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introduction
wine trials in australia
wine trials in germany
wine trials in switzerland
fermentation & maturation
trials with white wine
oxygen permeable rates
other polyethylene vessels
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The Flextank controlled permeation tanks for wine
maturation have been used increasingly widely in
Australia over several years. International sales
are also increasing. The following reviews the
concept of Flextank maturation vessels and
summarises the outcomes of recent wine trials
carried out in Australia and Europe. The results of
these trials clearly show that taint, so often a
criticism leveled at 'plastic' tanks, is not an
issue with wine stored in Flextanks. The trials also
confirm that Flextanks equal or exceed oak barrels
for wine maturation for quality wine development.
For best results, emphasis must be placed on the
selection, origin, number and use of the oak used in
the Flextanks, considerations similar to barrel
selection. The ability to tailor vessels with
specific oxygen permeation rates to suit a
particular wine style is described.
Introductory link: 'Getting Tanked' - Age
'Epicure' article by Jeni Port
The selection of the thermoplastic polymer
used by Flextank is the result of
substantial theoretical and trial work: it
is an ultra-clean, food grade high-density
polyethylene that has received approval for
liquid food and wine use specifically. It
has also been extensively trialled. The
materials development process also required
consideration of each production step to
ensure that the polymer had the right sinter
density and was not degraded during the
moulding step. Other considerations included
lifespan of the products and ease of use
aspects such as internal surface finish and
tartar non-adhesion. The precise makeup of
the Flextank polymer is commercially
sensitive.
Tanks made more than twenty years ago were
in fact not thermoplastic, but were actually
made from thermosetting polyester resin
mixed with glass fibres. The solvents and
catalysts used, if extracted into wine,
could lead to a distinct taint. Food grade
thermoplastic polymers like polyethylene are
a different material entirely. They contain
no free solvents or other reagents that can
migrate into wine.
The absence of taint in wine stored in
Flextank maturation tanks has been confirmed
by winemakers from various trials with, in
one case, the wine being stored for three
years. Not all trials are fully replicated
and this always limits the depth of
information that can be extracted from the
data. But, in the words of one Australian
winemaker, "we found that they (Flextanks)
don't taint".
Chemical analysis of wine stored in
Flextanks has shown that there is no
difference in the general wine quality
parameters for wine stored in Flextank, oak
or stainless steel. Of particular note,
chlorophenols, a concern often expressed
with the use of plastic materials in wine
production, were not found in Flextank-matured
wine.
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