Effect of enzyme selection and process parameters on yeast β-glucan solubilisation efficiency and molecular weight

Abstract

Soluble yeast β-glucans are widely used in food, feed, pharmaceutical, and biotechnological applications. Their production commonly relies on acid hydrolysis or chemical derivatisation, processes that offer limited control, generate substantial chemical waste, and may compromise β-glucan functionality by introducing new functional groups on sugar moieties. In this work, we investigate an enzymatic approach for the controlled solubilisation of native, insoluble yeast β-glucan to lower-molecular-weight fragments. The impact of enzyme selection and processing parameters (pH, temperature, time) on solubilisation efficiency and molecular structure of the solubilised product was evaluated. Within 24 h, 9 to 95% of the insoluble yeast β-glucan stream was solubilised, depending on the enzyme preparation used. Specific enzyme preparations exhibited pronounced exo-enzymatic side activity, leading to hydrolysis of up to 70% of the solubilised material to glucose, thus resulting in substantial product loss. By selecting appropriate enzyme preparations and processing conditions, soluble β-glucan fractions with various apparent molecular weight distributions (3-300 kDa) and high diversity in molecular weight were obtained. Overall, an enzymatic approach provides a more sustainable and controllable alternative to acid hydrolysis, enabling the production of soluble β-glucan without chemical modification and the associated introduction of new functional groups.