Protective agents used to reverse the metabolic changes induced in wine yeasts by concomitant osmotic and thermal stress

Aims: The reversion of the metabolic changes induced in wine yeasts by stressors. Methods: Six strains of Saccharomyces were inoculated in grape must containing over 400 g l(-1) of sugar and incubated at 35 degreesC, both with and without the addition of 100 mg l(-1) of catechin, inositol or SO2 . Results: Significant correlations between addition of the stress-protectants and change in the metabolic behaviour of the wine yeasts were observed. Depending on strain and protectant, and expressing data as a percentage of increase or decrease compared to the control, fermentation vigour after 3 d increased by up to 10%, titratable acidity of the wines increased by up to 7%, ethanol content increased by up to 20%, unitary acetic acid production decreased by up to 35%, and unitary glycerol production decreased by up to 20%. Impact of Study: By using protective agents it is possible to minimize the abnormal fermentation performance that wine yeasts exhibit under thermal and osmotic stress.