IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2009 | Volume:6 | Issue:1|Papers Count:11

Due to the environmental hazards of using plastic films, studies on the development of plant based films such as soy protein films, are receiving more attention. In this research, edible films were prepared from soy protein isolate and the effect of glycerol as a plasticizer at three concentration levels of 0.4, 0.6 and 0.8 g/g of soy protein isolate on the properties of these films was investigated. Some Mechanical properties, i.e. tensile strength and extension, and physical properties, i.e. water vapor transmission rate, opacity, water adsorption and solubility were examined. Films prepared without glycerol were very brittle and could not be examined. Results showed that increasing the concentration of glycerol led to a significant (p<0.05) increase in extension rate and decrease in tensile strength of soy protein isolate films. Solubility percentage, water adsorption and water vapor transmission rate of the films were found to increase when the glycerol level increased. Although glycerol addition reduced the opacity of the films, its concentration did not have a significant correlation with this parameter (p<0.05).

The goal of this research was comparing physicochemical stability of non alcoholic carbonated beverages contained high fructose corn Syrup and sucrose during storage.Soft drinks were made with three formulations of lemon , cola and orange soft drinks and in their formulations ,sucrose was replaced with 60%, 80% and 100% of HFCS (55%) and were stored at 4oC, 25oC and 40oC for one , two and four months. Samples were analysed for titrable acidity, pH, density, brix and color stability.pH, brix and density decreased although titrable acidity increased during storage. There was no significant difference between samples contained HFCS and sucrose (P>0.05).Results showed that color of samples were stable at different temperatures (4oC, 25oC and 40oC) of storage up to four months (P<0.05) but exposing to sun light made Carmoisine unstable and HFCS intensified this effect.

Bread fortification with natural fiber sources (e.g. rice bran) would be the best suitable way to replace nutrient and cause improving quality characteristics. In order to determine the effect of rice bran (in four levels 0, 3, 6 and 9%) on dough rheological and bread textural properties of two types of wheat flour (with 82% and 88% extraction rate) a completely randomized experiment with factorial arrangement and 3 replications was conducted. textural properties of bread (Hardness, Extensibility and Toughness) were determined after 2, 24, 48 and 72 hours of storage. Also organoleptic properties of baked products were compared with control samples. Results showed that addition of rice bran reduced the firmness and toughness of bread during a storage period of 3 days. The rheological behavior of dough containing rice bran was studied using farinograph. Water absorption, stability, dough development time and valorimeteric value were increased and mixing tolerance index was decreased by addition of rice bran in flour with 82% extraction. Increasing the level of rice bran, in flour with 88% extraction, caused decrease on dough valorimeteric value, mixing tolerance index and stability. Sensory evaluation showed that the best treatment for Barbary bread production is combination of 6% rice bran in flour with 82% extraction rate.

Appropriate harvesting time of fruits and vegetables is one of the most important quality factors for many purposes such as storage, processing and fresh markets. For determination of maturity index and the best harvesting time of main fruits in Qoochan region the samples of Golden and Red Delicious apples, domestic varieties of cherry and sour cherry and Thompson seedless grape were harvested daily from one week before and after conventional harvesting time. Texture for apple varieties and other factors such as the total soluble solids, acidity, maturity index (TSS/acidity) and energy units were determined each day for all sample fruits. The data were statistically analyzed and the results showed that the best harvesting time for Thomson seedless grape, Golden and Red delicious apples are 2, 14, 15 October respectively, 24 May for cherry and 21 June for sour cherry are recommended. However the climate is very effective factor on date of harvesting and maturity of fruits.

The colour of black cherry preserves is an important parameter affecting the visual quality and overall acceptance of consumers. That is considered to be highly correlated to the packaging materials. In this study, two containers namely TP can and flexible pouch were used for black cherry preserves. The flexible pouch had three layers: polyethylene (100m), aluminum foil (9m) and polyester (12m). Other variables were temperature in 4 levels, (4, 23, 35 and 40oc) and time in 4 levels, (0, 30, 60 and 90 days) after production of samples. Colour changes were determined by using a spectrophotometer at 515 nm. The statistical analysis indicated that samples in flexible pouch had higher absorbance and better colour than samples in TP cans (p<0.05). Temperature had statistically significant effect on the absorbance of the samples. Linear model for black cherry was developed and presented to predict colour changes at different temperature. Further, absorbance of samples increased with time until about 60 storage days and then tended to decrease slowly.

