Ageing of Sauvignon Blanc white wines with Specific Inactivated Dry Yeasts: Effect on physical and chemical characteristics

Abstract

It is well known that polysaccharides, mainly mannoproteins, play an important role on physical, chemical and sensory quality of wines. The ageing of white wines on lees is used in order to release higher amounts of polysaccharides by the autolytic processes in order to obtain higher-quality wines. However, this technique is too slow, because the temperature and pH conditions are not the most suitable for this process. In addition, it can also involve certain disadvantages such as a greater demand on winery resources, a longer period of wine storage, the appearance of reduction notes and some microbiological alterations. Continuously, companies are looking for the development of new products from yeast, commonly known as yeast derivatives, which are rich in polysaccharides and can guarantee the improvements of the ageing on lees but minimizing its disadvantages. These products are commonly classified as inactivated dry yeast, yeast autolysates, yeast cell walls, yeast proteic extracts and purified mannoproteins as it is defined in the Enological Codex (OIV). Normally, the yeast derivatives most used during the short ageing of wines are specific inactivated dry yeast (SIDY) selected for their high content of mannoproteins. However, there is a great variety of these products which can release different contents of polysaccharides (quantity and quality) and produce different effects on the quality of wines. For these reasons, the aim of this work was to study the effect of two different SIDY on the polysaccharidic content, colour and polyphenolic compositions of Chilean Sauvignon Blanc white wines. The wines were analysed after 2 months of treatment, 3 and 6 months in bottle. Four different fractions of polysaccharides, with different molecular weight, were identified and quantified. Wines treated with both SIDY had a higher content of polysaccharides after the ageing period and during bottle storage than control wines. No differences were found between both SIDY used. No significant difference was found in the content of total polyphenols between treated and control wines. However, some differences were found in the low molecular weight phenolic compounds (LMWPC) but depended on the SIDY used, the ageing period and the LMWPC analyzed. The use of SIDY contributed to improve the colour of wines which had a lower colour intensity and lower values of “a and b” CIELab parameters, which can allow to avoid or reduce the browning of wines.

Acknowledgements: This study was supported by CONICYT-Chile PAI N° 781403003 and FONDECYT N°1140882 Projects.