Trans fatty acid production in deep fat frying of frozen foods with different oils and frying modalities

Frying process has been considered to be a source of trans fatty acids. However, most trans fatty acids found in foods would come from the oil used and not from the process itself To test this, the trans fatty acid production was measured frying in extra virgin olive oil (EVOO), high oleic sunflower oil (HOSO) and sunflower oil (SO) various frozen foods 20 times with frequent replenishment (FR) or without replenishment (NR) of the used oil with fresh oil during the frying. Further, the fat extracted from potatoes fried in the EVOO, HOSO and SO from the frying 8 and 20 was also analyzed by gas liquid chromatography to compare it trans fatty acid profile with that of the corresponding fryer oil. Trans fatty acids appear in lower amounts than 5 mg/g oil or fat in both FR and NR. Elaidic acid was the most abundant trans fatty acid in EVOO or in the fat extracted from EVOO fried potatoes while trims linoleic isomers were more abundant in SO. HOSO was in between. Present data suggest that frequent addition of fresh oil through the frying process minimizes the fatty acid changes contributing to obtain fried foods with less amount of trans fatty acids. The consumption of a large standard ratio (similar to 140 g) of these fried potatoes would implied the irrelevant amount of less than 0.13 g of brans fatty acids. (C) 2000 Elsevier Science Inc.