The effects of a xylanase and α β-glucanase from Trichoderma reesei on the non-starch polysaccharides of whole meal rye slurry

Abstract

The effects of extraction conditions (pH, temperature, enzymic treatment) on the extractability of rye meal non-starch polysaccharides were studied. The yield of pentosans and extractable matter increased with increases in both temperature and pH during extraction. The extract viscosity was correlated closely with the pentosan content of the extract. The molecular size of the extracted non-starch polysaccharides decreased as the extract pH decreased. Enzymic treatment during extraction increased the amount of pentosan solubilised. Xylanases almost doubled the amount of extractable pentosans, but these were degraded to oligosaccharides. With β-glucanase and protease, the pentosan content of the extract increased by 65% and 40%, respectively. In addition, the β-glucan extractability was increased with protease by 10% and with β-glucanase by 90%. Using size-exclusion HPLC it was observed that the molecular size of extractable rye β-glucans was lower than that of the extractable rye pentosans. β-Glucanase caused considerable hydrolysis of β-glucan and no more β-glucan could be detected by size-exclusion HPLC. Protease treatment decreased the molecular size of extractable β-glucan. All enzymatic treatments caused a disruption of the endosperm cell walls in the extract residue.