Effects of frying oil type on its stability and composition of fried food

The stability of three frying oils (rapeseed, sunflower, and rice) and their effect on the nutritional value of deep-fried fish fingers (FF) and potato croquettes (PC) was evaluated, considering the nutritional importance of reducing the amount of oil absorbed by fried foods. Ten frying cycles were performed for each food to mimic the repeated frying conditions. Dry matter content of fried foods was determined gravimetrically; fat extraction was performed using a Soxhlet apparatus. Oil stability changes were evaluated using the Schaal test; colour changes were monitored spectrophotometrically. Repeated frying had no significant effect (P > 0.05) on the fat content of the tested foods but influenced the dry matter content of PC. The highest and lowest oxidative stabilities during repeated frying were observed for rice and sunflower oil, respectively. During the frying of FF, all oils tended to darken after each frying, which was not observed for PC. The intake of fat owing to the consumption of one portion of the fried FF (150 g) or PC (200 g) approximately equals 9 g and 5 g, respectively. This demonstrates that fried foods themselves (not only the oil soaked) could be a considerable source of fat.