Apparent Matrix Effect of Yeast Polysaccharides from S. cerevisiae on the Hydrolysis of Wine Fruity Esters

The aim of this study was to investigate the apparent matrix effect of yeast polysaccharide (YP) from S. cerevisiae on the hydrolysis of fruity ester, and to explore the potential application of yeast polysaccharide in stabilizing wine aroma profile and expand shelf life of product.

YP was extracted from S. cerevisiae by hot water extraction and alkali methods, and the basic components of YP were analyzed by ultraviolet spectrophotometer (UV), gas chromatography (GC) and high- performance liquid chromatography (HPLC). The model wine containing the conventional concentration of fruity esters was prepared and treated with YP, and the concentration of YP was set in the range of 0-2.0 g·L^-1. The effect of YP on the volatility of fruity esters was analyzed by the static headspace method. Next, the model wines with different treatments were stored at 4℃ for 6 months, and the content of fruity esters in model wine was regularly monitored. Finally, sensory analysis was used to evaluate the aroma notes of model wine stored 6-months.

Instrumental analysis showed that the total polysaccharide content of YP was (72.61±3.29)%, and the protein contents accounts for (11.20±0.02)%. The main monosaccharide composition of YP was mannose and glucose, and their molar ratio was 1.790:1. The high molecular weight components of YP are 18, 163 and 21 819 kD, and the low molecular weight components are 576 Da. Static headspace analysis indicated that YP treatment could reduce the volatility of acetate esters in model wine, especially 0.8 g∙L^-1. While YP treatment could increase the volatility of ethyl esters. Data of regular sampling found that the hydrolysis rate of ethyl esters was significantly higher than that of acetate esters during 6 months storage. Compared with the control, 0.4-0.8 g∙L^-1 YP slowed down the hydrolysis of acetate esters and ethyl esters by 10%-40% and 3.7%-26.7%, respectively. Sensory analysis showed that model wine added with YP showed higher MF% of temperate sour and sweet fruity, and preserved fruit and floral aroma notes of wine samples compared with the control.

From the study of model wine system, it was concluded that adding 0.4-0.8 g∙L^-1 YP during wine storage slowed down the hydrolysis of fruity esters, stabilized wine fruity aroma profile, and showed potential application value for prolonging wine shelf life.