ARS | Publication request: Frying Quality and Stability of Low and Ultra Low Linolenic Acid Soybean Oils

Submitted to: Journal of American Chemists Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 2002
Publication Date: March 20, 2003
Citation: WARNER, K.A., GUPTA, M. FRYING QUALITY AND STABILITY OF LOW AND ULTRA LOW LINOLENIC ACID SOYBEAN OILS. JOURNAL OF AMERICAN CHEMISTS SOCIETY. 2002. v. 80. p. 275-280.

Interpretive Summary: Oil-containing foods that consumers buy need to be able to stay on the supermarket shelves for long periods of time. Some foods with certain types of oil or fat do not have long shelf lives and can become rancid and unacceptable to consumers. In order to improve the shelf life of foods, we have investigated new ways to keep packaged fried food from becoming rancid. One method is to use oils that have compositions that help prevent rancidity. For example, if an oil has less of what is known as polyunsaturated fatty acids, then the oil may be less likely to become rancid quickly. In this study, we investigated the amount of a polyunsaturated fatty acid called linolenic acid that a soybean oil should have in order to keep fried food from becoming rancid. We found that if the amount of linolenic acid was 0.8%, that the fried food was better quality than if the linolenic acid content was higher at 2%. Results of this research will guide both plant breeders and users of vegetable frying oils in the production of oils with optimum fatty acid compositions to achieve good quality, healthful fried foods and will benefit both consumers and food manufacturers.

Technical Abstract: To determine effects of very low levels of linolenic acid on frying stabilities of soybean oils, tests were conducted with 2% (low) linolenic acid soybean oil (LLSBO) and 0.8% (ultra low) linolenic acid soybean oil (ULLSBO) in comparison with cottonseed oil (CSO). Potato chips were fried in the oils for a total of 25 hours. No significant differences were found for either total polar compounds or free fatty acids (FFA) between samples of LLSBO and ULLSBO; however, CSO had significantly higher percent polar compounds and FFA than the soybean oils at all sampling times. Flavor evaluations of fresh and ages (1, 3, 5 and 7 wk at 25 deg.C) potato chips showed some differences between potato chips fried in different oil types. Sensory panel judges reported that potato chips fried in ULLSBO and ages for 3 or 7 wk at 25 deg.C had significantly lower intensities of fishy flavor than did potato chips fried in LLSBO. Potato chips fried in 5 hr ULLSBO and ages 7 wk at 25 deg.C had significantly better quality than did potato chips fried in 5 hr LLSBO and aged under the same conditions. Hexanal was significantly higher in the 5 hr LLSBO sample than in potato chips fried in 5 hr ULLSBO. The decrease in linolenic acid from 2% to 0.8% in the oils improved flavor quality and oxidative stability of some of the potato chip samples.