Toyohide Nishibata

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.

Digestibility, Fermentability, and Energy Value of Highly Cross‐Linked Phosphate Tapioca Starch in Men

The objective of this study was to determine glycemic and breath hydrogen responses in 10 healthy men in response to highly cross-linked starch phosphate (HXLS), made of tapioca starch (TS). Plasma glucose concentration was analyzed at baseline and at 30, 60, 90, 120, 150, and 180 min postprandially. In addition, breath hydrogen excretion was measured at baseline and at hourly intervals, over 10 h, after test substance challenge. When compared with unmodified TS easily digested, the area under the curve of plasma glucose of HXLS was 64% smaller, and was almost the same as that of microcrystalline cellulose. When compared with fructo-oligosaccharide rapidly fermented by the microbial bacteria, the area under the excretion curve of breath hydrogen gas of HXLS was 93% smaller, and was almost the same as that of water only. These results show that HXLS is harder to digest and ferment than unmodified TS in men.

Evaluation of Nondigested Carbohydrates in Hydroxypropylated Tapioca Starch

In vitro and in vivo digestibilities of hydroxypropyl starch were investigated to determine an appropriate nondigested carbohydrate assaying method for hydroxypropyl starch. Hydroxypropyl tapioca starch (HPTS), with a 0.338 degree of substitution, was used as a hydroxypropyl starch source. Practically all nondigested carbohydrate in HPTS was low molecular weight and was not precipitated in 78% ethanol. The contents of nondigested carbohydrate in HPTS and in effluents of ileorectomized rats fed the HPTS diet obtained by the AOAC 2001.03 (enzyme-gravimetric-HPLC method) were almost the same, 56% and 59%, respectively. The recovery of hydroxypropyl groups from ileorectomy effluents was 98%. The AOAC 2001.03 method is suggested to be appropriate in determining the content of nondigested carbohydrates in hydroxypropyl starch.

Energy Value Evaluation of Hydrogenated Resistant Maltodextrin

Hydrogenated resistant maltodextrin (H-RMD) is a dietary fiber whose energy value has not previously been reported. We evaluated the energy value of H-RMD. We conducted an in vitro digestion test, in vivo blood glucose measurement after ingestion, in vitro fermentability test, excretion test by rats and indirect calorimetry combined with breath hydrogen measurement for humans. H-RMD was hydrolyzed in vitro in a very small amount by human salivary amylase and by the rat small intestinal mucosal enzyme. Ingestion of H-RMD did not increase the blood glucose level of human subjects. An examination of in vitro fermentability suggested that H-RMD was fermented by several enterobacteria. Oral administration of H-RMD showed a saccharide excretion ratio of 42% by rats. A combination of indirect calorimetry and breath hydrogen measurement evaluated the metabolizable energy of H-RMD as 1.1 kcal/g in humans. We concluded from these results that H-RMD was not digested or absorbed in the upper gastrointestinal tract and was fermented in the colon to produce short-chain fatty acids which provided a lower amount of energy than that of resistant maltodextrin.