Yeast: Can We Live Without It?
We should thank yeast every day for what it creates for us—delicious foods like bread, cheese, and pizza. Yes, wine also needs yeast. But how does this process work?
Fermentation Process
Yeast is everywhere, from the soil of vineyards to the wine cellar. The right yeast is essential for fermentation. Fermentation is the process in which the sugars from grape juice are converted into delightful wine by yeast, bacteria, and other microorganisms. The byproducts of this process are alcohol and carbon dioxide. Additionally, special (secondary) aromas are released, giving the grape juice its unique flavors. Naturally, sulfites are also produced during this process.
The process of converting sugar into carbon dioxide also occurs in bread and pizza. In the dough, carbon dioxide forms bubbles, causing it to rise. Since alcohol is also a byproduct of the fermentation process in bread and pizza, alcohol is produced during the conversion. Yes, there is alcohol in bread! The alcohol evaporates during baking, allowing us to enjoy bread without getting drunk!
To make wine from must (grape juice), as much yeast as possible is needed. A winemaker can add extra sugars to increase the alcohol content. The more sugars there are, the more alcohol can be created as a byproduct. This process is known as chaptalization. In France, wine regions must meet a certain minimum alcohol percentage, which is why this practice is often used there.
Malolactic Conversion
Additionally, malolactic conversion can occur in the winemaking process. In this process, the winemaker converts the malic acids from the grape into lactic acids using bacteria. Since no yeast is involved, this is referred to as malolactic conversion instead of fermentation. This conversion alters the structure of the wine. In red wine, this often happens to make the wine smoother. In white wine, the malic acids are desirable, so this process occurs less frequently. The white wine takes on a buttery texture due to malo, reminiscent of a rich Chardonnay.
Champagne
The bubbles in Champagne are formed in the bottle. This is traditional and what makes Champagne, well, Champagne. All the yeast is consumed during the fermentation process, so sugar and yeast are added to the bottle for a second fermentation. This is known as liqueur de tirage. During this fermentation, the carbon dioxide cannot escape, which creates the sparkling effect in the bottle. The cooler the wine cellar, the smaller the bubbles in the Champagne. However, it should not be too cold, or fermentation will stop!
Conclusion
It’s remarkable that we need to let ingredients come into contact with yeast, allowing them to create a delightful final product for us. Without yeast, our lives would be dull without wine and bread. Yeast is just as essential as the grains in bread and the grapes in wine. When life gives you grapes, yeast will make wine for us!