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Aust NZ Grapegrower Winemaker 525, 2007, 75 79.pdf


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winemaking
(CMA) content (mg/L) was estimated using
the following formula: 203(A520 -CDRSO2).
Percent of coloured monomeric anthocyanins
out of the total monomeric anthocyanins
(CMATMA) was calculated by dividing CMA
by TMA.
Winemaking Details. A summary of
the vinification protocols for the Merlot and
Cabernet Sauvignon wines is given in Table 1.
The full-scale commercial micro-oxygenation
treatments and control wines for each variety
were harvested, crushed, pressed, tanked, and
barrelled on the same dates, and were treated
equivalently in all regards with the exception
of exposure to micro-oxygenation.
In brief, Vitis vinifera L. cv. Merlot grapes
were harvested by hand-picking between 2630 September, 2006, were crushed/destemmed
60% whole on 3 October, and fermented for 14
days until pressing of the grapes on 17 October.
The control Merlot wine was then placed in a
stainless steel tank until 8 November (a 22 day
period), at which point it was barrelled. The
treatment Merlot wine was placed in a 4550L
stainless steel tank on 17 October and exposed
to a micro-oxygenation regime at dosing rates
between 24 and 34mL/L/month for a 15 day
period until 1 November, after which the
treatment wine was held in the stainless steel
tank until barrelling on 8 November.
Similarly, Vitis vinifera L. cv. Cabernet
Sauvignon grapes were harvested by handpicking on 26-27 October, 2006, were
immediately crushed/destemmed 60% whole,
and fermented for 12 days until pressing of the
grapes on 8 November. The control Cabernet
Sauvignon wine was then placed in a stainless
steel tank until 4 December (a 26 day period),
at which point it was barrelled. The treatment
Cabernet Sauvignon wine was placed in a

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Micro-oxygenation of the two red wine
varieties (Merlot and Cabernet Sauvignon)
resulted in different colour characteristics
compared to the control wines (Figure 1). In
general, the Cabernet Sauvignon wines were
slower to respond to micro-oxygenation than
their Merlot counterparts, requiring between
10 and 30 days longer to show the effects of
treatment.
After 181 days following the press, the
micro-oxygenated Merlot trials had higher CI,
TCP, WC, CDRSO2, CDNRSO2, CAW, WA,
CMA, and CMATMA, and lower percentage
of yellow relative to the non-micro-oxygenated
control wines. There was no significant
difference in the percentage of red or blue, tint,
brilliance, I280, and TMA between treatment
and control wines after the 181 day aging period.
The results suggested that micro-oxygenation
does not affect the total quantity of phenolics
in wine (as inferred by the I280 value), but
alters the partitioning of these compounds
between more polymerised, stable, or coloured
forms. The 181 day aged micro-oxygenated and
control Merlot wines had lower CI, percentage
of red, brilliance, TCP, WC, CDNRSO2, TMA,
CMA, and CMATMA, and higher percentage
of yellow and blue, tint, CAW, WA, and I280
relative to samples collected immediately after
the press. The micro-oxygenated Merlot wine
had a higher CDRSO2 than the aged control
and the just-pressed samples, and there was
no significant difference in CDRSO2 between
the aged control and just-pressed samples.
Added colour stability is a perceived benefit
of micro-oxygenation, and is supported by the
Merlot trials.
At 159 days following the press, the microoxygenated Cabernet Sauvignon trials had
higher CI, % of yellow and blue, tint, CDRSO2,
CAW, and lower percentage of red, brilliance,
and CMA relative to the control wines.
There was no difference in the WC, TCP,
WA, CDNRSO2, I280, TMA, or CMATMA
2.0

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3.0

MOX (day 181)

1.0

0.0
300

just pressed

1.0
NOX (day 181)

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MOX (day 159)

2.0

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between the micro-oxygenated and control
Cabernet Sauvignon wines. The 159 day
aged micro-oxygenated and control Cabernet
Sauvignon wines had lower CI, percentage of
red, brilliance, WC, TMA, CMA, CMATMA,
and higher percentage of yellow and blue,
tint, CDRSO2, and CAW relative to samples
collected immediately after the press. There
was no significant difference in TCP, I280,
or CMATMA between either the microoxygenated or control wines after 159 days of
aging and samples collected immediately after
the press. The micro-oxygenated Cabernet
Sauvignon wine had a lower CDNRSO2 and
TMA, and a higher WA, than the just-pressed
sample, and there was no difference in these
variables between the aged treatments and
controls.
Although the Merlot and Cabernet wines
(both micro-oxygenated and controls) had
similar changes in their colour properties
over the six-month aging period, there were
several notable different effects due to microoxygenation between the two varieties. Microoxygenated Merlot wines had a lower percentage
of yellow and no significant difference in
percentage of blue relative to aged controls.
In contrast, the micro-oxygenated Cabernet
Sauvignon had a higher percentage of yellow
and blue, and a lower percentage of red,
relative to the control wines. These differences
led to micro-oxygenation increasing the tint
and decreasing the brilliance of the Cabernet
Sauvignon wines, whereas no difference
was observed for these variables between
treatments and controls in the Merlot wines.
Micro-oxygenation led to an increase in the
CMA in the Merlot wines, and the opposite
influence in the Cabernet Sauvignon. Microoxygenation increased the TCP and CMATMA
relative to the controls for the Merlot wines,
but no significant treatment effects on these
variables were observed for the Cabernet
Sauvignon trials. Significant varietal effects on
all variables were observed, with the exception
of percentage of blue and WA.
A multivariate technique (principal
components analysis, or PCA) was also applied
to the colour dataset on the MOX and control
wines to further distinguish the treatment
effects within and between varieties. PCA of
the colour characteristics explained 84.5%
of the variation in the data in the first two

(a) Merlot

Absorbance

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wa t e

Do
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TOTAL CONCEPT

Findings

ve

By

7100L stainless steel tank on 8 November
and exposed to a micro-oxygenation regime
at dosing rates between two and 44mL/L/
month for a 14 day period until 22 November,
after which the treatment wine was held in
the stainless steel tank until barrelling on 4
December.

400

500

NOX (day 159)
600

700

800

0.0
300

400

500

600

700

800

Wavelength (nm)

Fig. 1. Ultraviolet-visible spectra for must immediately after pressing and the micro-oxygenated (MOX)
and non-micro-oxygenated controls (NOX) for the Merlot (a) and Cabernet Sauvignon (b) wines at 181
days and 159 days, respectively.

76 The Australian & New Zealand Grapegrower & Winemaker

www.winebiz.com.au

October 2007