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Can technology do more to improve wine?

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By Richard Mills, RIM@foss.dk
Analytical technology introduced to the wine industry over 14 years ago is making a major difference to the way wine is produced today. And according to speakers at the FOSS wine conference in Bordeaux earlier this year there's a lot more in store for the innovative wine industry.

In his opening presentation, FOSS France general manager, Emmanuel Debraize outlined the development of wine analysis since the introduction of Fourier Transform Infrared (FTIR) analytical technology with the original WineScan instrument in 1999 to the groundbreaking WineScan S02 in 2012. Today, over 1000 FOSS analytical units are in use around the world. 

Testing polyphenolic compounds with FTIR gives more insight into grape maturity
The FTIR technology behind rapid analytical solutions like the WineScan already delivers a wealth of data helping growers and winemakers to improve both quality and economy, but more and new potential sources of information in the infrared spectrum are still being discovered. One of the more recent developments is the ability to test the polyphenol maturity of grapes that affects the taste, colour and sensation of the wine in the mouth.

Professor Tesseidre, ISVV, Université de Bordeaux, France, discussed the different Phenolic compounds in the skin and pulp of grapes and reported a strong interest in the so-called ‘Glories Index’ test developed for the WineScan as a much quicker alternative to manual chemical methods. Comparisons of the two methods are favourable, but Tesseidre stressed the need for further development. 
“There is a correlation between predicted calibration and manual analysis improving for some compounds such as ApH1 and ApH3.2 while the calibration needs to take into account tannins quality and concentration as well as anthocyans for the future,” he said. 

 

“Very quickly you get a 
vision of your vinification”

Bertrand Bourdil, UDP Saint-Emilion

 

It is also necessary to use appropriate berry sampling that takes into account the asynchrony of maturity across the sample, the use of same type of crushing to reduce variability.

The practical application of the rapid FTIR Glories index test was explained by the next speaker, Bertrand Bourdil, UDP Saint-Emilion, France who put the use of the polyphenol data in context with other FTIR test data. 

An early adopter of FTIR, Bourdil said: “When we first bought the equipment, we saw very quickly the whole potential. But it was not enough, especially in area of St Emillion where we have a lot of merlot grapes and the harvesting window is very narrow.” The Glories analysis with FOSS equipment is important with up to 200 tests per day helping to decide harvest dates and to decide payment to growers. In comparison, around 12 tests per day are possible with the manual method of the Glories index. 

Emphasising the need to exploit the polyphenolic quality through field management such as leaf removal from the vines, Bourdil said: “The potential of Polyphenols is essential. But it involves work for growers and it is necessary to pay for this work.” Two parameters ApH1 and ApH3.2 are used as payment parameters. ApH1 is used to indicate concentration and ApH3.2 for the maturity. The information is also used by the winemaker to decide vinification for example the tank destination for the grapes.  

Combining the polyphenolic quality tests with the other WineScan tests gives more control throughout the process with one analytical unit covering multiple uses including tracking maturities, sanitary index, controlling vinification and adjustment accordingly, supplementing the tasting process and predicting the ageing process. 
“Very quickly you get a vision of your vinification,” said Bourdil.

 

Barrels of Wine

Can a machine assess aromatic quality?
Continuing the FTIR theme, Eric Serrano, IFV Sud-Ouest, L’isle s/Tarn, France presented a new approach for evaluation of Grape aromatic potential by FTIR. The new test is helping to address a commonly-asked question: what is the aromatic and tannin quality of my must? 

He presented a study to examine the application potential of FTIR involving collaboration with wine producers in the South West of France using a PLS-Discriminant calibration model for the FOSS WineScan. The objective was to predict the aromatic and tannins quality of white and black grape varieties with a single FTIR measurement on arrival at the winery or five days before harvest. The parameters measured with the FTIR are correlated with 3 MH, A 3MH and IBMP corresponding to aromatic tasting for thiols, green pepper, violet and red fruit and tannin tasting for quantity and green, dry and good tannins. A cross-validation of results over three years from 2009 – 2011 showed an average performance of around 72% for five main grape varieties, which means that two out of three trucks can be well classified. The test is now being used by wineries primarily to segregate grapes for appropriate processing and economic gain. 

Infrared promoting agro-oenology
Marc Dubernet, Laboratoires Dubernet, Narbonne, France described how analytical data has brought the previously distinct worlds of agronomy and oenology closer together to the benefit of wine quality. An example is the mineral balance of the must and wine and the soil and in the vine important for alcoholic and malolactic fermentation, flavour potential, alcoholic potential and acidity balance. “From the soil to the wine, there are a lot of important things to know to understand the terroir personality of the wine,” he said. 

An interesting example is the evolution of alcohol content in red wine from the Languedoc region over the last 30 years from around 11.5% in 1984 to 13.5% today. The initial increase was due mainly to the introduction of new grape varieties, but from 1997, a sharper increase in alchohol content occurred due to climate change until there was a stabilisation in 2010 with a succession of colder springs. The same trend is seen in pH and acidity values, but with an opposite decreasing effect. The availability of FTIR analytical technology allows winemakers to track these sorts of events to see what is happening with the grapes before they arrive at the weighbridge. Another example is the ability to measure key parameters such as total nutritive nitrogen and potassium. The cumulative data gives insight into the evolution of grapes over time such as the potassium content of vine leaves during the high-quality 2011 vintage compared to less successful vintages in 2012 and 2013 which were affected by the cold spring. “When you have the possibility to see the situation with grapes very early on, you can make some corrections directly on the vine, but also prepare for what you will have to do in the oenological process to correct the problem,” said Dubernet. 

 

Wine conference 

Tartaric stability and anticounterfeiting 
Other presentations included a look at how FTIR can be used to predict the tartaric instability of wines. “Tartaric instability represents one of the biggest problems linked to the sale of bottled wines,” said Dr. Mario Malcarne. In particular, resulting precipitation in the bottle can lead non-experts to suspect problems with quality or the healthiness of the product. A study on the possible use of FTIR has been conducted with promising results. A paper entitled: ‘Use of Fourier Transform Infrared spectroscopy to create models for forecasting the tartaric stability of wines’ has been published by Elsevier. The paper describes a study based on 536 samples of Italian red and white wines. 

While FTIR dominated discussions at the conference, other technologies can also add value to wine production, for instance, in fighting the growing challenge of counterfeiting. Pizio Roberta from Erinformatica SRL, Italy presented a double QR code labelling system that can improve logistics and avoid poor quality wine being sold as respected wine. In a recent case in Siena, police seized more than 30 thousand bottles of poor quality wine labelled as Brunello of Montalcino, Chianti and others.

 

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