مجله علوم غذایی و تغذیه
سال دوازدهم شماره 1 (زمستان 1393)

Vacuum osmotic dehydration is one of the methods of preservation of fruits and vegetable. The aim of this work is the evaluation of the effects of variables in osmotic dehydration process (ambient pressure, contact time of product and solution, concentration and temperature of osmotic solution) on the quality factors of product (colour changes, texture, oil uptake) and finally achieving the optimum process conditions. A laboratory scale osmotic dehydration equipment including anaerobic jar, grid basket, vacuum pump, barometer and thermometer were used. The temperature range for osmotic solution (30 – 50° C), pressure (500-700 mbar), concentration of the osmotic solution (30- 50%) and contact time (60- 180 min) were employed. The test plans involving 31 tests were obtained by using response surface statistical models. The frying was carried out at 108ºC for 8 min and 320 mbar. The optimum conditions of 48.71ºC for the osmotic solution temperature, 92.07 mbar for the pressure, 62.92 min for the time and 34.87% for the osmotic solution concentration were obtained. By applying the mentioned optimum conditions, the colour changes, oil absorption (g/100g) dry basis and texture (N/m) were found to be, 13.63, 14.82 and 2.78 respectively. The result showed that by increasing the osmotic solution temperature, texture rigidity is decreased and colour changes is increased. Colour changes, oil absorption and texture rigidity are decreased with increased osmotic solution concentration.

Oxidation is one of the most important spoiling reaction in the oils and fats and might be delayed by the use of antioxidants to some extent. Coffee contains some effective phenolic antioxidants such as chlorogenic acids, caffeic acids ester and quinnic acids. The object of this research is to study the antioxidant activities of coffee extracts. In this research work coffee extracts were obtained by hexane and isopropanol after three hours of extraction period. The extracts yields and total phenolic compounds were determined using Folin ciocalteu method. The hexanolic and isoporopanolic extracts of both roasted and unroasted coffee from two varieties of coffee (Arabica, Robusta) were added to tallow at different concentrations. Peroxide value at 100UC (oven) and Induction period measurements at 110UC (Rancimat) were used as means to examine and investigate the antioxidant activities of the above extracts. The results indicated that coffee extracts inhibited antioxidant activities and were able to reduce the oxidation chain reaction. The highest yield of phenolic compounds, taking Gallic acid as the index was related to the extracts obtained by isopropanol and accounted for 2.17 mg/g of dry matter. This might be due to higher polarity of isopropanol as compared to hexane. Among the extracts isopropanolic extract of roasted Robusta with 15% concentration exhibited the best antioxidant activity.

Citrus fruits have different characteristics and properties consisting of physicochemical characteristics and antioxidant potential. In this study physical, quantitative and qualitative characteristic and bioactive components of four citrus varieties in the north part of Iran are studied for their possible use in the fruit juice and concentrate processing factories. Some characteristics and properties consisting of fruit length, diameter, spherical coefficient, volume, peel thickness, pulp percentage, juice percentage, TSS, sugar, TA, ascorbic acid, total phenolics and anti-oxidant capacity were determined according to the defined standard methods. The results showed that fruits were different in shape. The highest and lowest length and volume have been found in Thomson orange and Unshiu mandarin respectively. Siavaraz orange and Unshiu mandarin had the maximum and minimum spherical coefficient (0.97 and 0.91) respectively. The Thomson orange with highest peel thickness (4.82 mm) and pulp (9.53%) had the lowest percent juice extracted in the Laboratory (31.15%) and in the production line (26.78%). There was the highest amount of total sugar and TA in Unshiu mandarin (9.19 g.g-100) and Siavaraz orange (1.85 g.g-100) respectively. Considering the bioactive compounds, the results revealed that there was the highest concentration of ascorbic acid and total phenolic compounds in Siavaraz orange (58.3 mg.g-100) and moro Blood orange (55.25mg.g-100) respectively. Furthermore, there were a positive correlation between the antioxidant activity and ascorbic acid (R2= 0.91) and total phenolic compounds (R2= 0.71). The lowest antioxidant capacity was related to Unshiu mandarin with 38/19%. Thomson orange was not a suitable variety for juice production due to high peel thickness and pulp, low juice percentage and also bitter taste after juice extraction. Inversely, Siavaraz orange had more industrial indices including high juice percentage, balance pulp and the highest spherical coefficient. Unshiu mandarin and Moro (Blood orange) might be consumed as fresh or be used for industrial juice extraction.

