For the samples treated with yeast lees and YD preparation,
where insoluble particles were present, the reaction with DPPH
has been carried out as suggested by Gallardo-Chacón et al.
(2010): 3 mL of DPPH and 100 lL of sample were introduced in
a test tube; after 10 min, the reaction mixture was filtered on a
0.80 lm nylon membrane and immediately subjected to spectrophotometric
measurement. The initial value of the absorbance
was read by adding 100 lL of methanol: acetate buffer, to 3 mL
of DPPH stock solution.