| Abstract: | Refined, bleached, and deodorized soybean oil and vanaspati (partially hydrogenated vegetable oil blend consisting of peanut,
cottonseed, nigerseed, palm, rapeseed, mustard, rice bran, soybean, sunflower, corn, safflower, sesame oil, etc., in varying
proportions) were used for deep-fat frying potato chips at 170, 180, and 190°C. Refractive index, specific gravity, color,
viscosity, saponification value, and free fatty acids of soybean oil increased with frying temperature, whereas the iodine
value decreased. The same trend was observed in vanaspati, but less markedly than in soybean oil, indicating a lesser degree
of deterioration. Iodine values of soybean oil and vanaspati decreased from their initial values of 129.8 and 74.7 to 96.2
and 59.6, respectively, after 70 h of frying. Polyunsaturated fatty acids decreased in direct proportion to frying time and
temperature. Losses were highest in soybean oil with a 79% decrease in trienoic acids and a 60% decrease in dienoic acids.
Levels of nonurea adduct-forming esters were proportional to the losses of unsaturated fatty acids. Butylated hydroxyanisole
and tertiary butylhydroquinone did not affect deterioration of soybean oil at frying temperatures. |
