Determination of oligosaccharides in soybeans by high pressure liquid chromatography using an internal standard

Abstract

Abstract A method was developed for the quantitative analysis of oligosaccharides in soybeans by high pressure liquid chromatography (HPLC). The sugars were extracted from the soy flour using an ethanol‐water solution. Separation of the oligosaccharides was effected by injecting a sample extract onto an HPLC equipped with a μBONDAPAK/carbohydrate® column. Three quantitative techniques were investigated for determining the separate sugars: (a) repetitive injection (i.e., alternately injecting equal volumes of standards and samples); (b) extract analyzed before and after spiking with raffinose (one of the unknowns); (c) the addition of a pure inexpensive internal standard, β‐cyclodextrin, which was separated completely from the other oligosaccharides. These methods were successfully applied to the quantitative analyses of two varieties of soybeans and other soybean products such as soy milk and soy protein concentrate.