فصلنامه پژوهش های صنایع غذایی
سال بیست و دوم شماره 2 (تابستان 1391)

Castor plant (Ricinus communis L.) is one of the most important medicinal plants which are used in pharmaceutical, cosmetics and hygienic industries of many developed countries. The versatile application of castor oil in different industry and recently in food industry has led to much research being done on castor oil. The purpose of this research was to determine the effect of climatic factors on oil content, physicochemical properties and fatty acid composition of medicinal castor oil in Azarbaijan region to add on performance of this valuable medicinal plant. Oil extraction yield in the analysed samples were 35-51%. The results on other physicochemical properties were as follow refractive index (1.404-1.421), chlorophyll content (0.16-0.39 mg pheophytin/kg Oil), acid value (0.29-0.6 mg NaOH/g Oil), peroxide value (below 1), saponification value (167-178 mg KOH/g Oil) and iodine value (75-85 g I2/100 g Oil). In this research, fatty acids of extracted oils were determined by GC. Among determined fatty acids, ricinoleic acid (85.7-88.9%) had the highest level, followed by oleic acid (3.9-4.2%) and linoleic acid (2.2-4.1%) which was related to differences of region climatic factors. The results revealed that climatic factors can be effective on the oil content, physicochemical properties and fatty acid composition of castor oil.

Iranian locust bean gum (LBG) was extracted and used in the formulation of ketchup sauce and its effects on different properties of the produced sauces were evaluated. Four different formulations were produced, control was without any gum, and the other three samples were produced with Iranian LBG, commercial LBG or tragacanth gum and their functional properties were compared in terms of rheological properties, consistency, syneresis and color. The results showed that Iranian LBG improved rheological properties and consistency and reduced the syneresis of the ketchup samples compared to the control without gum. In some cases the Iranian LBG acted better than the commercial LBG and therefore more research is recommended for improving its functional properties and using of it in food materials.

In this study, isolation and identification of bacteriocin producing strains from west Azerbaijan Kuppeh cheese is investigated. For this purpose, 8 samples of cheese were collected from different parts of west Azerbaijan. 36 out of 48 colonies of isolated Lactic Acid Bacteria (LAB) showed high antimicrobial activity against the indicator strains. In order to avoid of antimicrobial effect of organic acid produced by LAB, in this step, the pH levels of supernatant were adjusted to 6.5-7. After pH adjustment, only 12 isolated strains showed antimicrobial activity. A comparative study using morphological and biochemical tests demonstrated that 2 isolated strains were belonging to Lactobacillus plantarum, 1 belonging to Lactobacillus brevis and 1 belonging to Lactobacillus paracasei. The result of partial purification and electrophoresis of bacteriocin indicated that the molecular weight of proteins were 15, 40 and 50 kDa.

One of the most important problems in date processing is unsuitable storage conditions and packaging type. In this research date fruits (Kabkab variety) were packed within aerobic atmosphere and vacuumed PA/PE pouches and stored at different temperatures (-20, 4, 25 and 40 ºC). The samples were evaluated for different chemical parameters (moisture content, total soluble solids, titratable acidity and pH) monthly during the storage period up to 6 months. The storage temperatures and time greatly (P< 0.01) affected all chemical parameters tested in date fruits during storage. Packaging type had a significant effect (P< 0.01) on total soluble solids, titratable acidity and pH of dates, but did not affect moisture content. A significant decrease of moisture content was detected for all samples throughout the storage period. However, it was noted that moisture decreasing rate was significantly greater at 40 ºC compared to other storage temperatures. The titratable acidity of vacuum packed dates stored at -20 ºC and 4 ºC was lower than the other samples. A significant increase of total soluble solids was observed for all samples during storage.

In this study, beta-glucan from hull-less barely was used to decrease fat level of mayonnaise at levels of 20, 30, 40, 50% (abbreviated names of low fat mayonnaise samples are BG20%, BG3%,BG40% and BG50% respectively) and physicochemical, textural and sensory properties of them were compared with control sample containing 75% fat (FF). The results showed all of low fat samples had lower energy content and higher moisture compared control sample. Results of textural and sensory experiments of low fat mayonnaise revealed that increasing level of fat replacement with beta-glucan from 20 to 50% decreased viscosity and altered textural properties so that with increase replacement percent and reduction of fat, the lowest and highest viscosity belonged to BG20% and BG30%, respectively. In term of textural properties the highest firmness and adhesiveness belonged to BG20%. In sensory evaluation the highest preference was observed in BG30% and BG50% that reveal the possibility of using beta-glucan as fat replacement in mayonnaise formulation successfully.

