Wine Chemistry and Biochemistry

8D Yeasts and Wine Flavour 317 8D.2.1 Nutrients Saccharomycesspecies can grow on a minimal range of organic and inorganic nutrie ...

318 M. Ugliano and P.A. Henschke phosphate affects flavour metabolism. Similarly, metal ions primarily function as cofactors in ...

8D Yeasts and Wine Flavour 319 Ta b l e 8 D. 2Summary of yeast metabolic interactions with grape compounds Reaction Enzyme/metab ...

320 M. Ugliano and P.A. Henschke Esterification reactions involving alcohols are also favoured by yeast but the rea- son why thi ...

8D Yeasts and Wine Flavour 321 Hashizume and Samuta 1999). 3-Isobutyl-2-methoxypyrazine (IBMP) is the dom- inant compound and is ...

322 M. Ugliano and P.A. Henschke for sugar to alcohol is: 16.83 g/L sugar produces 1 vol. %alcohol (Rib ́ereau-Gayon et al. 2000 ...

8D Yeasts and Wine Flavour 323 (Nieuwoudt et al. 2002). The sensory impact of glycerol is not entirely clear. Effects on perceiv ...

324 M. Ugliano and P.A. Henschke dihydroxy- acetone phosphate glucose glyceraldehyde 3-phosphate glycerol 3-phosphate glycerol p ...

8D Yeasts and Wine Flavour 325 over use of SO 2 , stimulates glycerol production (Bataillon et al. 1996). Due to its essential r ...

326 M. Ugliano and P.A. Henschke acetate glucose oxalacetate pyruvate acetaldehyde Pdcp NAD+ L-malate CO 2 ATP ethanol acetyl-Co ...

8D Yeasts and Wine Flavour 327 determined but environmental conditions modulateL-malate metabolism; produc- tion is favoured by ...

328 M. Ugliano and P.A. Henschke volatile compounds are also released from non-volatile grape flavour precursor com- pounds by y ...

8D Yeasts and Wine Flavour 329 example, the ethyl esters ethyl hexanoate, ethyl octanoate, ethyl decanoate, the branched-chain e ...

330 M. Ugliano and P.A. Henschke and ethyl decanoate, which have an apple, fresh fruit aroma. Interestingly, while deletion of o ...

8D Yeasts and Wine Flavour 331 production which however decreases at higher addition levels (>5 vol.%) (Houtman and Du Plessi ...

332 M. Ugliano and P.A. Henschke Empirically, it has long been known thatlower fermentation temperature pre- serves the fruity c ...

8D Yeasts and Wine Flavour 333 8D.4.2 Higher Alcohols 8D.4.2.1 Significance Higher alcohols, sometimes referred to as fusel alco ...

334 M. Ugliano and P.A. Henschke R | C = O | COOH R | H – C – NH 2 | COOH R | H – C = O R | H –C –OH | H NH 3 CO 2 NADH NAD+ Ami ...

8D Yeasts and Wine Flavour 335 8D.4.2.3 Modulating Factors Many factors affect formation of higher alcohols during fermentation, ...

336 M. Ugliano and P.A. Henschke role in wine quality (Eglinton and Henschke 1999). Concentrations vary widely (<0.2 to>2. ...