Soya is used in meat products due to its functional and nutritional properties. Soya is also known as an intense allergen substance for some people according to the Institute of Standards and Industrial Research of Iran, therefore its presence must be mentioned on the label of the products. The purpose of this study is to develop a PCR assay for identifying soy protein as a hidden allergen substance in meat products. In this study, soya and meat products samples were prepared. The extraction of DNA from samples were carried out according to the instruction provided by MBST kit. The specific primer pairs of soya were designed and ordered. The PCR conditions were standardized to obtain the desired amplicon of 118bp for soya. Finally the PCR products were electrophoresed in 1.5% agarose gels. This method was used for detection of soya in commercial meat products and the results were compared with their labeling statements. In optimized PCR condition, DNA fragment of 118bp for soya was amplified. This developed technique was successfully evaluated for detection of soya in meat products. The results showed that 100% of sausages and chicken nuggets, 33.3% of cold cuts, 60% of hamburgers and 75% of Loghme Kebab contained soya. The results indicated that PCR assay developed in this study was a rapid, sensitive, simple, reliable and commodious method that might be used for the detection of soya in raw and heat treated meat products.

Dates are one of the most Iran's important products and have a main role in people’s nutrition. About 35 percent of this product is converted to waste due to the improper packaging. Nanotechnology might be regarded important in packaging and storage of food by increasing the barrier properties of packaging systems and by improving their properties. In this research work due to the importance of dates, the effect of ZnO Nanoparticles and Carbon Nanotube films on sensory properties and microbial contamination of Mazafati dates are evaluated. Mazafati dates of Bam was purchased from Tehran open market. Packages were prepared from the pure Polyethylen (W) and Carbon Nanotube and ZnO nanoparticles (CZ, 0.1, 1 and 2 percent) and filled with fresh Mazafati dates and then were monitored after 90 days intervals. The results were analysed using Duncan's multiple range test. It was shown that by that the using ZnO Nanoparticles and Carbon Nanotube omposite films, the microbial load has been significantly decreased. Indeed, the number of actic acid bacteria in the samples containing carbon nanotubes and nanoparticles of zinc xide at two percent concentration, have decreased by 0.83 logarithmic cycle. The results indicated that by using nano-films, the shelf life of Mazafati dates ight be increased, without negative effects on sensory properties.

Drying is one of the oldest methods for preservation of agricultural products and it is aimed and tried to effectively increase the drying rate by heat and humidity transfer. In this study, drying process for quince fruit slices with 3, 5 and 7 mm thickness at 60–80°C to reach a maximum of diffusion effects (Deff) and decrease drying time using response surface methodology have been optimised. The results showed that Midli model had minimum amounts of RMSE, MRPD and W2 and a maximum of R2. Optimization of drying process indicated that the application of 71°C for 7mm thickness had the most diffusion effect with least drying time. Hot air drying method removes the moisture from the fruit and generally is suitable for drying quince fruit.

lowering the fat content in the products decreases the firmness of texture. In order to prevent this event gelatin might be employed to overcome this problem. But, hydrocolloid namely gelatin might affect the taste of the product. In order to solve this problem, fragrant vegetables such as Chavil might be used for this purpose. This vegetable decreases cardiovascular diseases, hypertension, diabetes, and cholesterol concentration. Moreover, it could prevent the growth of cancer cells and its metastasis. in this project, the effect of two different concentrations (0.15, 0.3 %) of gelatin on Chavil yogurt has been studied. The yogurt samples have been evaluated every seven days for 21 days in terms of pH, acidity, free fatty acid, sensory features and the rate of diacetyle formation. The results showed that gelatin causes an increase in the acidity and a decrease in pH as compared to the control sample. It also causes decreases in the production of free fatty acid and diacetyle formation. The results of sensory tests have shown that gelatin does not have negative effect on the sensory features of the product. The present study indicated that by applying gelatin together with Chavil better quality yoghurt is produced.

