in all of treatments by passing time the value of all of the indexes (PV، FFA، TBA، TVB-N، TVC and PVC) increased significantly (P < 0/05). But this increase in treatments dipped in 600 ppm solution was performance slowly. Also in gutted fish form was caused higher delay in lipid oxidation and spoilage microbial relate to whole fish form. According sensory assessment results not significantly different among treatments (P > 0/05). In conclusion Obtained results showed that green tea extract with dipping gutted fish in consternation of 600 ppm was suggested for retardation of lipid oxidation and microbial spoilage in rainbow trout during storage in ice.

Analysis of food surfaces is of interest because many processes depend on their complexity. Food surfaces show several textural characteristics related to their nature، composition and processing. Food surface images and their microscopic details need to be translated into numerical data before engineering analysis. Fractal geometry is a novel concept to describe the complexity of natural shapes. In order to introduce a nondestructive method estimating the effect of process conditions on ostrich meat plates’ surface، in this research an image analysis technique was applied and the concept of fractal dimension was used to quantity the changes. Results show that fractal dimensions of the surfaces decreased with frying. Furthermore، with the increase in frying temperature، frying time and power of microwave pretreatment، a growing procedure in fractal dimension was observed. Fractal dimension as a quantity index could describe the shrinkage of deep-fried ostrich meat as a physical property.

Mayonnaise is a popular product which is consumed in large amounts. However، many consumers consider it as a unhealthy product as it contains high amounts of oil. Therefore، production of low fat mayonnaise with a quality close to that of traditional one might respond to consumer demand. In the present study، gum tragacanth was used as a fat replacer for the preparation of low fat (LF) mayonnaise. Mayonnaise samples were analyzed in terms of their rheological، textural and sensory properties. Fat was partially substituted by gum tragacanth at levels of 20%، 30%، 40% and 50%، and the samples were referred as TRF20%، TRF30%، TRF40% and TRF50%، respectively. The full fat (FF) mayonnaise (75% oil) without gum tragacanth was used as a control. Results indicated that all LF mayonnaise samples had significantly lower energy content than control، but they had higher moisture content than their FF counterpart. In terms of textural properties، the highest value for firmness and adhesiveness was observed in TRF20%. There were no significant differences between the FF and TRF50%. In terms of rheological properties، all of mayonnaise samples exhibited thixotropic shear thinning behavior. In sensory evaluation، in terms of total acceptability، the highest score belonged to TRF20%، but there was not observed significantly difference in other samples. This study showed that gum tragacanth has high potential to use as a fat replacer in mayonnaise.

In this study، symbiotic yog-ice (rozen yogurt) was produced that was inoculated with different levels of inulin (0،2. 5 amd 5%) as prebiotic compound and Lactobacillus Casei as probiotic bacteria in two types; free and encapsulated with Sodium Algint-Whey Protein Concentration for low fat yog-ice cream. The survivability of this probiotic bacteria was evaluated under simulated gastro-intestinal conditions، during 30 days storage at -18oC. In the samples with free state of probiotic bacteria، the number of viable cells، after 1h exposuring simulated gastric juice (pH=2،pepcine) decreased from 9. 78-9. 81 log cfu/ml to 6. 97-7. 26 log cfu/ml،at the end of 30 days storage at -18oC،while، the viable number of encapsulated state of probiotic bacteria، after 1h exposuring simulated gastric juice، decreased from 8. 15-8. 66 log cfu/ml to 6. 80-7. 09 log cfu/ml at the end of 30 days storage at -18oc. After exposuring simulated gastric juice، samples was ezposured 2. 5h under simulated intestinal juice (pH=7. 4،panceratin)، and the results that was gained showed that، the samples containing free probiotic bacteria after 2. 5h exposuring simulated intestinal juice decreased from 8. 808-9. 355 log cfu/ml to 5. 159-5. 9 log cfu/ml at the end of 30 days storage at -18oC. While، in the samples containing sodium alginate-whey protein concentration capsules، the viable number of cells decreased from 7. 38-8. 201 log cfu/ml to 6. 151-6. 672 log cfu/ml، at the end of 30 days storage at -18oC. The results indicate that there are significant differences (p)

Frying is an important unit operation used widely both in domestic and industrial cooking. Reduced pressure (vacuum)، microwave، deep fat and pan frying are the most important methods of food frying. Final product has good organoleptic quality (colour، texture، and flavour). The accuracy of the knowledge of mass transfer parameters (effective diffusivity coefficient، dimensionless Biot number and mass transfer coefficient) in the case of frying is essential and important for designing، modeling and process optimization. This study is undertaken to develop a more realistic approach for determining mass transfer parameters during frying of potato slices for cylindrical coordinates. These parameters were evaluated from the plots of dimensionless concentration ratios against time in sunflower liquid oil at and. Effective diffusivity coefficient، dimensionless Biot number and mass transfer coefficient ranged between to، to and to، respectively. Effective diffusivity coefficient and mass transfer coefficient were found to increase with an increase in frying temperature، whereas Biot number decreased. An Arrhenius type of relationship was found between the frying temperature and effective diffusivity coefficient.

