FOOD MICROBIOLOGY www.elsevier.nl/locate/jnlabr/yfmic Food Microbiology 21 (2004) 257–265 Release of glycosidically bound flavour compounds of Chardonnay by Oenococcus oeni during malolactic fermentation Nadia D’Incecco a,b,1 , Eveline Bartowsky b, *, Stella Kassara b , Anna Lante a , Paolo Spettoli a , Paul Henschke b a Department of Agricultural Biotechnology, University of Padova, Padova, Italy b The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, SA 5064, Australia Received 1 August 2003; received in revised form 7 September 2003; accepted 7 September 2003 Abstract Glycosidases, produced by Oenococcus oeni strain Lalvin EQ54 during malolactic fermentation (MLF) performed in a chemically defined wine (CDW) medium, contributed to the release of volatile aglycons from their glycosylated precursors, present in a Chardonnay wine glycosidic extract. The liberation of wine volatiles during MLF was limited by the low activity of these enzymes in this strain. Six different aglycons examined were 3-hydroxydamascone, alpha-terpineol, vanillin, methyl vanillate, 4-hydroxybenzoic acid and tyrosol. Using p-nitrophenyl synthetic substrates, it was shown that O. oeni Lalvin EQ54 has b-glucosidase, and limited a-l-rhamnopyranosidase and a-l-arabinofuranosidase activities. Release of aglycons from the Chardonnay wine glycosidic extract was increased when purified a-l-rhamnopyranosidase and a-l-arabinofuranosidase were added to the CDW medium together with the malolactic bacteria culture. The results obtained confirmed that O. oeni has the necessary glycosidases for the sequential liberation of the disaccharide sugars from wine glycosides. The rate of MLF proceeded much faster in the CDW supplemented with the Chardonnay wine glycoside extract (8 days compared to 20 days), even though the bacterial growth was unaffected. r 2003 Elsevier Ltd. All rights reserved. Keywords: Malolactic fermentation; Oenococcus oeni; Disaccharide glycoside; Flavour; Monoterpene; Norisoprenoid; Chardonnay 1. Introduction The complex array of aroma and flavour compounds found in wine largely originate from the grape, yeast metabolism during alcoholic fermentation and oak when used. Bacterial metabolism during malolactic fermentation (MLF) contributes to wine flavour by the formation of additional compounds and the modifica- tion of grape-, yeast- and oak-derived compounds (Laurent et al., 1994; de Revel et al., 1999; Maicas et al., 1999; Bartowsky et al., 2002a,b; Boido et al., 2002). Many wine volatile compounds can be released from their flavourless glycoconjugate precursors by either acid or enzymic hydrolysis (Sefton et al., 1993). These glycoconjugates can be either monoglucosides or dis- accharide glycosides where glucose is further substituted with a-l-arabinofuranosyl, a-l-rhamnopyranosyl, b-d- xylopyranosyl or b-apiofuranosyl, which is then bound to the aglycon. Numerous aglycons have been identified from hydrolysis of wine and grape juice glycosides, including monoterpenes, norisoprenoids, aliphatics and phenolic compounds (Williams, 1993). The general structure of the glycosides is shown in Fig. 1. The glycosidases which are involved with the enzymic cleavage of the disaccharide glycosides include a-l- arabinofuranosidase (EC 3.2.1.55), a-l-rhamnopyrano- sidase (EC 3.2.1.40) and b-d-glucopyranosidase (also referred to as b-d-glucosidase) (EC 3.2.1.21). The release of many of these compounds is important to the flavour of wines of certain grape varieties (Williams et al., 1989) as well as to that of other alcoholic beverages (brandy) (Stahl Biskup et al., 1993) and fruit juices (apple, apricot, peach) (Schwab and Schreier, 1990; Krammer et al., 1991). G . unata et al. (1988) have demonstrated that the release of the volatile aglycon from the ARTICLE IN PRESS *Corresponding author. Tel.: +61-8-8303-6600; fax: +61-8-8303- 6601. E-mail address: eveline.bartowsky@awri.com.au (E. Bartowsky). 1 Present address: Food Spectrum, 53 Fairlawn Street, Nathan, Qld. 4111, Australia. 0740-0020/$-see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.fm.2003.09.003