8D Yeasts and Wine Flavour 367
Ta b l e 8 D. 9 Comparison of aroma descriptorsafor Chardonnay wines made withSaccharomyces
cerevisiaeand non-Saccharomycesspecies
Aroma descriptorsAroma group Saccharomyces cerevisiae Non-Saccharomyces speciesb
Fruity Tropical fruit, ethyl acetate, Stone fruit, apple cider, toffee apple,
pineapple, banana, pear quince, dried pear, floral, fruity ester,
banana ester,ethyl acetate, cooked
apricot,pineapple
Citrus Citrus, lime Citrus peel, cooked orange, lime
Aged Honey Brandy, caramel, honey
Microbiological Sweat, dirt, malt, bread, dough,
meat, salami, sauerkraut
aCompiled from Jane et al. (1996); Henschke et al. (2002); Soden et al. (1999)
bCandida krusie, Candida stellata and Torulaspora delbrueckii
reported the production of wines with different characteristics according to the inoc-
ulation procedure (see, for example, Ciani et al. 2006; Gill et al. 1996; Heard 1999;
Herraiz et al. 1990; Jolly et al. 2003, 2006; Soden et al. 2000; Zironi et al. 1993;
Zohre and Erten 2002). Successful co-fermentation depends on knowledge of the
physiological properties of each yeast, especially compatibility, and consequential
effects on growth rate and biomass development. Suppression of one yeast by the
other can result in reduced metabolic activity and hence lessened impact on the
wine characteristics. Indeed, sequential fermentation can be used to favour weak
fermentative strains by delaying inoculation ofSaccharomyces cerevisiae.Candida
stellataonly impacted on the chemical and sensory composition of wine when
inoculated prior toSaccharomyces cerevisiaecompared to coinoculation (Soden
et al. 2000). On the other hand, coinoculation of a weakly fermentative yeast at high
ratio to a strongly fermentative yeast can also achieve greater impact of the former
yeast. In practice, sequential fermentations are easier to manage in the winery and
although the wine can be out of balance, it nevertheless provides a useful aroma
component for improving the complexity of the final blend. In our experience, few
non-Saccharomycesferments require inoculation with aSaccharomycesyeast due
to the presence of a sufficientSaccharomycesindigenous population in the juice or
must.
Several examples of how the novel properties of non-Saccharomycesyeasts can
be used to improve the composition and aroma properties of wine will be discussed
according to yeast species. The salient characteristics of several non-Saccharomyces
species are summarised in Table 8D.10.
Torulaspora delbrueckii (anamorpCandida colliculosa;formerlySaccharomyces
rosei)has a moderate tolerance to ethanol (<12.5 vol.%; Table 8D.6) and produces
wines which resemble those made withSaccharomyces cerevisiae. Production of
higher alcohols is however highly variable and strain dependent. Because this yeast
produces comparatively low concentrations of acetic acid, ethyl acetate, acetalde-
hyde and acetoin, its potential suitabilityfor wine production has been suggested
by several studies (Cabrera et al. 1988; Ciani and Ferraro 1998; Herraiz et al. 1990;