In this study، the effect of edible coating and osmotic dehydration، as pre-treatments before drying of cucurbit، were investigated. Cucurbit samples were cut spirally and coated by carboxy methyl cellulose (CMC) 1% and ascorbic acid 0. 1% solutions and then processed by osmotic dehydration. Proportion of sample to solution was 1:10 and the solution containing sucrose %45، salt%25 and citric acid %1 (W/W) was selected as the best osmotic solution. Finally، the cucurbit samples were dried by oven (at 80 ˚C for 3 hours). The effects of CMC based coating on water loss (WL)، solid gain (SG)، immersion time، amount of salt، sucrose، citric acid absorption and color and sensory acceptability of samples were evaluated. The results showed that CMC based coating decreased SG without decreasing effect on WL which in turn decreased drying time of osmotic dehydrated samples in oven. Furthermore، the coated، osmotic dehydrated samples showed higher color quality and sensory acceptability in comparison to the control samples.

The aim of this study is extraction of phenolic compounds from walnut leaves of touyserkani variety with two extraction methods (traditional method and with microwave assisted extraction (MAE)) and evaluation of their antioxidant activity. Total Phenolic contents and antioxidant properties of aqueous، methanol (80%) and ethanol (50%) extracts in different times was determined. At the next stage، effect of methanol extract on retarding of oxidation of soy oil was assessed. All of extracts showed antioxidant activity in a concentration-dependent way. In MAE، methanol extract had highest total phenol whose content is 89. 15 ± 0. 25 mg/g. the ethanol extract presented highest activity in radical-scavenging activity (EC50 = 27. 90 µg/ml)، reducing power assay (EC50 = 93. 26 µg/ml) and antioxidant activity assay (EC50=68. 23 µg/ml). Also extract at 1000 ppm could control oxidation of soy oil and this extract was effective than all of synthesis antioxidant in retarding oil oxidation Hence we can present walnut leaves as a potential source of phenolic compounds and natural antioxidant.

During storage of eggs، unfavorable changes occur due to exertion of CO2 and water vapor from through of crust pinholes. One of the practical methods for preventing or reducing these changes is to use biopolymer-based coatings. In this research، five coating solutions based on carboxymethyl cellulose (CMC) and glycerol as plasticizer، oleic acid (1 and 2% V/V) and antimicrobial agents (potassium sorbate، natamycin and butylated hydroxyanisole) were prepared and their effects on physicochemical properties of the eggs (weight loss، pH، Haugh unit (HU) and yolk index (YI)) were evaluated at room temperature (25) during 5 weeks storage. The results showed that CMC- based coatings have considerable effects on quality of eggs and shelf life of them increased 1-3 weeks (depending on coating type). As well as، adding oleic acid to the CMC- based coating had positive significant effects (P < 0. 05) on quality parameters of eggs during 5 week storage. Adding antimicrobial compounds also caused significant difference in all parameters، except yolk index، in comparison to CMC coating without antimicrobial compounds.

The Oxidation of lipids change organoleptical properties، Nutritional value and shelf life of oils، and produce undesirable compounds that are not safe for customer”s health. There is many methods for prevention of oxidation such synthetic antioxidants، (BHA، BHT، TBHQ، GallatEster). synthetic antioxidants، have undesirable effects such cancer، motation in human body، therefore it was removed from consumption”s list gradually، and it seems necessary production of natural Antioxidants. In this research the first، plant extract included phenolic compounds، Tocopherol was extracted by methanolic solvent from kiwi peel and added at 2 concentration (400 and 80ppm) to sunflower oil without antioxidant and storage at 250c during 60 day Then oxidative stability determined by parameters such، proxid value، OSI، Acid value، Carbonyl value، Total polar compound at storage Temperature at time (0،15،45،60) days during storage and were compared with sunflower oil containing 100ppm (TBHQ). Results showed that concentration (800ppm) of kiwi peel extract was more effective than on stability of sunflower oil Related to 100ppmTBHQ، 400ppm kiwi peel extract. It seems Concentration of 800ppm peel kiwi extract to having higher levels of Phenols and tocopherols content is more effective

In this research، anti-microbial activity of ethanolic extract of licorice root against food spoilage microorganisms (Lactobacillus delbrueckii، Leuconostocmesenteroides، Candida krusei، Saccharomyces cerevisiae) in an orange flavored carbonated soft drink was investigated. The MIC and MBC of extract against Lactobacillus delbrueckii was 0. 7 mg/ml and 0. 8 mg/ml respectively، and against Leuconostoc mesenteroides MIC and MBC were 0. 9 mg/ml. Also، MIC and MBC against Candida krusei and Saccharomyces cerevisiae using microdillution method was equal to 0. 8mg/ml. In this research an orange flavored beverage preserved with natural licorice root extract was formulated and parameters such as phenolic contents، changes in population of aerobic mesophilic bacteria، yeast and acid-resistant micro-organisms during storage time were evaluated. Concentrations of 1000، 1500 and 2000 ppm of licorice root extract and samples containing 1000، 1500 and 2000 ppm of licorice root + 50% benzoate was used to control growth of food spoilage microorganisms in the beverage. Samples enriched with licorice root and a blank sample (commercial sample) were kept at room temperature and microbial counts were monitored during 1، 10، 20، 30، 40، 50، 60، 70، 80 and 90 days. Results of microbial examinations showed that the use of licorice root extract preserved the orange flavor carbonated soft drink during 90 days storage. Also، phenolic compounds showed good stability during 90 days storage time.