Frying performance of soybean oils with reduced linolenate content and methods to monitor deteriorative changes
The performance during frying of three expeller-pressed physically refined soybean oils with different contents of linolenic acid (ULL, 1.5%; LL, 2.6%; control, 5.2%) was tested. French fries were fried in a commercial-like setting for 6 hr/day during 23 consecutive days. There were no significant differences in color or in polar material content. The amount of conjugated dienoic acids was higher in the control than in both ULL and LL oils throughout the frying process. Free fatty acid levels were not different among the oils until day 14, after which ULL was higher than the control for the remainder of frying. There were no differences in painty, buttery, and potato flavors, but the control had higher sensory scores for rancid flavor. NIR spectroscopy calibrations were developed to determine free fatty acids, conjugated dienes and total polar materials as methods to reduce time and chemical waste in frying oil quality determinations.