Influence of cellulose structure on its digestibility in the rat.

The effect of modifying the structural properties of a purified cellulose on its subsequent digestion in the rat was determined. The three structurally unique types of cellulose used in the study were a commercial microcrystalline cellulose, a ball-milled cellulose, and an acid-swollen cellulose. The ball-milled cellulose and the acid-swollen cellulose were prepared from the microcrystalline cellulose starting material. Differences in structure between the types of cellulose were determined by X-ray diffraction measurements and by analysis of their in vitro enzymatic saccharification. The extent of fermentation of each type of cellulose within the rat intestinal tract was determined. Each of the three types of cellulose had a unique structure with respect to its measured crystallinity index and its rate of degradation in vitro by cellulase enzymes. The measured in vivo digestion coefficient for microcrystalline, ball-milled, and acid-swollen cellulose was 8.8, 12.2 and 20.3%, respectively. This represents a significant difference (P less than 0.05) in the extent of fermentation of the different structural types of cellulose within the rat intestine. The results demonstrate that modifying the structural properties of dietary cellulose can affect in vivo response.