Alcohols, esters and heavy sulphur compounds production by pure and mixed cultures of apiculate wine yeasts

Abstract

Strains of Hanseniaspora uvarum, Hanseniaspora guilliermondii and Saccharomyces cerevisiae were used as pure or mixed starter cultures in commercial medium, in order to compare their kinetic parameters and fermentation patterns. In pure and mixed cultures, yeasts presented similar ethanol yield and productivity. Pure cultures of H. uvarum and S. cerevisiae showed a specific growth rate of 0.38 h(-1); however, this value decreased when these yeasts were grown in mixed cultures with H. guilliermondii. The specific growth rate of pure cultures of H. guilliermondii was 0.41 h(-1) and was not affected by growth of other yeasts. H. guilliermondii was found to be the best producer of 2-phenylethyl acetate and 2-phenylethanol in both pure and mixed cultures. In pure cultures, H. uvarum led to the highest contents of heavy sulphur compounds, but H. guilliermondii and S. cerevisiae produced similar levels of methionol and 2-methyltetrahydrothiophen-3-one. Growth of apiculate yeasts in mixed cultures with S. cerevisiae led to amounts of 3-methylthiopropionic acid, acetic acid-3-(methylthio)propyl ester and 2-methyltetrahydrothiophen-3-one similar to those obtained in a pure culture of S. cerevisiae; however, growth of apiculate yeasts increased methionol contents of fermented media.

The Role and Use of Non-Saccharomyces Yeasts in Wine Production

“…These, and other compounds not discussed in this article (e.g. volatile fatty acids, carbonyl and sulphur compounds), are known to play a role in the sensory quality of wine (Nykänen, 1986;Lambrechts & Pretorius, 2000;Moreira et al, 2005). However, as stated by Guth (1997), there are over 680 documented compounds in wine and a large number of these can, depending on their concentrations, contribute either positively or negatively to wine aroma and flavour.…”

“…The range of flavour compounds produced by different yeasts is well documented (Castor, 1954;Suomalainen & Lehtonen, 1979;Soles et al, 1982;Nykänen, 1986;Rauhut, 1993;Romano & Suzzi, 1993a;Lambrechts & Pretorius, 2000;Rojas et al, 2003;Romano et al, 2003;Moreira et al, 2005;. The metabolic products resulting from non-Saccharomyces growth include glycerol, acetaldehyde, acetic acid, succinic acid, higher alcohols and fatty acid esters (Fleet et al, 1984;Bisson & Kunkee, 1991;Jackson, 1994;Boulton et al, 1996;Lonvaud-Funel, 1996;Heard, 1999;Zohre & Erten, 2002;Clemente-Jimenez et al, 2004).…”

A Method to Discriminate Between the Candida stellata and Saccharomyces cerevisiae in Mixed Fermentation on WLD and Lysine Agar Media

“…Currently, different culture agar media are used, either selective or differential, which allows some discrimination between the different microorganism species involved in a wine fermentation. WL nutrient agar (Cavazza et al, 1992;Pallmann et al, 2001;Romancino et al, 2008), YM agar (Soden et al, 2000;Moreira et al, 2005) and YEPD (Ciani et al, 2006;Perez-Nevado et al, 2006) media are generally used to count total yeasts present in an oenological sample. The same media appropriately modified by the addition of an antimycotic or antiseptic (Moreira et al, 2005;Perez-Nevado et al, 2006) are selective and allow the counting of resistant yeasts.…”

“…WL nutrient agar (Cavazza et al, 1992;Pallmann et al, 2001;Romancino et al, 2008), YM agar (Soden et al, 2000;Moreira et al, 2005) and YEPD (Ciani et al, 2006;Perez-Nevado et al, 2006) media are generally used to count total yeasts present in an oenological sample. The same media appropriately modified by the addition of an antimycotic or antiseptic (Moreira et al, 2005;Perez-Nevado et al, 2006) are selective and allow the counting of resistant yeasts. Instead, lysine agar (Morris & Eddy, 1957;Fowell, 1965;Heard & Fleet, 1986;Cavazza et al, 1992;Soden et al, 2000;Ciani et al, 2006) allows the counting of all the yeasts that are able to use lysine as the only nitrogen source.…”

“…It follows that two medium types (selective and non-selective) are generally used together, as the information provided is complementary and allows the researchers to trace in some detail the fermentation trend. However, some selected media show an area of application that is restricted to only a few yeast species or genera (Moreira et al, 2005;Perez-Nevado et al, 2006), while when there are < 10 4 Saccharomyces cells/plate on lysine agar the individual cells develop into small colonies that may be mistaken for wild yeast colonies (Morris & Eddy, 1957;Fowell, 1965). Cavazza and Poznansky (1998) reported that C. stellata species grow on WL with a morphological distinction, grow on lysine agar and also on WL differential (WLD) equal to WL medium but containing cycloheximide, a yeast inhibiter active on a large number of yeast species.…”