Photo: Richard Fennessy with Dr Kim Ritman, ABARES chief scientist (left) and Federal Agriculture, Fisheries and Forestry minister Joe Ludwig (right) at the ABARES Outlook 2013 conference. Image taken by Steve Keough Photography.
LAST YEAR DEPARTMENT of Agriculture and Food WA (DAFWA) research officer Richard Fennessy was awarded the $22,000 Science and Innovation Awards for Young People in Agriculture, Fisheries, Fisheries and Forestry in the category of viticulture and oenology.
Fennessy received the award based on his project proposal titled ‘Influence of climate and variety on the effectiveness of pre-fermentative cold maceration (cold soak)’.
This national award is sponsored by the Grape and Wine Research and Development Corporation (GWRDC).
Cold soak is a commonly practised winemaking technique for production of premium red wines.
The process involves the aqueous extraction, as opposed to the alcoholic extraction, of compounds from the skins into the must at low temperatures.
Wines made in this way are commonly perceived as more fruit-forward and complex, with increased colour intensity.
CHECKING TEMPERATURES ON COLD SOAK BATCHES
Research has been conducted both in Australia and overseas on the effectiveness of this technique however there is little understanding of its suitability when considering different varietals and different climatic conditions.
This project involves the three most widely-planted red varieties in Australia – Shiraz, Cabernet Sauvignon and Merlot.
For the purposes of the trial these three varieties have been sourced from both the Swan Valley and the Great Southern, representing a warm and cool climate respectively.
Each batch consisted of 90kg of fruit separated into three replicates per treatment.
Treatment 1 followed a ‘conventional’ vinification process whilst Treatment 2 followed this same process with the inclusion of a 5-day skin contact period at 6C pre-fermentation.
In late September the wines were bottled, yielding approximately eight bottles per replicate. The wines have since been analysed for pH, titratable acidity, % alcohol, residual sugar, acetic acid, colour, and free and bound sulphur dioxide.
Further detailed chemical analysis will provide the ability to discriminate samples based on their metabolomic profile, involving volatile profiling analysis by gas chromatography – mass spectrometry.
BOTTLING TRIAL WINES
The second phase of analysis on the wines was conducted on 10 December involving a panel of winemakers.
The wines were randomised and assessed ‘blind’ to eliminate any potential biases.
Each wine was assessed on colour, aroma and palate characteristics, intensities and overall quality.
Plans are to collate and analyse the data from both the chemical and sensory analysis in January.
Findings will be submitted to the GWRDC in a final report in March and results will be disseminated to industry in 2014.
LITTLE KNOWN TECHNIQUE
While literature exists on the effectiveness of cold soak as a winemaking technique, little is known about the suitability of this technique to different varieties in different regions.
Fennessy anticipates the benefits of the project to industry will be improved wine quality, colour and aroma, improved efficiency in the winery and effective management of vintages of differing temperatures.
“Mr Fennessy’s project addresses a key challenge facing all agricultural sectors, that being the ability to adapt to changing climates. His project critically addresses one of the Commonwealth’s national research priorities of an environmentally sustainable Australia,” GWRDC Executive Director Dr Stuart Thomson said.
“GWRDC supports the project’s focus on extension of research to generate improved practices in the winery that will assist businesses to be more profitable and sustainable.”