View Full Version : A Day in the Life of a Red Fermenter

Mick Pacholli
13th July 2013, 03:11 PM
We’re now well into the 2013 vintage with grapes coming in thick and fast. And while they may sit idle for 9 months of the year, this is the time when our red fermenters pull up their socks and go all out, putting in all-nighter after all-nighter until the job’s all done and the wine’s all made. Little wonder they need most of the year off after the efforts they put in at vintage time. So what is a red fermenter? *What does it do, and why is it only for reds?
http://www.tooraktimes.com.au/~/media/Wolf Blass/Images/From Our Winery Blog/Fermenter Shed.ashxAfter the grapes are harvested, the first step in making wine is to crush them. In the crusher, the grapes are fed through rollers, which gently break apart the skins, releasing the juice inside. And it’s from this point onwards that whites and reds diverge and go their separate ways when it comes to how they’re made.White grapes go immediately to the press, where the juice is pressed from the skins for fermentation as a liquid. But for reds, things take a slightly different turn. As the colour of almost all red grapes is found in the skins, steeping the juice in contact with the skins for a time is necessary to give red wines their magnificent colour, flavour and structure. The crushed grapes are called “must” and after crushing, the must is sent to a red fermenter, a specialised vessel for fermenting red wine, which can be as simple as an open tub or as complex as a rotary fermenter, a closed vessel which turns somewhat like a concrete mixer.What is Fermentation?In simple terms, fermentation takes place when wine yeasts convert the sugars in grape juice into alcohol and carbon dioxide. Fermentation is the single most important stage in making red wines, as not only does this simple conversion take place to turn grape juice into wine, but all sorts of other alchemical magic is going on around it, bringing about something so intriguing and delicious that poets will write verses of praise to this glorious drop. Along with the extraction of colour from the skins, during the fermentation process flavours and tannins are also extracted from the skins and seeds. These provide the wine with structure, mouthfeel, balance and longevity, not to mention deliciousness.Carbon dioxide gas is a by-product of yeast fermentation, and as this is released throughout the fermentation, bubbles of gas float the skins to the surface of the must, forming a dense “cap” and separating them from the juice below. In order to get the best extraction of colour and tannin, the skins need to be continually resubmerged in the juice. This is achieved by either plunging the cap back under the juice, or by pumping juice from the bottom of the fermenter back over the top of the skins, allowing it to gush back over the cap as you can see in the photograph below. With rotary fermenters, the entire closed vessel is turned to bring the skins back in contact with the juice. In all cases the cap is re-moistened and broken up, and better contact with the juice allows for improved extraction of those all-important colours, flavours and tannins.
http://www.tooraktimes.com.au/~/media/Wolf Blass/Images/From Our Winery Blog/Red Fermenter.ashxStyle DecisionsThe skins can stay in contact with the juice for anywhere from several days to a number of weeks depending on the style of wine being made. At the start of fermentation more water-soluble tannins and flavours are extracted, and as the alcohol level rises there is extraction of alcohol-soluble elements, each of which lend the wine their own unique attributes, allowing the winemakers to decide what is best suited to the style they are creating.Less time on skins will generally result in softer, rounder, more approachable wine styles, like our Yellow (http://www.wolfblasswines.com/en/Our-Wines/Yellow-Label.aspx) and Red (http://www.wolfblasswines.com/en/Our-Wines/Red-Label.aspx) Labels, while greater time on skins will allow for more, and different, tannin extraction creating a more structural wine with great palate length, like our Platinum (http://www.wolfblasswines.com/en/Our-Wines/Platinum-Label.aspx) and Gold (http://www.wolfblasswines.com/en/Our-Wines/Gold-Label.aspx) Label wines. Our Black (http://www.wolfblasswines.com/en/Our-Wines/Black-Label.aspx) and Grey (http://www.wolfblasswines.com/en/Our-Wines/Grey-Label.aspx) Label wines are made to a different style again, being pressed off skins while still retaining a touch of sugar, then allowed to finish their fermentation in oak barrels.The winemakers taste the ferments daily to assess their development and decide how they would like the ferments to progress. Temperature has a dramatic impact on the rate of fermentation and may be tweaked each day or so to provide the most appropriate outcome. Warmer temperatures will speed up the fermentation and allow for rapid extraction of fruit flavours and tannins, but too warm and the delicate fruit flavours will be blown off. Cooler temperatures will slow the fermentation allowing for a deliberate build of tannins and retention of bright fruit flavours. Again, depending on the style, most of our ferments will start off warm to break the cell walls and allow all the flavour, colour and tannin molecules to spill out. They are then cooled down to control the fermentation and allow for longer, slower extraction.When fermentation is complete to the style intended by the winemaker, the wines are pressed from the skins and voilą – red wine has come to life. Clever little fermenters!

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