IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2009 | Volume:5 | Issue:4|Papers Count:12

Soy bean is a rich source of protein and has nutritional and health benefits due to the presence of phytostrogen and its role on prevention of disease, such as cancer- gained much popularity among its consumers. These days variety of soy bean products produced in food industry, eg. Soy milk and fermented soy milk. Sensory evaluation of soy milk and soy yogurt has indicated that there is beany flavor which is objectionable to some consumers. In this study chemical, physiochemical and sensorial tests were done on samples of soy yogurt. Nine formulas of soy yogurt were prepared. The ratio of soy milk: cow milk was 70:30, 80:20 and 90:10 and gelatin added as stabilizer by the percent of 0.2, 0.4 and 0.6 were used. To achieve a higher total solid and also to improve flavor and aroma of finished product, 2.5 percent non fat dry milk and 1.5 percent whey protein concentrate were added. Viscosity, synersis, acidity, pH and sensory test of formulas were done. Viscosity increased and synersis decreased significantly with the addition of cow milk to soy milk but overall acceptability did not show any significant difference. Sensory analysis of soy yogurt indicated that fortification with 30 percent cow milk and 0.4 percent gelatin gained higher score, when compared with other formulas. To the selected formula with highest score, 5, 10 and 15 percent strawberry flavor was added. Sensory analysis of flavored soy yogurt indicates that fortification with 15 percent strawberry has significantly higher acceptability compared with other formulas.

Dairy plants are able to produce tub margarine without using special machinery of emulsion solidifying. For formation of desired texture and stable tri-glycerides crystals, Solidifying time to optimum temperature of soya hydrogenated oil crystalization must be <30 Sec. Margarine production by this method needs a continuouse ice cream maker. Fast Solidifying leads to manufacture of a surface scraper heat exchanger (SSHE) that is suitable for hardening of ice cream blend, solidify of margarine emulsion and many of other food emulsions and blends. In Also, desired butter texture may be obtained by emulsion tempering (that solidified in 3-4 minutes) at 18-22oC in overnight resting.

Rapeseeds of seven major local Iranian varieties, Option, Orient, Talaye, Global, Hyola 308, Hyola 401 and Colvert, with moisture contents of 5.49, 4.55, 5.41, 4.74, 5.53 and 5.32 (%w.b.), respectively were selected to study seed physical properties. Linear dimensions, mean diameters, sphericity, surface area, volume, true and bulk densities, porosity and static coefficient of friction of the seven varieties were measured using standard methods. Results showed that length, width, thickness, arithmetic mean diameter and geometric mean diameter of rapeseed varied from 1.838 to 2.295 mm, 1.758 to 2.147 mm, 1.591 to 1.904 mm, 1.761 to 2.104 mm and 1.76 2.095 mm, respectively. Values of sphericity, surface area, volume, true density, bulk density and porosity of rapeseed were between 0.91 to 0.957, 9.744 to 13.86 mm2, 2.667 to 6.44 mm3, 928.01 to 1370 kgm-3, 675.61 to 741.6 kgm-3, 25.3 to 45.9 %, respectively. Measurement of the coefficient of friction of rapeseeds against plywood, galvanized iron, steel, aluminum and rubber showed that static coefficient of friction varied from 0.273 on steel sheet to 0.51 against plywood. It is concluded that physical properties of rapeseeds are quite dependent on variety.

In this research the effects of kind and quantity of leavening agent on dough rheological properties and organoleptical quality of Iranian flat breads were studied. The amount of compressed yeast and active dry yeast were 1.5, 2 and 2.5 percents of the bread formula. Rheological properties of samples were studied by farinograph method, and some factors such as water absorption, dough development time and etc were measured. Sangak bread had stronger flour comparing to the other flours including Barbari and Lavash. Thus water absorption, dough development time, stability and dough strength were more than other flours, but farinograph results didn't show any change. Some changes occurred in extensograph results by addition of 1.5, 2 and 2.5 percents of compressed yeast. Sensory analysis results indicated that bread samples had better quality with addition of various contents of compressed yeast. Addition of active dry yeast decreased the quality of dough and it cause disruption of dough samples and finally decreased quality of products.

