Wine Chemistry and Biochemistry

288 D. Dubourdieu and T. Tominaga

0

200

400

600

800

1000

0h 3h 6h 14h 19h

P-4MSP and P-4MSPOH

0

20000

40000

60000

80000

100000

120000

P-3SH

P-4MSP

P-4MPSOH

P-3SH

ng eq. /L ng eq. /L

Fig. 8B.8Influence of skin contact on the cysteinylated precursors of the must (Peyrot des
Gachons et al. 2002a)

0

25

50

75

0123456

0

500

1000

1500

ng/L released

days

4MS

POH

4MS

P

3SH

Fig. 8B.9Sauvignon blanc aroma revelation during alcoholic fermentation in practical conditions:
yeast strain VL3c (Tominaga et al. 1998c)

the precursor are very limited (Fig. 8B.10). The molar concentrations of 4-MSP

4-MSPOH, and 3-SH formed in Sauvignon blanc must (or a model medium supple-

mented with precursors) during alcoholic fermentation only account for less than

10% of the precursors degraded (Fig. 8B.11).

To be transformed in aroma, the precursor must enter into the yeast, then be

cleaved by – elimination of the cysteinylated precursor and finally excreted in

the medium where it is more or less stableaccording its reactivity with other com-

pounds. Obviously, the yield of this transformation can be influenced by several