In Processing

If the title of this blog caught your eye, my ploy worked. Please accept my apologies; Flash Gordon will not be featured here. Or any other superheroes, for that matter. I will however elaborate on Flash Détente and its super colour-extraction abilities.

Of late, growing interest in colour extraction (especially in California) has led to the evolution of thermovinification into Flash-Détente. During thermovinification, the temperature of crushed red grapes is raised to 60˚C for anything from one to 24 hours. Thermophiles (pardon the pun) claim that increased tannin and colour extraction is to be had with thermovinification. The logic behind this is sound, as the high temperature breaks down cell structures. This in turn releases pigments, tannins and volatile compounds in the absence of ethanol. In the absence of alcohol, chemical bonds are formed between anthocyanin pigments and other phenols which stabilizes colour in the resulting wine. Should this concept give you cold feet, you might want to opt for cold soaking. During cold soaking, crushed grapes are soaked in their own chilly juices and pumped over for a few days in an effort to extract more colour.

Not impressed yet? Enter Flash-Détente, which is basically thermovinification on steroids. Grapes are briefly (two to five minutes) heated to 85˚C and then cooled in a vacuum. Cell walls pop, juices fly and a myriad of aroma and colour compounds are released. The vaporised water (with volatile compounds trapped within) is then chilled in a condensing column, after which the winemaker is left with the decision of adding the fluid fraction back to the main tank or not. Seeing that this condensate is full of pyrazines and in the case of lower quality grapes, rot and mold aroma compounds, the winemaker usually discards the condensate. This is however a double- edged sword, as varietal and fruity aromas is also lost in the condensate. Then again, the heat application inhibits enzymes such as polyphenol oxidase and laccase, which are often present in lower quality grapes. The effect of this heat on Brettanomyces is still ambiguous. Other benefits of extracting colour earlier are; improvement of purple hues in wine, fermentation at lower temperature and usage of different yeast strains. It is also speculated that the softer and rounder tannins are better extracted with water and heat, while the harsher tannins might be brought out where ethanol is the solvent.

Many traditional winemakers believe that Flash-Détente is for higher yield facilities, where often quantity outweighs quality (sic). It has been said that the loss of varietal character often results in a one-dimensional, soulless wine. As with all other winemaking decisions, the decision to go with or without thermovinification is an important one. Current studies on thermovinification are focusing on changing tannin concentrations in must with an increase in temperature and how varietal character is affected.

With a price-tag of $2 million for a Flash-Détente set-up, winemaker experience will be key in the decision to employ this system or not. Like they say, talk is cheap.

Bernard Mocke is a technical consultant for Oenobrands.

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