Comprehensive measurement of total nondigestible carbohydrates in foods by enzymatic-gravimetric method and liquid chromatography.

Total nondigestible carbohydrate (NDC) in foods was determined by combining, not modifications, AOAC Official Methods 991.43, 2001.03, and 2002.02. Total NDC included insoluble dietary fiber (IDF) + high-molecular-weight soluble dietary fiber (HMWSDF), nondigestible oligosaccharides (NDO) not precipitated in ethanol solution, and resistant starch (RS). Eight sources of NDC (cellulose, wheat bran, gum arabic, resistant maltodextrin, polydextrose, fructooligosaccharide, galactooligosaccharides, and RS) were incorporated in different combinations into standard formula bread samples. All of the NDC sources and bread samples were analyzed for their (1) IDF + HMWSDF content with corrections for residual RS amount using AOAC Official Method 991.43, (2) NDO by liquid chromatography (LC) in AOAC Official Method 2001.03, and (3) RS by AOAC Official Method 2002.02. The correlation coefficient (R(2)) comparing calculated amounts versus measured amounts of total NDC in 11 bread samples was 0.92. Analysis of commercial food samples was also well matched with the DF + NDO value on their nutritional label. Consequently, we confirmed a single measurement of LC can determine all NDO in foods, and total NDC in foods can be determined by unifying existing AOAC Official Methods.