Effect of free fatty acids and lipolysis on Sauvignon Blanc fermentation

Abstract

Background and Aims The volatile thiols, such as 3‐mercaptohexanol, 3‐mercaptohexyl acetate and 4‐mercapto‐4‐methylpentan‐2‐one, are major aroma compounds responsible for the distinctive tropical notes (passionfruit and grapefruit) in New Zealand Sauvignon Blanc wines. Previously, it was observed that traces of linoleic acid in grape juice can significantly affect the development of these volatile thiols and other aroma compounds in wine. Here, we examined the effect of the fatty acids commonly found in Sauvignon Blanc grape juice as well as juice lipid lipolysis on the development of aroma compounds in the resulting wines. Methods and Results Experiments were performed to increase the total free fatty acid concentration in grape juice through juice treatment with acidic lipase from Aspergillus niger and through co‐cultured fermentations with non‐Saccharomyces lipase‐secreting yeasts. We observed a significant reduction in the production of 3‐mercaptohexyl acetate in fermented wines upon supplementation with linoleic acid and lipase. Supplementation with lipase increased the concentration of 3‐mercaptohexanol and all ethyl esters detected, while reducing the development of acetate esters. Co‐cultured fermentations also affected the development of many classes of aroma compounds. Conclusions This study demonstrated that the aroma profile of wines could be effectively manipulated by altering the amount of free unsaturated fatty acids in grape juice through lipolytic enzyme supplementation or co‐fermentation with non‐Saccharomyces lipolytic yeast species. Significance of the Study The key findings of this study may lead to new winemaking strategies through the manipulation of the lipid component of grape juice.

Qualitative Factor-Based Comparison of NMR, Targeted and Untargeted GC-MS and LC-MS on the Metabolomic Profiles of Rioja and Priorat Red Wines

“…Regarding this factor, studies such as [ 34 ] have shown significant differences in the aroma after comparing wine ageing in oak barrels and glass bottles with a trained tasting panel. However, in the current study, among these metabolites, the ones that have been connected to aromatic characteristics are palmitic acid, stearic acid, and 1-dodecanol [ 35 , 36 ] all of them having higher concentrations in the bottle-aged wines.…”

Grape and Wine Metabolomics to Develop New Insights Using Untargeted and Targeted Approaches

“…Using a GC-MS-based metabolomics approach, they showed that increased concentration of linoleic acid affected different primary (e.g., amino acids) and secondary metabolites (e.g., varietal thiols and acetate esters) in a strain-specific manner. Another experiment from the same laboratory also revealed that pre-supplementation of different saturated and unsaturated fatty acids during Sauvignon blanc fermentation significantly affected the metabolism of wine yeast and as a result, end product formation [141]. These metabolomics studies together generated an awareness for the wider wine industry to select wine yeast based on the juice composition in order to obtain wines with desired aromatic profiles.…”

“…Over the past decade, many metabolomics studies have been carried out to determine effect of juice or growth media composition on overall wine yeast metabolism, with particular attention on the developments of fermentation end products [107,108,141]. For instance, two publications from a research group of the University of Auckland reported changes before and after fermentation in Sauvignon blanc juices and how juice composition influences the major varietal aroma compound production by Saccharomyces cerevisiae EC1118 [34,107].…”

“…The influence of different groups of metabolites, particularly amino and fatty acids, and fermentation conditions on winemaking and also on wine yeast metabolism is a well-studied area [108,141,[147][148][149][150][151]. A considerable amount of new knowledge has been generated in this matter mostly by using targeted metabolomics or a metabolite-analysis approach.…”

“…A considerable amount of new knowledge has been generated in this matter mostly by using targeted metabolomics or a metabolite-analysis approach. Most of these studies were performed either using a natural grape juice medium [108,141] or grape juice-like synthetic media [149,150]. Casu, Pinu, Fedrizzi, Greenwood and Villas-Boas [108] investigated the effect of pre-fermentative supplementation of an unsaturated fatty acid, linoleic acid, on the metabolism and aroma compound production by three different wine yeast strains.…”