Bread can be referred to as an unstable material, and bread staling as a multifaceted process involving physical, chemical, and sensory changes that are related together. Bread staling has been the subject of a number of studies to obtain an understanding of its intrinsic mechanism and thereby to modify dough recipes and increase shelf life. Because of the complexity of the process, most researches address specific bread properties during its shelf life. An overall description of the staling process remains to be evaluated. Bread staling is characterized by many physical and chemical phenomena such as changes in texture, water migration, starch crystallization, and component interactions. Analyses of bread staling have evolved over time, as instrumental technology and knowledge of the subject have progressed. Various analytical techniques are available for monitoring changes at macroscopic, microscopic, and molecular levels. Careful selection of techniques offers a strategy to investigate the bread staling mechanism. Frequently experimental approaches attributes of stale bread have involved x-ray diffraction, differential scanning calorimetry (DSC), rheological, chemical, sensory and molcular investigations. The combination of various techniques can be a powerful approach to the study of physiochemical changes of complex phenomena. Choosing an appropriate method becomes a significant factor in interpretation of results in time-dependent processes. Scientists need to approach this complex problem with well-planned strategies so experimental data can serve as a fundamental understanding of molecular structure and function relationships in bread.

The flat breads (Sangak, Barbari) have got great importances Iranian diet. The quality of these breads is very important from consumer point of view and the inferior quality would cause the bread loss in the country. The aim of this research was to study the effect of the freezing, freeze storage and freeze thaw on the quality of two flat breads. For this Sangak and Barbari were baked and packed on polyethylene bags and stored at -80oC in household freezer. The breads were taken out after periods of one, two, and three weeks from the freezer and thawed at room temperature and heat condition (80oC). The textural properties of the frozen breads were determined in DSC and TPA apartuses, and the sensory tests were done with scoring method by trained panels. The results of the DSC study showed that in the periods of 1, 2 and 3 weeks the retrogradation stopped on these breads and the amount of starch retrogradation in thawed breads (at room temperature and heat condition) did not show significant differences (P<0.001). The results from the TPA showed that the amount of force needed to make slices of the breads were significantly different (P<0.001). The results of sensory test in the case of thawed bread under heat condition had acceptable quality. From the result of this research it can conclude that the freezing can be used for preservation of these breads and thawing of them should be done under heat condition.

In this research, the effects of three variables, soymilk concentration (0-25%), CaCl2 (0.3-1%) and coagulation temperature (30- 40oC) on sensory (taste, texture) and chemical (amount of total solids, protein and fat) properties of UF Feta cheese made from cow's milk and soymilk blend were investigated. The central composite experimental design (CCD) was used and the data were analyzed using response surface methodology (RSM). Coefficients of determination, R2, of fitted regression models for taste, texture, total solids, protein content and fat content were 0.965, 0.918, 0.924, 0.999 and 0.841, respectively. The Result of analysis of variance (ANOVA) table showed that lack of fit was not significant for all response surface models at 95%. Therefore, the models for all response variables were highly adequate. The results showed that the optimum processing conditions for producing cheese with highest overall values for response variables were 15% soymilk, 0.3% CaCl2 and coagulation temperature of 38oC. The response values for such product are: taste 3.9, texture: 4.72, total solids: 35.13%, protein: 13.45 %and fat: 14.05%.

This study was performed to determine proximate composition and fatty acids in muscle of common carp and grass carp that are commonly consumed in Iran. There is no significant difference in the content of protein, lipid and ash samples of in these two fish species (p>0.05). Grass carp had significantly higher moisture contents than common carp. The fatty acid composition of common carp and grass carp were found to be 32.86 and 34.06% saturated (SFA), 39.43 and 25.02% monounsaturated (MUFAs) and 24.13 and 37.54% polyunsaturated fatty acids (PUFAs), respectively. In both fish, palmitic acid C16:0 and oleic C18:1 n-9 acid were the principal saturated and monounsaturated fatty acids, respectively. The dominant poly unsaturated fatty acid (PUFA) was Docosahexaenoic acid (C22: 6n-3) in grass carp and Linoleic acid (C18: 2n-6) in common carp. The content of n3 PUFAs was 8.6% for common carp and 25.3% for grass carp. Arachidonic acid (20:4n6) content was 2.55% in grass carp and 1.33% in common carp. Muscle fatty acid composition of common and grass carp showed that there are significant difference in among all the fatty acids except for 22:0 and SFA (p<0.05).

In order to increase the heat efficiency of solar driers a shelf type solar dryer with two collectors was designed and constructed in Agriculture Research Center of West Azarbaijan, and used to dry tomatoes slices. This experiment was conducted by complete randomized factorial experimental design in 2 factors and 4 replicates. The first factor was pretreatment in 3 levels, without pretreatment (control), dipping in boiling water for 15 second and dipping in 2.5% boiling brine for 10 seconds and second factor was drying method in two levels, open sun drying and shelf type solar dryer. The analysis of the results showed that average temperature of inside of the solar dryer in first and second years were 9.5 and 12 higher than the average ambient temperature respectively. The results also showed that in the first year the moisture contents of dried tomatoes produced using solar dryer was about 25% the lower than that produced by open sun drying, while in second year moisture contents were not significantly different. Also blanched slices in 2.5% boiling brine had little damage, more rehydration ratio and better color in comparasion with other treatments. The percentage of damage and contamination of the sliced produced using solar dryer was reduced by 40% in comparison with. The samples dried in open air. Therefore according to the results obtained, it is recommended to blanch slices with 2.5% boiling brine solution for 10 seconds to get better results.