Fatty acid composition of oils, their oxidative, flavor and heat stabilities and the resultant quality in foods

Soybean oil (SBO) is an oxidatively unstable oil, largely because of the high concentration of linoleic acid (18:2) and linolenic acid (18:3). The unsaturated fatty acids, oleic acid (18:1), 18:2, and 18:3 in SBO oxidize in a ratio of 1:10.3:21.6. To improve oxidative and flavor stability, the SBO may be hydrogenated to reduce the concentration of PUFA (and increase the saturated FA); however, trans fatty acids (t FA) are formed and saturated fatty acids are increased during this process. There are health concerns over the consumption of a diet high in trans FAs and high in the ratio of saturated fatty acids to PUFA. Lowering the 18:3 content to a level similar to that obtained by partial hydrogenation, but without trans formation and increasing saturation has been objectives of plant breeders. A diet high in monounsaturated has been shown to help reduce health risks. Elevating 18:1 in seed oils has become more and more common.; The objectives of this study were to (1) study the effects of two low levels of 18:3 concentration (∼1.0% and 2.2%) on the oxidative and flavor stabilities of SBO and (2) determine the optimum percentage of oleic acid (OA) in six SBOs (including high-oleic SBO (79%OA), conventional SBO (control), three blended oils containing 36.9%, 50.7%, and 64.7%OA, abbreviated as 37%OA, 51%OA, and 65%OA, respectively, and a low-linolenic (LL, contained 1.4% linolenic acid) SBO, to obtain maximum frying stability while retaining good flavor potential.; In general, results of the storage study suggested that the SBO containing 1.0% 18:3 had generally significant better oxidative and flavor stability during storage at 21 and 32°C than did SBO contained 2.2% 18:3. Results of the frying study suggested that the order of oxidative stability of the six oil treatments was: 79%OA > 65%OA > 51%OA > LL ≥ 37%OA > Control, and that the order of flavor stability and eating quality of foods fried in them was: LL ≥ 79%OA > 65%OA > 51%OA > 37%OA > Control.; These findings should help soybean breeders more precisely decide compositional targets to produce SBO that have desirable properties.