High performance liquid chromatography of the hydroperoxides produced by lipoxygenases

Separation of 13-hydroperoxylinoleic acid or 13-hydroperoxylinolenic acid from linoleic acid or linolenic acid, respectively, was carried out easily and quickly by high performance liquid chromatography on porous polymer gel (TSK-Gel LS-140) using n-hexane/ethanol as an eluent. An eluent containing a large amount of n-hexane (96%) made possible the separation of 9- and 13-hydroperoxylinoleic acids. These methods were applicable for analyses of the products obtained by the incubation of soybean lipoxygenase-1 [linoleate: oxygen oxidoreductase, EC 1.13.11.12] with linoleic acid or 13-hydroperoxylinoleic acid.

Chemical composition and lipoxygenase activity in soybeans as affected by genotype and environment

Environmental and genetic influences on the chemical composition and lipoxygenase activity of 24 soybean genotypes (groups IV‐S and V) were determined. The soybeans were grown at two climatically different locations within the state of Georgia. Oil and protein contents and fatty acid composition of the oil in soybeans were affected by the environment. Five genotypes from group IV‐S has a fatty acid composition of the oil different from the other genotypes in the group. These differences appeared to be genetically controlled. The level of lipoxygenase activity in soybeans also appeared to be genetically controlled and not influenced by the environment. The study indicated that soybean genotypes could be selected for a specific climatic region based on oil fatty acid composition and lipoxygenase activity.

Soybean protein flavor components: a review

This review on the flavor components of soybean protein products examines primarily our studies on sensory evaluation of commercial flours, concentrates and isolates; on extraction of flavor components from soybean flakes with hexane‐alcohol azeotropic mixtures; on the application of proteolytic enzymes to improve flavor; and on the effect of inactivating lipoxygenase on soy beverage flavor. Evidence indicates that enzymatic reactions affect the flavor of final products. Presumably lipoxygenase is a primary culprit and linolenic acid a primary precursor when soybeans are partially processed before destroying enzymatic activity.