Wine Chemistry and Biochemistry

7 Carbohydrates 243

Myo-inositol

OH OH

OH

OH

OH

OH

Chiro-inositol

OH OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

Scyllo-inositol

Fig. 7.9Structures of the different inositols appearing in wines

2,3-Butanediol is a constituent of wine and an important neutral compound

formed by yeast fermentation of carbohydrates.Saccharomyces cerevisiaeproduces

mainlyD(–)-2,3-butanediol and small amount of themesoform. Wines that had

undergone malolactic fermentation contained traces ofL(+)-2,3-butanediol which

was absent from wines that had not undergone malolactic fermentation (Herold

et al. 1995).

7.6 Sugar Acids

Sugar acids come from enzymatic oxidation of sugars, especially important in wines

affected byBotrytis cynereaand by rot in general; acetic bacteria also produce these

compounds. Some data about their level in wines are presented in Table 7.6.

Gluconic acid is produced by oxidation from glucose; gamma- and delta-

gluconolactones (glucono-1,4-lactone and glucono-1,5-lactone, respectively) are

formed by intramolecular gluconic acid esterification reactions. Both lactones are

Ta b l e 7. 6Acid sugars in wine. Range in mg/L

Different wines

(De Smedt

et al. 1979)

White

(Sponhloz

and Dittrich

1985)

Red

(Sponhloz

and Dittrich

1985)

Sherries

(Sponholz

and Dittrich

1984)

White (Barbe

et al. 2000)

Gluconic 0–2000
(including
lactones)

––––

Gluconolactone – – – – 155–270
Glucuronic – 0–35 0–33 nd –
Galacturonic – 116–1048 381–1200 365–517 –
5-Oxogluconic – 8–92 14–74 tr–5.3 –
2-Oxogluconic – 0–122 0–17 nd–tr –
2-Oxoglutaric – – – – 78–248

nd: not detected
tr: traces