Abstract: Three different methods: high pressure microfluidization, ultrasonic, dual enzymatic hydrolysis were employed to extract β-glucan from the cell walls of the yeast Candida utilis and the obtained extracts were designated as H-YG, U-YG and E-YG, respectively. The yields, purities, molecular mass distributions, and monosaccharide compositions of these β-glucans were compared. We also evaluated the effect of three extraction methods on the antioxidant activity and moisturizing properties of β-glucans. The results showed that the purities of β-glucan extracted by three methods were all above 96% and high pressure microfluidization gave the highest yield and purity of β-glucan of 19.6% and 97.5%, respectively. UV spectra showed that none of these β-glucans contained nucleic acids, proteins or other impurities. Monosaccharide composition analysis showed that all three β-glucans were homogenous polysaccharides composed of only glucose. The molecular mass distribution and the average molecular radius were measured by high-performance size exclusion chromatography and multi-angle laser light scattering, and the results indicated that the weight average molecular masses of H-YG, U-YG and E-YG were 1.611 ×106, 4.763 × 106 and 2.661 × 105 g/mol, the polydispersity coefficients were 1.025, 1.686 and 1.362 and the average molecular radii were 67.5, 33.3 and 43.7 nm, respectively. All three β-glucans showed DPPH radical scavenging capacity, suggesting their antioxidant potential. Furthermore, they had significant moisturizing properties in vitro, and the moisturizing effect of H-YG was better than that of glycerol in 8–24 h. All these β-glucans especially H-YG significantly contributed to promoting the generation of endogenous natural moisturizing factor. These findings demonstrated that different extraction methods affected physicochemical properties and bioactivity of yeast β-glucan, and could be applied to various fields according to their characteristics.

Key words: Candida utilis, yeast β-glucan, extraction method, antioxidant activity, moisturizing performance