Effect of Glucose on Fiber Digestion and Particle-Associated Carboxymethylcellulase Activity In Vitro

Abstract

Objectives of trial I were to delineate effects of glucose addition on digestion of cellulosic and hemicellulosic fiber sources in vitro as either pH-dependent or pH-independent.Two buffer media (regular and strong), three fiber sources (cellulose, soyhulls, and corn bran), and four glucose concentrations (0, 10, 25, and 50 mM) were used in an in vitro digestion system in a 2 x 3 x 4 factorial arrangement of treatments.Strong, but not regular, buffer medium maintained pH >6.2 when glucose was added.Strong buffer medium and 50 mM glucose increased NDF digestion lag time.Digestion rate of cellulose was decreased when 25 or 50 mM glucose was added compared with effects of no glucose in both buffer media.Digestion rate of soyhull NDF was decreased when 25 or 50 mM glucose was added compared with no glucose in cultures containing regular, but not strong, buffer medium.Corn bran NDF digestion rate was decreased when 50 mM glucose was added with strong, but not regular, buffer medium compared with effects of no glucose.Thus, effects of glucose addition on cellulose and corn bran digestion rates were, in part, pHindependent, but effect on soyhulls was pH-dependent.Effects of adding 25 mM