Effects of Adding Unsaturated Fatty Acids on Fatty Acid Composition of Saccharomyces cerevisiae and Major Volatile Compounds in Wine

Abstract

The synergistic influences of three unsaturated fatty acids (UFAs, namely linoleic acid, oleic acid and linolenic acid) on the fatty acid composition of Saccharomyces cerevisiae and major volatile compounds were investigated in synthetic grape juice. The addition of UFAs led to a corresponding increase in UFAs in the cellular lipid, which was accompanied by a reverse reduction in the content of medium-chain saturated fatty acids (C6:0 to C14:0) and little variation in that of long-chain saturated fatty acids (C16:0 to C24:0). The supplementation of UFAs considerably improved yeast growth and fermentation activity and, in particular, increased the concentrations of most volatile compounds in wine, including higher alcohols (2-phenylethanol, 2-methyl-1-propanol and 3-(methylthio)-1-propanol), medium-chain fatty acids (butanoic acid, hexanoic acid and octanoic acid), acetate esters (isoamyl acetate and 2-phenylethyl acetate) and all ethyl esters. Remarkable linear relationships were further found between ethyl esters and the concentration of the added UFAs (R 2 from 0.909 to 0.996), which significantly intensified the fruity, flowery and sweet attributes of the final wine, as assessed by calculating the odour activity values. Our results suggest that rationally increasing the concentration of UFAs is not only a practical method to improve yeast fermentation activity, but also a potential approach to manipulating wine aroma.

Effect of the addition of branched-chain amino acids to non-limited nitrogen synthetic grape must on volatile compounds and global gene expression during alcoholic fermentation

“…It is well known that the accumulation of precursors, higher alcohols and MCFAs in the medium can promote the production of acetate esters and ethyl esters, respectively (Mouret et al 2014, Duan et al 2015. This could mainly explain the higher concentration of esters produced in wine with addition of BCAAs (Table 5), although few genes related to production of esters were induced.…”

“…In contrast, it has been confirmed that higher yeast biomass can guarantee greater fermentation activity and promote the production of aroma compounds, including higher alcohols and esters (Varela et al 2004, Duan et al 2015. The increase in yeast biomass could therefore partially contribute to the increase in volatile aroma compounds in fermentations with added BCAAs.…”

“…Glucose, ethanol, glycerol, acetic acid, malic acid, lactic acid and succinic acid in the fermentation samples were quantified with HPLC (Agilent Technologies, Santa Clara, CA, USA) equipped with an HPX-87H Aminex ion-exchange column (300 mm × 7.8 mm, Bio-Rad Laboratories, Hercules, CA, USA) (Duan et al 2015). The mobile phase was 5 mmol sulfuric acid.…”

“…Volatile compounds from wines were analysed using headspace solid-phase microextraction (SPME) coupled with GC/MS, which was previously developed by Zhang et al (2011) in our laboratory. This method has high accuracy, reproducibility and efficiency for the quantification of volatile compounds in wine (Duan et al 2015. Samples were extracted with 50/30 μm DVB/CAR/PDMS fibre (Supelco, Bellefonte, PA, USA).…”

Use of solid phase microextraction to identify volatile organic compounds in brazilian wines from different grape varieties

“…These compounds can directly contribute to the flavour of wine, or serve as substrates that participate in the formation of ethyl acetates. The C6, C8 and C10 medium-chain fatty acid ethyl esters are important flavour-active metabolites that are responsible for the highly desired fruit aroma character in wine (Duan et al, 2015). Fatty acids have also been described with fruity, cheesey, fatty and rancid notes.…”