Home' Grower : February 2013 Contents The South Australian Grower -- February 2013
DEMAND for low alcohol
and low calorie wine is
developing, driven by
the public's concerns about
health risks and alcohol abuse,
the threat of volumetric taxes
based on alcohol content and
warmer climates that lead to
increased alcohol levels in wine.
Vladimir Jiranek from the
School of Agriculture, Food and
Wine at the University of
Adelaide told the Crush 2012
conference in Adelaide late last
year that traditional methods for
removing alcohol post-
fermentation can have adverse
effects on the aroma and flavour
profile of treated wine.
"Generally, such products are
disappointing -- at the very least
they exhibit a loss of mouthfeel
or palate weight due to the
removal of alcohol," Professor
New methods that attack the
potential yield of alcohol earlier
in the production chain or help
boost or preser ve flavour are
being developed. Prof Jiranek
predicted that this topic will
remain a high priority for the
industry in the future.
The obvious place to start
looking for ways to produce low
alcohol wines is in the vineyard.
Australian Wine Research
Institute viticulture consultant
Peter Dry outlined the options
available to growers at Crush
Dr Dry said the rate of sugar
accumulation in grape berries is
largely determined by the ratio of
leaf area to fruit weight.
However, flavour and phenolic
ripeness may be independent of
As a consequence, a relatively
high leaf area to fruit weight
ratio may cause sugar to reach an
unacceptably high concentration
by the time flavour or phenolic
ripeness is ready for har vest.
In theory, it should be possible
to delay sugar accumulation
relative to other compositional
changes during ripening, so as to
achieve wines of lower alcohol
concentration without any
untoward effects on flavour and
structure, Dr Dry said.
Options worth considering
include canopy management,
anti-transpirant sprays and timing
irrigation to delay sugar
A sur vey of the scientific
literature produced a few clues to
producing low alcohol wine.
In a trial on cabernet sauvignon
in northern California, fruit
bunches were thinned at three
levels three weeks after fruit set.
Treatments were described as
undercropped, balanced and
Fruit quality was reported as
the ratio of dark to green fruit
where green --
isobutylmethoxypyrazine -- is
undesirable and dark - ß-
damascenone -- is desirable.
The balanced treatment
produced darker fruit at about 24
Brix, with similar ripeness to
undercropped treatments at 27.5
Brix. The overcropped treatment
contained more green odours at
a Brix of about 26.
In a further bunch thinning
trial in California, grapes were
made into wine at four yield and
five Brix levels. Wine made from
balanced vines had the most
desirable berr y colour, body,
duration on the palate and colour
depth, while wine from
unbalanced vines had more
undesirable vegetative character
In unbalanced vines, sugar
ripening is too rapid relative to
flavour ripening. This perhaps
also applied to the development
of phenolics and mouthfeel, Dr
A trial at Geisen in Germany
looked at defoliation as a means
of balancing fr uit and vegetative
growth. Vines were defoliated
mechanically by 25 per cent or
by shoot hedging by 57pc.
Treatment delayed maturity by
between 14 and 20 days but had
no effect on titratable acidity or
pH of the wine.
Defoliation of 66pc in a trial at
Bendigo just prior to veraison
delayed sugar accumulation.
When the control reached 14 to
16 Baumé, the grapes from
treated vines were approximately
1.8 Baumé lower. The treatment
had no effect on yields but
reduced wine colour and tasting
score from 15.9 to 12.9.
Dr Dry said defoliation may
still be an option for white wines.
Anti-transpirant, in this case
Vapour Guard, applied four and
two weeks before sampling
delayed sugar development but
also reduced colour.
Anthocyanins of treated plots
averaged a colour value of 550
compared to 650 for the control
at the same Brix.
Dr Dry said some winemakers
claim increased irrigation prior to
har vest may delay ripening,
reduce Brix and lower fr uit
In a trial on cabernet sauvignon
in California irrigation was
doubled for the ripening period.
This resulted in a slight decrease
in ethanol in one out of two
season and no significant effect
on wine sensory score or wine
Australian Wine Research Institute viticulture consultant Peter Dry says the rate of sugar accumulation in grape
berries is largely determined by the ratio of leaf area to fruit weight.
Low-alcohol winemaking begins in vineyard
Leaf area, fruit weight ratio
Aim to delay sugar accumu-
Increased irrigation has no
By FRANK SMITH
Ph: 8372 5221
....Let us know
Season long weed control in vegetable
Registered trademark of AgNova Technologies Pty Ltd
Selective Weed Control in Onions and Brassicas
Links Archive Dec 2012 - Jan 2013 March 2013 Navigation Previous Page Next Page