Characterization of β-Glucans Isolated from Brewer’s Yeast and Dried by Different Methods

Characterization of β-Glucans Isolated from Brewer’s Yeast and Dried by Different Methods

Vesna Zechner-Krpan¹, Vlatka Petravić-Tominac¹*, Iva Gospodarić², Lana Sajli³, Senka Đaković⁴ and Jelena Filipović-Grčić⁵¹University of Zagreb, Faculty of Food Technology and Biotechnology, Department of Biochemical Engineering, Laboratory of Biochemical Engineering, Industrial Microbiology and Malt and Beer Technology, Pierottijeva 6, HR-10000 Zagreb, Croatia
²Institute for Medical Research and Occupational Health, Ksaverska cesta 2, POB 291, HR-10001 Zagreb, Croatia
³Forensic Science Centre 'Ivan Vučetić', Ilica 335, HR-10000 Zagreb, Croatia
⁴University of Zagreb, Faculty of Food Technology and Biotechnology, Department of Chemistry and Biochemistry, Laboratory of Organic Chemistry, Pierottijeva 6, HR-10000 Zagreb, Croatia
⁵University of Zagreb, Faculty of Pharmacy and Biochemistry, Department of Pharmaceutics, A. Kovačića 1, HR-10000 Zagreb, Croatia

Article history:
Received November 10, 2009
Accepted January 27, 2010

Key words:
β-glucan, β-glucan isolation, brewer’s yeast, Saccharomyces cerevisiae

Summary:
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.

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