The Critical Effect of Temperature in the Fermentation of Wine

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In order to deliver its very best intoxicating flavour, the role of temperature during the winemaking process needs to be fully appreciated and carefully implemented.

In fact, of the many factors making up a fine wine, the temperature is a key element.

We kid you not; it starts as early as the harvesting stage. Some grapes are harvested early to take advantage of the chilly morning temperature. Others, similarly, requiring the right chill factor, are harvested at night. The latter is clearly vital in warmer climates.

True wine masters pay specific attention to the temperature of their precious grape harvest every step of the way.

It’s clear then, how important the role of warehouse refrigeration and HVAC specifications really is.

Wine temperature is indeed an exact science.

The Right Temperature Equals the Right Wine

The art of winemaking specifies a different wine temperature to ferment red grapes than what white wines need.

Right from the moment the freshly squeezed grapes, which is now called the ‘Must’, exit the press, they need to be cooled. Here’s where it gets personal. A vintage red wine more often needs to be cooled to 20 degrees Celsius at the exit point. The inlet temperature sits in the region of 26-28 degrees C. That is a no-no because it makes the start of fermentation difficult with a higher production of volatile acidity.

To extract the polyphenols (the tannins contributing colour and texture) for varieties like a Pinot Noir, the crushed grape temperature must be brought down to below 13 degrees C to avoid premature fermentation starting.

In white wines, low-temperature maceration enables the extraction of the aromatic compounds we taste in Sauvignon Blanc and Chardonnay. Low temperature increases the speed of sedimentation for the slow ‘debourbage’ (settling) process.

Time and wine temperature are the secrets for quality debourbage. The fermentation time for white wine is longer than that of red wine.

It’s all about balance. If the wine temperature is too hot in the fermentation process, the wine will taste as if it has been boiled, with a ‘cooked’ flavour. If the ‘Must’ ferments in too low a temperature the yeast goes dormant.

There’s no question that winemakers need to trust their cooling units to reach the ‘Goldilocks-style’ sweet spot in creating their masterpiece vintages.

Even when bottled, temperatures have a marked effect.

Fluctuating temperatures compromise the wine, which then ages prematurely. The golden rule is never leave bottled wine in a hot car. If the wine temperature rises it causes pressure in the bottle. Small amounts of its precious aroma are actually pushed out through the cork. Then when the wine is cooled again it sucks air back in through the cork. The chances that that air is pure are virtually zero. The wine will taste worse for the wear for sure.

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Enjoy The Fruits of Our Labour

Louis Pasteur said that “a meal without wine is like a day without sunshine”. We now know that to enjoy the fruits of a winemaker’s labour, wine temperature had everything to do with it. So does our handling of the wine we purchase. It is one of the most natural drinks on the planet. Europeans have a celebrated place for wine in their daily lives, so do the Jews.

It has well been said that wine is as much an intellectual pleasure as it is a sensory one. Some are satisfied just with the sensory delight that drinking great wine supplies. For others, the journey the grapes took from the region in which they were cultivated, and the country of origin with its soil properties add to the pleasure.

The amazing fact is that the ground in which the grapes grow matters. A Bordeaux red will taste completely different from a Tuscan or a Californian wine made from the same grapes, using the same techniques and the same wine temperature. It’s part of the wonder of wine that sparkling wine from the vineyards of Champagne in France tops the same cultivar and the same process in Tasmanian sparkling wine or South Africa’s sprightly tasting wines, for instance.

Clearly then, wine temperature monitoring has a critical impact on the finished product – if it finishes at all.

There is not a stage where the temperature doesn’t matter. With the enrichment of some knowledge on the scientific consideration involved in the winemaking technique, we can appreciate it more. Winemaking is an art which no civilization wants to lose.

Thanks to AHI Carrier’s investment in cooling technologies, the fruit of the vine, in our century anyway, just keeps getting better.


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