Effect of cellulose fine structure on kinetics of its digestion by mixed ruminal microorganisms in vitro (original) (raw)

The digestion kinetics of a variety of pure celluloses were examined by using an in vitro assay employing mixed ruminal microflora and a modified detergent extraction procedure to recover residual cellulose. Digestion of all of the celluloses was described by a discontinuous first-order rate equation to yield digestion rate constants and discrete lag times. These kinetic parameters were compared with the relative crystallinity indices and estimated accessible surface areas of the celluloses. For type I celluloses having similar crystallinities and simple nonaggregating particle morphologies, the fermentation rate constants displayed a strong positive correlation (r2 = 0.978) with gross specific surface area; lag time exhibited a weaker, negative correlation (r2 = 0.930) with gross specific surface area. Crystallinity was shown to have a relatively minor effect on the digestion rate and lag time. Swelling of microcrystalline cellulose with 72 to 77% phosphoric acid yielded substrates...