Influence of aroma-enhancing yeast nutrients on the volatile profile of important Austrian white wine grape varieties

Abstract

As consumer demands for grape wines increase, it is becoming important for producers to optimise the aroma. Yeast nutrient salts can help to achieve this. While the influence of classic yeast nutrient salts (e.g. diammonium phosphate (DAP)) has been well investigated, there are only a few studies on organic yeast nutrients. The aim of the study is to compare four concepts of yeast nutrition for fermentation: 1) without nutrient; 2) salt nutrition with DAP and thiamine; 3) full nutrition (combined products of yeast autolysates, DAP, and VitB1); and 4) complex nutrition (yeast autolysates with promoted additional function plus DAP) for four important Austrian grape varieties. Around 70 relevant minor and major volatile compounds were analysed. It was shown that the addition of nutrients generally has a positive influence on the volatile composition of the wines. Thiols responded most consistently to nutrient addition, with 3-sulfanylhexan-1-ol increasing by 20–60 % compared with the control. In contrast, full and special nutrient concepts did not outperform simple salt nutrition; their effects on monoterpenes and esters were inconsistent and strongly dependent on the grape–yeast combination. The hypothesis that full or even more expensive special nutrition would consistently yield superior results could not be confirmed. Although three of the four variety groups showed similar behaviour of fu with sp and co with sa, this pattern was not uniformly expressed across all grape–yeast combinations. Future studies with different fermentation conditions (NOPA initial value, fermentation temperature, different yeasts), including an in-depth sensory study, cell growth analysis, a screening of undesired compounds such as biogenic amines and a more comprehensive study including international grape varieties would be useful.