Brix & Alcohol
To my knowledge there is no numeric measurement for fruit forwardness in a wine – you just have to taste it. Sometimes people will use the term “extraction” to try to communicate fruit forwardness: when a wine is called extracted, it is usually referring to richness (think of a sauce reduction in cooking – more flavor per volume), but fruit forwardness often plays a role. I said in the last blog that sweetness/residual sugar is measured in grams/liter, but very few winemakers share this number with the public. I don’t know why they don’t, but they should. I checked many wine spec sheets in preparing this blog, and I only found one that included residual sugar. It was an Oregon Pinot Gris that had RS of 9.6g/l – towards the highest (sweetest) end of what would be called a “dry” wine. But because of the wine’s high acidity it did not taste as sweet as I expected.
A different measure of sweetness, however, is commonly shared on most wines’ spec sheets, degrees Brix – and it refers to the sweetness of the grapes at harvest, not of the finished wine. Each degree of Brix means there is 1 gram of sugar for every 100 grams of liquid (grape juice), so it is similar to a percent. At this point it is important to remember that fermentation is the chemical process where sugar is turned into alcohol by yeasts. So Brix, or sugar at harvest, is the beginning inventory that ends up as a wine’s alcohol plus its final residual sugar. One of the most important decisions a winemaker makes is when to pick the grapes. And the grapes’ Brix is one of the main qualities monitored in determining the right time. The longer the hang time, the riper the grape, and the higher the sugar (Brix) – and usually, the higher the sugar, the higher the resulting alcohol. So if a winemaker wants to make a dry wine (say with less than 5g/l RS), and have a target alcohol of 15%, he will pick the grapes at around 27 Brix (later); if the target alcohol is 12% he would pick the grapes at around 22 Brix (sooner). There are other qualities in grapes that are monitored to determine when to pick, and if the sun, moon, and stars come together, these qualities plus the Brix are optimal at the same time. Phenolics come into play here, but we will save this discussion for another blog.
Now what if the weather is cold one year and the grapes never get to a high enough Brix? In certain parts of the world where this occurs fairly regularly, like some regions of France, Germany, and the U.S., it is permitted to add some sugar to the unfermented grape must (juice), which is called Chaptalization. This is not to increase a wine’s sweetness, but to get a higher level of resulting alcohol. Chaptalization is prohibited, however, in Argentina, Australia, Austria, California, Italy, and South Africa.
As an aside, have you ever wondered why only grapes are used to make fine wine and not other fruit? The reason is that only grapes have a high enough level of natural sugar (and liquid) to complete the fermentation process without adding outside sugar. And if you have ever eaten them, wine grapes are much sweeter and richer than the Thompson seedless grapes you get to eat at home. And the seed content of wine grapes is too high to market them as an edible fruit.
One last story. A few years ago I wanted to decrease my consumption of alcohol, so I started to look for wines with lower levels of alcohol. I had heard that many German Rieslings had alcohol levels from 6%-9% (compared to the 13%-16% of most California wines), and, since I am not interested in drinking sweet wines on a daily basis, I was glad to discover that there were some very dry German Rieslings. But my quest was frustrated when I found out that the dry Rieslings had 12% or more alcohol. To become dry, the fermentation had to continue until almost all of the sugar was converted into alcohol; to keep the alcohol low, the fermentation had to be stopped well before all of the sugar was converted – leaving it quite sweet.
High alcohol has become a big problem for winemakers, especially in California. Longer hang times, warmer summers, more efficient yeasts can lead to levels above 16%. There are ways to intervene to remove alcohol from finished wine, such as reverse osmosis and the use of centrifuges. But with these practices we are getting into the area of wine manipulation, which is often frowned upon. This too will be the subject of a future discussion.