In this study, a total of 10 sample of pasteurized butter packaged by dairy industries was collected randomly from the distribution centers of these products and their chemical & microbial characteristics were analysed, based on standard methods. Fatty acid profile of all samples was also determined by Gas Chromatography. The results showed that in chemical properties 1 sample had less fat content (84%) than the standard value, 2 samples (236.4 and 236.9) had more saponification value than the standard limit and solid non fat content of 2 samples (3% and 2.6%) were more than the standard value. In microbial analysis 2 of 10 samples showed coliform (110 and 100/gram), 2 samples E.coli (2 and 3/gram) & 1 sample (333/gram) mold contamination more than the standard limit but staphylococcus aureus was not observed in any of the samples. With regard to that the imported butters were pasteurized, the microbial analysis results can indicate on the contamination of some samples during packaging or unsuitable handling and storage before packaging.

The effects of air temperature (40, 50, 60 and 70oC), air velocity (1 and 2m/s) and bed depth [1(monolayer), 3 and 5cm)] on drying time, drying rate and quality indicators of Pistachio-nuts such as peroxide value and free fatty acids was determined in an experimental air cross flow drier and optimum conditions for pistachio-nuts drying was obtained. Also effective diffusion coefficient (Deff(and activation energy were determined by using Ficks second law (between 40 to 70oC) and Arrhenius model, respectively.

In this research, the effects of storage temperature and relative humidity were studied on quality factors of pistachio nuts including moisture content, peroxide value and free fatty acids. The required experiments were carried out in form of 4*4 factorial experiments in a completely randomized design (CRD) and repeated 4 times. Storage conditions were simulated in temperatures of 5, 15, 25, and 35oC, and relative humidity in range of 11 to 87%. Determination of quality factors were carried out at the startup and with 15 days intervals during storage time. Statistical analysis was done and changes of pistachio quality aspects were presented as variation intensity curves versus storage time. By using kinetic analysis of oxidation for pistachio lipids, the reaction rate of oxidation was modeled as a first order differential equation. The constants of oxidation rate in storage temperature of 5 to 35oC were in range of 0.145 to 0.567/month. By using Arrhenius relationship, Activation energy for oxidation reaction of pistachio's lipid was equal to Ea =31.459 kJ/mol.

Antibacterial and antioxidant effect of rosemary extract were investigated on vacuum packed rainbow trout (Oncorhynchus mykiss). Microbial (total viable, psycrotrophic, lactic acid bacteria and enterobacteriacea counts), chemical (pH, TMA, TBA, FFA, PV) and sensory analysis were done at 2±1oC for 18 days. Rosemary extract significantly (p<0.05) delayed lipid oxidation in treated samples. Psycrotrophic bacteria and total viable count of treated samples with rosemary extract maintained lower than the proposed acceptable limit (7 log cfu/g) as far as microbial spoilage significantly (p<0.05) decreased in rosemary samples in comparison with the control samples. According to sensory and microbial analysis rosemary samples were acceptable for eat to end of storage thus rosemary extract was able to increase shelf life of this samples 4 days in compare with the control samples.

Fruit of most persimmon cultivars are unpalatable at harvest time and it is necessary to remove the astringency by special treatments. Astringency removal treatments of persimmon in this study spray of 36% ethanol on fruits or maintaining them in CO2 enriched atmosphere, reduced soluble tannins concentration of fruits below the critical concentration that results in astringency taste (1000 ppm). According to Panel Test, the lowest astringent taste resulted from CO2 and 7.5 ml ethanol treatments. On the other hand, according to panel tester opinions there was no significant difference between astringency removal treatments on color index and desirable flesh firmness. However, astringency removed fruits had a higher quality and marketability compared to the commercial and control fruits. According to panel test, in comparison of two soluble tannins concentration assays, protein precipitation method, contrary to Folin Denis method, determined soluble tannins concentration lower than the actual amount, and therefore, protein precipitation method is not a suitable assay for determination of soluble tannins concentration in persimmon fruit.