Determination of Dietary Fiber in Soybean

Abstract

A comparative study for determination of dietary fiber (DF) in soybean was carried out using the following methods; an enzymatic-gravimetric method for total dietary fiber (TDF) (PROSKY method), another enzymatic-gravimetric method for insoluble and soluble dietary fiber (IDF and SDF) (modified PROSKY method), and a method for fractionation into noncellulose polysaccharide, cellulose and lignin followed by analysis of their constituents (SOUTHGATE method). There was no substantial difference in TDF content among three methods. However, in PROSKY and modified PROSKY methods a part of SDF was lost during the filtlation using fritted crucibles of porosity No. 2 (40-60μm). The suitable filter was found to be porosity NO. 3.5 (16-40μm). In SOUTHGATE method, working curve using galactose as standard was superior to that using glucose for galactose content more than glucose in soybean. Roasted soybean contained less IDF and more SDF than raw soybean.