[Effects of blanching and hydrocolloid coating of potatoes with methyl cellulose and tragacanth on French-fries oil uptake and qualitative properties]

French fries are a food product with an upward consumptuion trend in Iran. Because of high oil uptake during frying, French fries are an energy-dense food item, providing a very large number of calories to the body. Therefore, efforts to reduce the rate of oil uptake by this popular food item would contribute to the public's health. The purpose of this study was to determine the effects of blanching and coating of potatoes with methyl cellulose and tragacanth on French-fries oil uptake and qualitative properties. Strips of potato [Agria variety] were prepared, blanched in water or a calcium chloride solution [0.5%], coated with a solution of methyl cellulose [0.5, 1.0 and 1.5%], tragacanth [0.5, 1.0 and 1.5%], methyl cellulose [0.5, 1.0 and 1.5%] and sorbitol [0.5%], or tragacanth [0.5, 1.0 and 1.5%] and sorbitol [0.5%] and deep-fried. Oil uptake, moisture content, and color of the French fries were measured and their sensory properties determined and compared with those of control samples. Blanching and hydrocolloid coatings of the samples brought about a decrease in oil uptake and increases in moisture content and texture tenderness of the potato strips [p<0.01]. Blanching in calcium chloride alone reduced oil uptake by 8.61%. In comparison with the control samples, coating with methylcellulose [1.5%] with sorbitol [0.5%] decreased oil uptake from 19.85% to 16.29%. Blanching in calcium chloride resulted in a significant 5%increase in moisture content. The hydrocolloid coatings caused significant increases in moisture content and resistance to cutting of the samples [P<0.01], such that the highest moisture content [44.60%] was obsereved in the samples coated with methyl cellulose [1.5%]. Tragacanth at aconcentartion of 1.5% with sorbitol at a concentartion of 0.5% brought about the highest resistance [211/13 Newton] to cutting. The findings also showed that hydrocolloid coatings resulted in significant incremets in the L [asterisk] b [asterisk], a [asterisk] factors of the French fries color as compared to the control samples. However, there were no significant differences among samples with regard to sensory characteristic

[Functional and thermal properties of chickpea and soy-protein concentrates and isolates]

In the last few years there has been a growing trend to use chickpea as a good protein source. Chickpea protein products, such as chickpea flour, concentrate and isolate, are considered as functional food supplements, alternatives to soy protein. The objective of this study was to determine and compare the functional and thermal properties of chickpea and soy-protein concentrates and isolates. Chickpea protein concentrate and isolate were prepared from defatted chickpea flour by applying alkaline extraction and isoelectric precipitation. Chemical composition [protein, fat, ash, crude fiber, and water contents], functional properties [water and fat absorptions, gelation, foaming capacity, and foam stability], and thermal properties [glass transition and denaturation temperatures] of chickpea protein concentrate and isolate were determined and compared with those of the soy protein products. The protein contents of the concentrate and isolate obtained from defatted chickpea flour were 80% and 88.6%, respectively; the corresponding proportions for soy concentrate and isolate were 83.1% and 90.2%. There were no statistically significant differences as regards water and oil absorptions between soy and chickpea proteins. The gelation properties and foaming capacity of all the samples increased with an increase in protein concentration. However, soy protein had a higher foaming capacity and foam stability as compared to chickpea protein [P

[Effects of soy-protein isolate coating on the properties of French fries using response surface methodology]

The use of edible coatings is a suitable method to reduce oil uptake in fried foods. In this research, the effects of soy-protein isolate [SPI] coating plasticized with sorbitol on oil uptake reduction and sensory and physical properties of deep-fat fried French fries were investigated. Potato strips were coated with SPI plasticized with sorbitol at different concentrations. The effect of coating on oilp uptake reduction, water retention, crispiness and color change of French fries were determined, using response surface methodology. Moreover, the sensory acceptability of the tried potato samples was assessed. The results showed that the protein and sorbitol concentrations are the major factors affecting water retention, oil uptake reduction, crispiness, and color of the fried potato samples. Coating resulted in oil uptake reduction and water retention up to 40% +/- 2 and 80%, respectively. Nonsignificant differences in sensory characteristics of coated and uncoated samples were observed. The results showed that the models based on the response surface methodology are quite suitable for the evaluation of the effects of coating on the properties of french fries. The application of soy-protein coating reduces oil uptake, while it does not affect the sensory characteristics, of fried potato strips. It is concluded, then, that SPI coating can improve the organoleptic and nutritional properties of fried food products