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Saccharification, fermentation, and protein recovery from low‐temperature AFEX‐treated coastal bermudagrass
Author(s) -
Holtzapple Mark T.,
Ripley E. Payson,
Nikolaou Michael
Publication year - 1994
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260440914
Subject(s) - cellulase , trichoderma reesei , chemistry , pectinase , hydrolysis , sugar , cellulose , fermentation , food science , reducing sugar , biochemistry , enzyme
Abstract Coastal bermudagrass was pretreated by a low‐temperature ammonia fiber explosion (AFEX) process, which soaked the grass in liquid ammonia and then explosively released the pressure. Saccharifying enzymes were systematically applied to the AFEX‐treated grass corresponding to low, medium, and high loadings of cellulase/hemicellulase (from Trichoderma reesei ), cellobiase, glucoamylase, and pectinase. Three‐day sugar yields linearly correlated with the logarithm of the cellulase loading. Supplemental enzymes (cellobiase, pectinase) caused upward shifts in the lines. The linearity and upward shifts are consistent with the HCH‐1 model of cellulose hydrolysis. The hydrolysis sugars were converted to ethanol using yeast ( Saccharomyces cerevisiae ). The solid residues were treated with proteases to attempt recovery of valuable proteins. The low‐temperature AFEX pretreatment was able o nearly double sugar yields. At the highest cellulase loadings (30 IU/g), the best reducing sugar and ethanol yields were 53% and 44% of the maximum potential, respectively. Protein recovery was, at most, 59% © 1994 John Wiley & Sons, Inc.