Hydration and saccharification of cellulose Iβ, II and III(I) at increasing dry solids loadings.

Crystalline cellulose Iβ (Avicel) was chemically transformed into cellulose II and III(I) producing allomorphs with similar crystallinity indices (ATR-IR and XRD derived). Saccharifications by commercial cellulases at arrayed solids loadings showed cellulose III(I) was more readily hydrolysable and less susceptible to increased dry solids levels than cellulose Iβ and II. Analysis by dynamic vapor sorption revealed cellulose II has a distinctively higher absorptive capacity than cellulose I and III(I). When equally hydrated (g water/g cellulose), low-field nuclear magnetic resonance (LF-NMR) relaxometry showed that cellulose II, on average, most constrained water while cellulase III(I) left the most free water. LF-NMR spin-spin relaxation time distribution profiles representing distinct water pools suggest cellulose III(I) had the most restricted pool and changes in water distribution during enzymatic saccharification were most dramatic with respect to cellulose III(I) compared to celluloses Iβ and II.