Some of the post-harvest agricultural crops due to the improper maintenance of products, as well as damages caused by the pests might lose their quality. Therefore, the use of chemical compounds to increase the shelf life of fruits and vegetables might be inevitable. The aim of this research is to evaluate the effect of ozone, acetic acid and menthol on the shelf life and keeping quality of early Urbana Y tomato after harvesting. Tomato (Early Urbana Y variety) were subjected to different treatments such as ozonated water (0.2 ppm), acetic acid (0 and 4% V/V), menthol (0, 250 and 500 ppm) and combination solutions. Necessary experiments concerned with weight wasted, brix, sugar content, acidity, ascorbic acid content and microbial tests were carried out on the samples and the control. After 15 days of preservation in the environmental temperature, experiments were repeated and the influence of the treatments on the samples were determined and compared to the control. The results indicated that the treatment caused the reducing sugar, waste and the microbial counts to be less than control after the keeping period, while the titratable acidity and ascorbic acid content in tomatoes were preserved better. Treatments affected the quality of tomatoes and the combined treatment; ozone, acetic acid and methanol at 500 ppm exhibited better effect.

Olive oil is a valuable and popular oil among the oils consumed and the demand for its production and consumption is increasing continuously. Therefore, the purpose of this study is to evaluate the effect of refining operation on the physico-chemical characteristics of virgin and refined olive oils. Two olive cultivars (Bladi and Arbequina) were collected from Fadak Farm (Iran – Qom region). The oils were extracted, bleached and deodorised using two different conditions. The first batch was bleached and deodorized at 50 for 30 minutes and the second batch was bleached at 70 and deodorized at 135 for 45 minutes. Tests concerned with the determination of fatty acid composition, free fatty acid content, peroxide value, conjugated dienes and trienes, total poly phenols, colour and induction periods were carried out on the oils. The results indicated that moisture, oil content of whole fruit, kernel and pulp were significantly different. Fatty acid compositions were not affected after the two treatment methods with the exception of Bladi variety that slight changes concerned with saturated and unsaturated acids occurred. The total polyphenols in Bladi and Arbequina varieties in the first treatment were 51.87% and 34.92% and in the second treatment were 68.67% and 92.67%, respectively. Conjugated dienes and trienes for each sample after the treatment decreased and increased respectively and the change after the second treatment was higher. The application of higher temperature for longer period affected both oils qualitatively. However the changes in acidity and peroxide values were similar.

Nowadays the application of natural dyes in food and pharmaceutical products are desirable and might be important. Phycociyanin is a natural pigment with powerful antioxidant activity and is extracted from the Spirulina algae. Due to the possible toxic effects of some synthetic colors and antioxidants the use of natural additives in food and pharmaceutical product are perfected. In this research, phycocyanin is produced at 30 and 35, using glucose, ethanol and acetic acid as carbon source in both batch and semi continues methods with variable light intensitives of 2 and 3.5 Klx for maximum production. The experiments were carried out according to Full Factorial method using fixed and variable conditions on the samples. The results show that in batch and semi continues methods with 1.0 mlL-1 carbon source and 2.0 Klx light intensity by increasing the temperature from 30 to 35, the production of plycociyanin in glucose as compared to the other two carbon sources have rapidly declined. The results also indicated that by using a concentration of 1 mlL-1 carbon source and light intensity of 3.5 Klx at 30, there were not significant differences between the batch and semi continuous methods. It was concluded that the amount of production by using glucose was maximum and also using ethanol showed good yields with minimal differences.