Formation Pathways of Ethyl Esters of Branched Short-Chain Fatty Acids during Wine Aging

Abstract

The particular behavior during wine aging of fermentative branched fatty acid ethyl esters, related to yeast nitrogen metabolism, compared that of their straight-chain analogues, related to yeast lipid metabolism, was first checked in 1-5 year aged Muscadet wines. Quantitative SIDA measurements showed that the levels of the former increased, whereas those of the latter decreased. Then, three hypothetical pathways suggested in the literature to explain these variations of branched esters were investigated. Two Muscadet and Sylvaner wines were spiked with levels of deuterated isobutanoic acid and its ethyl ester, similar to those of their natural analogues, then they were submitted to model aging. Quantitative SIDA measurements on the formation of these natural and labeled ethyl esters from the corresponding acids revealed that the behavior of the natural and labeled compounds were similar. The acid levels were much higher than the ester levels in the initial young wine, and a significant upward trend of their esterification ratios to those of the acid-ester equilibrium was observed with aging. Thus, this equilibrium proved to be the most effective in generating the branched fatty acid ethyl esters during wine aging. In contrast, the formation of these acids by Strecker-type degradation of wine amino acids in the conditions of the model aging or by hydrolysis of their glycoconjugates proved to be ineffective.

Evolution of aromatic compounds during the second fermentation and aging of Brazilian sparkling wine

“…In general, volatile fatty acids concentration increased during second fermentation, declined during the first months of aging, and increased again after nine months. Conversely, the concentration of ethyl esters of fatty acids which are described as fruity and pleasant aromatic compounds significantly decreased after nine month of aging, contributing to the overall loss of "fresh", "fruity" and "flowery" notes on aged wines [18]. This peculiar behavior of fatty acids and ethyl esters can be attributed to the adsorption by the lees [6], and the release during autolysis [1,19].…”

Effect of grape bunch sunlight exposure and UV radiation on phenolics and volatile composition of Vitis vinifera L. cv. Pinot noir wine

“…Among the esters determined, ethyl esters of fatty acids and higher alcohol acetates contribute global ''fruity'' notes to wine (Perestrelo et al, 2006). Ethyl esters of fatty acids are formed from ethanolysis of acyl CoA that is formed during fatty acid synthesis or degradation (Diaz-Maroto, Schneider, & Baumes, 2005;Perestrelo et al, 2006), while acetate esters are formed from the reaction of acetyl CoA with higher alcohols that are generated from degradation of amino acids or carbohydrates (Vianna & Ebeler, 2001). Esters of branched-chain acids including ethyl 2-methylpropanoate, ethyl 2-methylbutanoate and ethyl 3-methylbutanoate were determined in this study.…”

Quantitative determination of five hydroxy acids, precursors of relevant wine aroma compounds in wine and other alcoholic beverages

“…As both families of compounds are interrelated due to the esterification/hydrolysis equilibrium [ 6 , 7 ], relevant aroma changes can take place during ageing if they are initially present at concentration ratios different to that of the corresponding esterification equilibrium [ 8 ]. This is certainly the case of ethyl 2 , 3 and 4 methylpentanoate and ethyl cyclohexanecarboxylate which were described by Campo et al as responsible for powerful strawberry aromas in aged wines and spirits [ 9 , 10 ].…”