How does grape juice ferment into wine

Since not all yeasts are suitable for making wine, many wineries employ sulfites to suppress the activity of wild yeasts before fermentation, followed by inoculation with a commercially developed, cultured strain of Saccharomyces yeast.

At 2Hawk, we prefer to take a gentler approach, encouraging the growth of desirable yeast found in our vineyard. These naturally occurring yeasts contribute a subtle, nuanced complexity to the finished wine that reflects the unique character of the Rogue Valley and our vineyard in particular.

As fermentation progresses, some species of yeast begin to rapidly convert the natural sugars present in the must into carbon dioxide and ethanol, or ethyl alcohol. Produced as a defense mechanism, few species of yeast can tolerate even moderate levels of ethanol. As ethanol levels continue to rise, one strain— Saccharomyces— emerges as the victor of this fierce competition and embarks on fermenting the wine to dryness.

Various types of yeast make their own individual contributions to a fermenting wine, but fermentation is influenced by other factors as well. The higher the initial sugar content of the must, the more alcohol will be present in the finished wine—if allowed to ferment to dryness. More alcohol means a tougher job for the yeast, making monitoring yeast health important: unhealthy, stressed yeast are more likely to produce undesirable flavor and aroma compounds.

Fermentation temperature is also crucial. If temperatures are too low, however, yeast work slowly—or they may have difficulty fermenting all of the sugar. Higher temperatures allow for better grape skin tannin extraction but tend to drive off fruity flavors and aromas. If temperatures are too high, yeast may work at a frantic pace, producing undesirable flavors and aromas along the way.

Finding the right fermentation temperature is all about balance. Red wines are typically fermented at the warmer end of the spectrum—between 70 and 85 degrees Fahrenheit—to take advantage of better tannin extraction. White wines are more often fermented at the cooler end of the spectrum, around 45 to 60 degrees Fahrenheit.

Because fermentation is an exothermic process i. At 2Hawk, we tend toward small batches, allowing for better passive cooling and reduced needs for active temperature control systems. In a winery, fermentation occurs in a fermentation vessel, where yeast is allowed to complete its work. Different fermentation vessels can influence how fermentation proceeds as well as the finished wine. Oak, for example, allows for gradual oxidation of the juice and wine, while the wood usually softens the impact of tannins and acid, resulting in a rounder wine with a distinct character.

Stainless steel is highly nonreactive, making for bright, clean, and crisper wines. Concrete fermentation vessels can leave behind a subtle mineral character in wines while permitting a little desirable oxidation. Clay vessels, a traditional choice making a comeback in recent years, enable some oxidation while being neutral or slightly earthy in terms of flavor contributions.

The more porous the vessel, the more oxidative the conditions. Smaller fermentation vessels have more surface area for a given mass, meaning they can more easily shed excess heat from fermentation.

Vessels with a rounder shape aid convection currents in the fermenting wine, facilitating fermentation by keeping temperatures uniform and yeast in suspension. Most of the time, fermentation is complete when yeast have consumed all the sugar they can, usually meaning the wine is fermented to dryness.

The presence of yeast lees can have a profound effect on the aroma, flavor, and texture of the wine as it ages. We hope you enjoyed getting an inside look at this complex but essential aspect of the winemaking process. For a more general overview of winemaking, including what happens before and after fermentation, take a look at our earlier blog post, How is Wine Made?

Can we answer any other questions you have about making or tasting wine? Please let us know! I left the batch undisturbed as per the kit instructions. However, I did check for expansion. There was hardly any. Should I let it work for a couple more days? The temperature is still very cold. Most wine yeast will work very very slowly, if at all, in that temperature range. Make sure you have a means to release pressure from the fermenter aside from manual burping, as a vigorous fermentation can easily cause sealed containers to explode.

There is the possibility of a second fermentation which, unlike the first one, is undertaken by separating the solid matter from the liquid.

This second fermentation is more common in the processes for making red wine and is what helps to soften and give complexity to the purely fermentative flavours and aromas. In this fermentation, the transformation of a strong tasting acid malic acid takes place, changing it into a milder one lactic acid. Now that you know more about the winemaking process, the next question you may wonder is why it is fermented; the answer to this is that thanks to the action of certain yeasts, the sugar can be transformed into ethanol.

This transformation takes place through the metabolic process caused by the yeast , which feeds on the glucose and fructose existing in the grape. Through its metabolic action, mainly ethanol is obtained, although carbon dioxide is also released. For this reason, in its first fermentation the wine accumulates foam in its top layers and looks like it is boiling.

Together with the alcoholic volume, the wine takes on its bouquet and aroma , as well as body, smoothness and taste. As you discovered at the beginning, the different types of fermentation depend on the kind of wine you want to make. Next, we are going to explain the types of fermentation that exist, going deeper into the characteristics and the effects achieved with each one. This is the first step which, as you have seen, turns the must into wine.

A few producers still ferment their wines in oak casks, tuns, etc but most prefer thermostatically controlled stainless-steel vats.

Capacity ranges from 50 to several hundred hectolitres and the content of each vat is carefully labelled by cru, pressing fraction, varietal and vintage. The grape musts may also be chaptalized after racking enriched with sugar so as to obtain 11 per cent alcohol by volume by the end of fermentation. The general recommendation for fermenting wine in terms of temperature is to keep the temperature between 70F and 75F.

Answer: Total fermentation time is typically 4 weeks, but this varies with temperature and juice sugar content. Older wines will taste less like fruit and more like stuff other than fruit.

Originally Answered: What does wine over years old taste like? The answer of Bart Loesley is partly correct. The difference between grapes and wine is that a yeast consumed the sugar in the grapes and produced alcohol and carbon dioxide. Now, you can sometimes make wine without adding any yeast.

Most winemakers prefer to inoculate with a commercial yeast, which is much more predictable. So the short answer to your question is no, only some strains of yeast can be used to make wine. Bread yeast will typically stop working at about 10 percent alcohol, lower than most wines. And a tired yeast struggling to ferment can start to create some off-putting flavors and aromas.