The minimum medium (MM) consisted of: 1.34%
of yeast nitrogen base without ammonium sulphate
and amino acids (YNB, Difco, Detroit, USA) and 4%
glucose supplied by Merck Farma Quimica (Barcelona,
Spain). The grape variety employed in this study
was Macabeo (Viura), a Spanish variety that produces
a light, acid, floral and fairly fruity white wine whose
aroma and flavour soon dissipate so it should be drunk
quite young. The grape must was treated with 0.4 g
l1 of bentonite for 2 days at 4 8C to clarify it by
sedimentation before fermentation, and inoculated
with 5% of pied du cuve, an overnight preculture of
the yeast in must. The bottles with 250 ml of MM
media or grape must were covered with a sterile twolayer
gauze to avoid contamination, and fermentations
were carried out in duplicate at 18 8CF1 8C for 20