3. Pediococcus
Some members of this genus
(Pediococcus pentosaceous) can grow in
wine without residual sugar or malic
acid. Sometimes their growth causes a
cosmetic problem only (haziness and
fine sediment), but sometimes biogenic
amines may be produced, or an
unpleasant aftertaste (not mousiness)
may develop. Reds, especially Pinot
Noir, blended shortly before bottling
and not sterile-filtered are most at risk.
4. Brettanomyces/Dekkera
Test for Brettanomyces on a regular
basis before preparing wine for bottling,
to determine whether the population
is increasing or declining, unless
the wine will be filtered with a 0.65 μ
or 0.45 μ membrane. If they grow in
the bottle, Brettanomyces
|
produce a small amount of CO2, which may not
be noticed unless the wine is examined
carefully. Sensory changes in the
bottle can be profound, from 4-EP, 4-
EG, and other metabolites.
Bottle variation is common, with
some bottles showing little Brett character
but other bottles severely
affected, their fruity aromas replaced
by horse-sweat and Bandaid® odors,
accompanied by a bitter, metallic finish.
Interestingly, these characters can
seem to intensify in the bottle even
though the actual levels have not
changed.
Non-wine microbes in the bottle
Microbes that are unable to grow in
wine may survive the inhospitable
environment for a few days to weeks
(or sometimes, months). They
|
make
culturing difficult until they die, for
they may cover or inhibit wine
microbe colonies in culture. Molds
and spore-forming bacteria are common
bottling contaminants, as are
non-wine cocci and some yeasts.
These microbes are important
because their presence can indicate
problems with bottling sanitation,
which can be serious. If more than a
few non-winemicrobes grow onmembrane
filtration cultures after bottling,
a complete evaluation of bottling line
sanitation is recommended to find the
source(s) of infection. |
By Lisa Van de Water
From September/October 2009
By Richard Gibson
From September/October 2009
By Dr. Bruce Zoecklein, Lisa M Pélanne,
Sandy S. Birkenmaier, and Karen Reed
From July/August 2009
By Pat Henderson, Kenwood Vineyards
From January/February 2009
