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.