Improving cellulose attribution by selectively removing yeast glucans from grain fermentation intermediates

Abstract

This article presents an industry-relevant method for quantifying cellulose in mixed substrate samples. Addressing possible cellulose loss under cold caustic conditions in previous cellulosic glucan measurements, we employed dimethyl sulfoxide (DMSO) as an alternative solvent. This avoids possible mercerization reactions but may leave some resistant starch in the sample. Utilizing an enzyme mixture including pullulanase to remove the resistant starch simultaneously selectively removing yeast β-glucan using a commercially available Zymolyase. Our analytical procedure demonstrated excellent reproducibility, with coefficients of variance of 7.14% or less, when measuring cellulose in low cellulose content samples. The method was tested on relevant lab and plant samples, showing an average 0.9% ethanol derived from the conversion of cellulose when cellulase was added to the process and zero response when no cellulase was added. These findings indicate that a cellulose method using DMSO, pullulanase, and the commercially available Zymolyase provides a complete and accurate view of cellulose content, composition, and conversion in industrial fermentation processes.