Fatty acid content of unripe and ripe ‘Pedro Ximénez’Vitis viniferagrapes

Abstract

We studied the fatty acid composition of musts obtained from Pedro Ximénez Vitis vinifera grapes at two ripening stages (unripe and ripe). The overall fatty acid content was found to increase with ripening while the proportion of unsaturated acids decreased. Linoleic acid underwent the most marked decrease in this respect, which reveals that grapes lose some of their potential herbaceous aroma on ripening. Unsaturated fatty acids C16:l, C18:l and C18:2 prevailed in the neutral lipid fraction and their proportions increased with ripening. On the other hand, palmitic acid (C16:0) was preferentially encountered in the polar lipid fraction and its proportion increased with ripening. IntroductionFatty acids in grapes play a major role in wine making, insofar as they are growth and survival factors for yeasts during alcoholic fermentation of musts and a source of aroma compounds for the resulting wine. In fact, they are responsible for the formation of a number of volatile compounds such as aliphatic aldehydes, ketones, alcohols and short-chain fatty acids.The role of fatty acids as growth and survival factors was shown by Stier (1953, 1954), who observed how yeasts under anaerobic conditions multiplied actively on adding certain sterols, oleanolic acid (a triterpene) and long-chain fatty acids to the medium. Bréchot et al. (1971;Bréchot, 1974) showed the stimulating effect of oleic and oleanolic acid on the anaerobic growth of yeasts, and Watson (1982) found that unsaturated fatty acids in yeast membranes rather than ergosterol were responsible for the tolerance of these cells to ethanol. However, Youings and Rose (1989) found that Saccharomyces cerevisiae Y185 requires the presence of sterols

Search for Transcriptional and Metabolic Markers of Grape Pre-Ripening and Ripening and Insights into Specific Aroma Development in Three Portuguese Cultivars

“…However, fatty acid oxidation does not seem to be favored during ripening in pulp and skin but instead fatty acid biosynthesis appeared to be enhanced. Indeed, we have observed at EL 36 and EL 38 an increase in content in several saturated fatty acids (Table 1, File S2) as previously reported for another Vitis vinifera variety [29]. Moreover, genes coding for key enzymes of glyoxalate cycle such as malate synthase and isocitrate lyase were down-regulated though not in all varieties (File S3).…”

“…This enzyme also known as FAD6 is the primary route of polyunsaturated fatty acids production in plants and converts oleic acid (18∶1, a monounsaturated fatty acid) to linoleic acid [33] which provides a potential herbaceous aroma in ripe grapes [29]. In fact, we did not detect a significant decrease in linoleic acid.…”

“…Other fatty acids such as octadecenoic and hexadecanoic also showed no significant differences throughout ripening (File S2). However, in 'Pedro Ximnez' Vitis vinifera grapes hexadecanoic acid (palmitic acid) increased during ripening [29] highlighting metabolic specificities among varieties.…”

Evaluation of Differences in the Aroma Composition of Free‐Run and Pressed Neutral Grape Juices Obtained from Emir (Vitis vinifera L.)

“…The concentration of nonanoic acid and dodecanoic acid were only high in FJ. As reported previously, the amounts of acids in the grape juice are influenced by such different factors as grape variety, pressing, and steeping with grape solids prior to fermentation [20]. Hexadecanoic acid was the most dominant acid in both juices, as it accounted for the largest proportion of the total acid components, followed by acetic and hexanoic acids.…”

Grape Lipidomics: An Extensive Profiling thorough UHPLC-MS/MS Method

“…The wide range of sphingolipid structures enables their function in a variety of cellular processes: from acting as structural integrity elements of the membrane to mediating cellular processes such as programmed cell death, which can be promoted by CER accumulation [60,61]. Moreover, the decreasing trend of DGDG could be linked to the decreasing concentration of linolenic acid during grape maturation [62], indicating an important role of the lipoxygenase pathway in combination with galactolipases and phospholipases during the ripening period [63].…”