Characterization of β-glucans isolated from Brewer's yeast and dried by different methods

Two different procedures have been used for isolation of water-insoluble β-glucans from brewer's yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained β-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. β-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of β-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1 → 3)-β-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in β-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates. Key words: β-glucan, β-glucan isolation, brewer's yeast, Saccharomyces cerevisiae