Effect of yeast strain selection on the concentration of cis- and trans-resveratrol and resveratrol glucoside isomers in wine

The influence of four fermentative yeast strains belonging to the Saccharomyces cerevisiae species, on the content of cis- and trans-resveratrol and resveratrol glucoside isomers in Vitis vinifera L. cv. Shiraz grape musts during alcoholic fermentation was studied by reverse phase high performance liquid chromatographic (RP-HPLC) analysis. During vinification an increase in both the free and the glucosidic forms was observed up to day three/five (cis- resveratrol/piceid) or day four (trans- isomers) after which variable yeast, β-glucosidase activity was noted until dryness where a general increase in free forms of resveratrol was accompanied by a decrease in the corresponding glucoside. In the finished wines ready for bottling or aging, the total amount of all resveratrol forms reflected (P<0.05) the manufacturers polyphenol extraction ratings for the strains. Relative extraction of total phenolics in red wine amongst different yeast strains was demonstrated to mimic relative stilbene content.