Tag Archives: wine fermentation

How is Wine Made?

Question from Roy: How is wine made? 

Reply: Hi, Roy. Thanks for writing! Your question has a, potentially, very long answer but I assume you want the short story.

For anyone who is intimidated by wine, you should know that making it is so simple it was discovered by accident. Making good wine can be quite another matter but someone, yea long ago, thought he put aside a pot of grape juice. Then, after a few days he noticed it bubbling and foaming. If he was brave enough to taste it, he found that it had a very warm, pleasant relaxing effect. So, wine was born and, as you know, goes back thousands and thousands of years. 

All you need to make wine is grape juice and yeast. The yeast is supplied, courtesy of Mother Nature. It’s like bacteria – it’s everywhere. 

The yeast feeds on the sugar in the juice setting off a chemical reaction called fermentation. The yeast converts the sugar into alcohol, carbon dioxide gas (thus the foaming) and heat. When the yeast runs out of sugar it dies or goes dormant and you have a dry (not sweet) wine. If the yeast peters out or dies early the wine will be sweet because there’s sugar left over. Continue reading


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Today’s Wine Word: Brix

This is a seasonal word, for sure. And, it should be on the rise, this week, with all this lovely, warm weather! 

Brix is a measurement of sugar. 24 degrees brix translates to 24% sugar. After such a cool summer, here, the grapes are at least two weeks behind in maturity so the brix is very much on the winemakers’ minds.

One of my clients reported 19 degrees brix a few days ago in her Petit Verdot. You can figure that the sugar will increase by about a little less than 1% a week in normal weather – whatever that means ;-). So, if she’s looking for 24 degrees brix at harvest she’s still about five weeks out. Let’s hope we don’t run into rain! 

So, winemakers check the brix with increasing frequency as the grapes ripen.

Why is sugar so important? It determines the alcohol. You can figure that a little over half the sugar will convert to alcohol during the fermentation. So, starting at 24 brix you can expect to end up with 13 or 13.5% alcohol in the finished dry wine.  Continue reading

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Wine Components: Alcohol

This excursion into the world of wine components was started by a question from an A Million Cooks listener. Jim said that, while his friends seem to pick out aromas like strawberry or vanilla, the wine just smells like wine to him!

Today: Alcohol – without it, it’s just grape juice!

During wine making, yeast cells consume the sugar in the grape juice and convert it to alcohol, carbon-dioxide gas and heat – it’s called fermentation.  When the yeast runs out of sugar it dies, or goes dormant, the fermentation ends naturally and the wine is dry (not sweet).  The higher the sugar content of the grape juice, the higher the alcohol in the wine (assuming it’s dry).  There are numerous ways to make sweet wine and, in most cases, it’s done by preventing the yeast from using up all of the sugar.  This means there’s natural sugar left over – the wine tastes sweet and the alcohol is a bit lower.

Alcohol accounts for most of the “body” or heft of the wine, along with the grape extracts. Full-bodied wines are usually at least 11.5%. That’s most of the world’s reds and a lot of the world’s Chardonnays. Light-bodied wines are, generally, less than 11%.  If you’ve never tasted a wine below 11%, they can be oh, so delightful!  Less body doesn’t necessarily translate to less flavorful wine. Continue reading

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