In this study, reduction of sugar content in quince jam using stevia sweetener was evaluated. In order to optimize the formula and low-calorie quince jam production, three factors of pectin, stevioside and sugar content at three levels were evaluated using response surface methodology (RSM) with design of D-Optimal. To evaluate the model and determine optimum points, the response of consistency was used. The effect of sugar and pectin on consistency was in quadratic and linear manner, respectively and also had an interactive effect on the consistency. According to the results, there was no significant difference between actual and predicted consistency and the optimized condition for jam production was 0.4% pectin, 0.27% stevioside and 50% sugar. The results showed that the production of low-calorie jam using stevioside by reducing the sugar content to 50% without any changes in its sensory properties was possible.

The effect of three types of stabilizers including carrageenan, pectin and commercial stabilizer CHO 400 at the levels of 0 (as control), 0.01, 0.05 and 0.1 percent (w/w) on the stability, rheological and sensory properties of chocolate milks was studied during 15 days of storage at 4 °C. The analysis of results showed that carrageenan and pectin had the most and the least effect (P<0.01) on viscosity of the samples, respectively. Any of stabilizers when used at the level of 0.01% could reduce the amount of chocolate sediment statistically (P<0.01) in comparison with control. Increasing the level of carrageenan and CHO 400 to 0.1% not only did not prevent the separation of chocolate but it also led to instability in the sample. Therefore, it is recommended to use carrageenan at the level of 0.05% to get a product with high viscosity and low sediment which is preferred by consumer.

With respect to importance of meat in the Iranian household consumption basket, the demand for all kind of meats analyzed over the 1984-2010 years, in this study. The generalized ordinary differential demand system (GODDS) utilized in order to avoid of imposing specific functional form to estimating meat demand function. Result of the functional form selection test indicates that the almost ideal demand system (AIDS) is more consistencies with real behavior of Iranian households. Finally, the AIDS used to estimating demand function of beef, mutton, chicken and fish. Result of income elasticity implies that mutton and fish are luxury goods, while beef and chicken are necessity goods among Iranian households. Values of cross-price elastisities show that the consumption of other kinds of meats is sensitive to price of mutton, while the prices of other meats have less effect on the mutton consumption.

This study was conducted to assess the effect of 1-methylcyclopropene (1-MCP) treatment on superficial scald development, α-farnesene and its oxidation products synthesis and catalase and peroxidase enzyme activities in apple fruit during storage time. For this purpose, apple fruit 'Granny Smith' were treated with 1-MCP at 1μl.L-1 (control and treated) before storage, and stored in 0.5 °C and 85±5 % RH for 24 weeks. The experiment was performed as factorial arrangement based on completely randomized design with three replication.Factors including scald severity, α-farnesene and its oxidation products concentrations and catalase and peroxidase enzyme activities were evaluated in harvest time, 6, 12 and 24 weeks during storage period. Scald development increased in control fruit during storage but treated fruits were free from scald symptoms. The amount of α-farnesene and its oxidation products in control fruit had significant difference with those in treated fruit. As in treated fruits their amounts remained lowest. Higher values of catalase and lower values of peroxidase enzyme activities were observed in treated fruits compared to control fruit during storage time. The effect of 1-MCP on scald control was more related to reduction of α-farnesene and its oxidation products concentrations than its relation to the increase in antioxidative potential of apple fruit skin.

The effect of microbial transglutaminase concentration, amount of sodium caseinate incorporation and storage time on Lactobacillus casei viability in nonfat stirred yoghurt and it`s physicochemical and sensory properties were investigated using response surface method (RSM). Enzyme concentration, amount of sodium caseinate and storage time were in the range of 0-2 Unit per gram of milk protein, 0-1.27 percent and 1-19 days, respectively. The statistical analysis of results showed that increase in enzyme concentration increased the viability of Lactobacillus casei and Lactobacillus bulgaricus viability significantly (P<0.05) and decreased the syneresis. Addition of sodium caseinate caused an increase in acidity and moisture content of samples. As well, during the storage time, pH and moisture content were decreased and acidity was significantly increased (P<0.05). According to sensory evaluation results, the higher the sodium caseinate content, the lower was the color score of treatments. As the concentration of transglutaminase increased, flavor scores for yogurt samples increased. The optimum conditions for the production of yogurt was obtained using 1.41 Unit enzyme per gram of milk protein, 0.13 percent sodium caseinate with a storage period of 15 days. Under these conditions the predicted Lactobacillus casei and Lactobacillus bulgaricus counts were 8.33 and 8.35 logarithmic cycle respectively, the percentage of syneresis was 6.72, color and overall acceptability rate were 3.37 and 3.87 out of 5, respectively.