Note to Cold Soak By Thomas Henick-Kling Professor of Enology A
note of precaution to using cold soak The recent rains and
earlier powdery mildew infections have caused damage to some
grapes, the grape surface is punctured, microorganisms have
entered the interior of the berries. For this to occur, we do
not need clearly visible mold infection, even some slight growth
of fungal hyphae in the surface layers of the berry is
sufficient to open it up to spoilage yeast and bacteria. Studies
at Cornell University have shown us that such damage by powdery
mildew (and following Botrytis) will bring grapes that have a
much higher load of yeast and bacteria than healthy undamaged
fruit. The damaged fruit can have more than several million
yeast per milliliter of juice compared to healthy fruit which
has several hundred or at most several thousand yeast per
milliliter. In addition, these yeast are not the friendly wine
yeast, Saccharomyces cerevisiae, instead, they are mostly
Kloeckera sp (Hanseniaspora sp), Pichia sp,