Drying enhances immunoactivity of spent brewer's yeast cell wall β-D-glucans

Due to immunological activity, microbial cell wall polysaccharides are defined as 'biological response modifiers' (BRM). Cell walls of spent brewer's yeast also have some BRM activity. However, up to date there is no consensus on the use of spent brewer's yeast D-glucan as specific BRM in humans or animals. The aim of this paper is to demonstrate the potential of spent brewer's yeast beta-D-glucans as BRM, and drying as an efficient pretreatment to increase p-D-glucan's immunogenic activity. Our results revealed that drying does not change spent brewer's yeast biomass carbohydrate content as well as the chemical structure of purified beta-D-glucan. However, drying increased purified beta-D-glucan TNF-alpha induction activity in the murine macrophage model. We presume drying pretreatment enhances purity of extracted beta-D-glucan. This is corroborated with FT-IR analyses of the beta-D-glucan spectra. Based on our results, we suggest that dry spent brewer's yeast biomass can be used as a cheap source for high-quality beta-D-glucan extraction. Drying in combination with carboxylmethylation (CM), endows spent brewer's yeast beta-D-glucan with the immunoactivity similar or exceeding that of a well-characterized fungal BRM pleuran. (C) 2015 Elsevier B.V. All rights reserved.