Day 1: Tuesday, May 4th, 2021 – 10:20 am
Selection and screening of yeasts for Sauvignon Blanc wines
Sauvignon Blanc is one of the most widespread, popular and aromatic varieties throughout the world. Characterized by particularly strong but also very sensitive varietal flavors such as polyfunctional thiols whose perception thresholds are very low; winemakers are looking for more and more balanced fruitiness and greenness coming from the fermentation process in order to maximize consumer’s attraction. The choice of the yeast strain as well as the fermentation parameters are crucial to achieve their goal. This work presents a full study from the screening of a yeast bank collection towards genetic (IRC7 gene expression) and phenotypic (H2S, SO2, volatile acidity productions…) features to the characterization of the best strains through several lab- and micro-scale vinifications (aromatic and sensory attributes), dry yeast quality tests (E2U™ process) then extensive field trials. The results showed that there was first a strong correlation between the zygosity of the short or full-length allele of IRC7 (IRC7S or IRC7L) and the capabilities of the strains to release thiols, especially the 4-mercapto-4-methylpentan-2-one (4-MMP) imparting box tree, passion fruit aromas. Very different potentials to produce undesirable compounds in addition to acetate and ethyl esters were as well observed and lead to the selection of a IRC7L/IRC7L strain (A) mainly promoting all aromatic thiols and complex ethyl esters.