Home Winemaking - Yeast

This one celled organism is what transforms the simple grape juice into the culture-enriching wine which has been with mankind since Biblical times. Just what is yeast, and how does it interact with the grape juice to create wine?

Yeast is a natural organism that is found in most vineyards. Early grape growers didn't know any secrets of winemaking - they simply stored the grapes after a harvest. The natural yeasts on the skins of the grapes did the rest, breaking down the sugars and oxygen present, and creating carbon dioxide and alcohol. The first grape gatherers were pleasantly surprised to find their stores of grapes and juice were now able to last longer, and tasted far better.

It was a while before the role of yeast was discovered, and wild yeasts even today play an extremely important role. In many old-country vineyards, it is still forbidden to add any extra yeasts to the wines. The native yeasts that come 'with the grapes' are stated to be the best possible for these wines. In many parts of the world, though, yeasts are experimented with, categorized, and evaluated to determine which particular yeast does the best job with a certain set of grapes.

For those wineries that wish to eliminate all natural, or "wild" yeasts so that they can use their own yeasts on the wines, sulfites are a must. Cultured yeasts can survive in up to 100 parts per million of SO2, while wild yeasts tend to tolerate much less than this. Normally the winemaker adds in the sulfites, lets it sit for a while and dissipate, and then move on with adding in the yeast they *wish* to act on the wine.

Yeast is pretty tenacious - sulfites also keep fermentation from restarting in the bottle, and helps preserve the wine.

Recommended Yeasts for Home Winemaking
Glossary of Winemaking Terms




All content on the WineIntro website is personally written by author and wine enthusiast Lisa Shea. WineIntro explores the delicious variety and beautiful history which makes up our world of wine! Lisa loves supporting local wineries and encouraging people to drink whatever they like. We all have different taste buds, and that makes our world wonderful. Always drink responsibly.