Interactions between aroma compounds and whole mannoprotein isolated from Saccharomyces cerevisiae strains

The interactions of four wine aroma compounds (isoamyl acetate, hexanol, ethyl hexanoate, beta-ionone) either with a whole mannoprotein extract or with mannoprotein fractions at a level encountered in wine (150 mg/L) were studied by dynamic and static headspace techniques. The mannoproteins were isolated from a synthetic medium subjected to an alcoholic fermentation with two etiological yeast strains. They were fractionated by exclusion chromatography and characterized through glycosyl composition analysis. While the volatility of isoamyl acetate was affected neither by whole extracts nor by mannoprotein fractions, a significant decrease of the volatility (up to 80%) was observed for the other aroma compounds. If the behaviour of mannoproteins towards ethyl hexanoate differed between the two strains, a similar retention was found for the other compounds. The retention level was not the same when whole mannoprotein extract and isolated mannoprotein fractions were used, suggesting the possible interactions between mannoprotein fractions. (c) 2005 Elsevier Ltd. All rights reserved.