Flextank HDPE Maturation Vessels - Australian & International Trial Updates
fermentation & maturation
trials with white wine
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WINE TRIALS IN AUSTRALIA: An excellent summary of a typical set of wine trials is given in the below article. (Click on the image to open a downloadable pdf)
Flextank maturation tanks require the addition of oak to allow the wine to develop oak-derived flavours that occurs in the barrel maturation process. High quality staves are recommended for this process. Further, the Flextank maturation process with staves will be less at risk from other problems, including losses due to evaporation and development of Brett off-flavours, than can occur during oak barrel maturation.
On the other hand, if oak staves are not
added to the wine in Flextanks, the
maturation process becomes similar to that
occurring in a neutral or spent barrel: the
advantage of Flextank maturation, apart from
much improved hygiene over use of old
barrels, is that oxygen ingress is closer to
that of a new barrel, allowing wine
development to occur to a more normal
timetable.
TRIAL 1: A 2006 Shiraz, after malo-lactic fermentation, was added to the following vessels:
All vessels were kept in the same storage
area (same temperature and humidity) for the
eleven months duration of the trial. The
intention of the trial was to monitor
relative changes in various chemical
parameters for the wines stored in the
different vessels.
Free sulfur dioxide concentration
(mg/litre) in 2100 litre Flextanks (BP01,
BP02, BP03), 1000 litre Flextanks (BP05,
BP06)
The free sulfur dioxide concentrations were
essentially the same in all storage vessels
after the 11 month maturation period.
Importantly, the rate of free sulfur dioxide
loss in the first five months occurred at
the same rate for the oak and Flextank
vessels, showing the validity of Flextank's
oxygen permeation physics and vessel
designs.
There was no significant difference in wine
colour density after 11 months, while the
wine hue was higher in the Flextank vessels
in comparison to the oak vessels. Levels of
oak volatiles increased during the time
course of the maturation study, irrespective
of storage vessel type.
The concentrations of free dimethyl sulfide
in the Flextank vessels were slightly, but
not significantly, higher than in the oak
vessels (8 to 10 microgram/litre compared to
6 microgram/litre). The measured
concentrations of hydrogen sulfide were the
same in all vessels and the levels of
methanethiol were below detection.
TRIAL 2:
This trial focussed on maturation of a 2007 Shiraz wine with subsequent sensory assessment for classification into wines for two retail price points: $40 and $15. The wine was stored in the following vessels for 7 months of maturation:
The resulting wines were assessed blind by 5
winemakers using the International 20 point
scoring system (maximum score = 20). The
results were:
The results of this trial clearly
demonstrate the success of Flextank vessels
for the maturation of high value wine.
TRIAL 3:
A 2008 vintage Shiraz was placed in several different vessels near the end of the primary ferment for 4 months maturation. The vessels used were:
The wines were tasted for allocation by five
winemakers and scored using the
International 20 point scoring system. The
wine in Flextank received a 'gold medal'
(that is, a score of 18.5/20 or higher), the
wine in barriques received a 'silver medal'
and that from the stainless steel, a bronze
medal.
In both of the above trial cases the
winemakers judged the wine matured in
Flextank to exceed the quality of the wine
matured in French oak barrels. The outcome
of both trials confirmed the ability of
Flextank vessels to mature wine destined for
the even the top price points in the market
place.
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