Harnessing wine yeasts: Unveiling their potential as lipid supplements

In industry, clarifying white grape juice may lead to the partial loss of lipids, which yeasts use to alter their plasma membrane composition to overcome the stresses associated with wine fermentation. In this work, a selection of yeasts isolated from the broader wine environment was screened for their lipid composition using flow cytometry, gravimetric assays and GCMS. Inactivated dry yeasts were produced from six of the screened yeast strains and were tested as lipid supplements in over-clarified Chenin Blanc grape juice, alongside pure lipid mixtures matching the lipid concentrations occurring in the inactivated yeasts. Both the addition of the inactivated yeasts and pure lipid mixtures enhanced fermentation performance compared to two controls, one with the reintroduction of fine lees and another with no addition. The improved fermentation performance was largely due to the variation in lipid composition, as the supplementation of some inactivated yeast derivatives led to better fermentation performance than others. A reduction in acetic acid was observed for all additions. Differences in the production of a selection of aroma compounds linked with lipid metabolism were also observed between the addition of pure lipids and inactivated yeasts. Supplementing with inactivated yeasts led to an increase in the production of phenylethyl acetate, isoamyl acetate and hexyl acetate, which are responsible for fruity and floral aromas. This study provides novel insights into the lipid diversity of a selection of yeasts isolated from the broader wine environment and presents these yeasts as potential sustainable lipid supplements in lipid-deficient grape juice.