(639a) Enhancement of Enzymatic Digestibility of Microcrystalline Cellulose by Treatment in Subcritical Water

Microcrystalline cellulose was treated with sub-critical water in a continuous flow reactor for enhancing its enzymatic reactivity with cellulase enzyme. Cellulose-water slurries were mixed with preheated water at a mixing junction and rapidly heated to the reaction temperature. The reaction product was immediately cooled to the ambient temperature using a heat exchanger. The resulting cellulose was characterized for its crystallinity and enzymatic hydrolyzability. Experiments were conducted at temperatures ranging from 200 to 315 °C, at 27.6 MPa, and reaction times of between 3.4 and 6.2 s in a continuous flow apparatus.

The samples were examined by degree of polymerization test, XRD, FTIR, and SEM analyses for assessing any transformation in the cellulose structure. The findings show that the degree of polymerization of cellulose treated at 315°C is decreased substantially, which helped in the enhancement of its enzymatic digestibility. SEM pictures of such samples show the development of cracks on the cellulose surface thus increasing the accessibility of enzymes. Nearly three folds increase in enzyme reactivity is observed after one hour of treatment with cellulase enzyme at loading of 3.5 FPU/g glucan, for cellulose samples treated at 315°C in sub-critical water. However, XRD and FTIR analysis results did not show any decrease in crystallinity index for all the samples.