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

ABSTRACT

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