This is an in-depth article for geeks with an itch for the nitty gritty details of wine. If you’re one who is as described, you’ve certainly come across wine technical data before. So, what can we learn by looking at wine tech sheets?
This topic is actually profoundly deep as you can observe in the sources below, but the basics can be grasped by anyone–that is to say, anyone who wants to know them!
Most of us experts will agree that technical data doesn’t define the quality of a wine, but it can help you understand a particular wine, especially when comparing different vintages.
Understanding Wine Tech Sheets
ACIDITY: The acidity level tells us the concentration of acids present in wine. 2 g/l is very low acidity and the wine will taste flat and 10 g/l is high and very sour. Typically wines range between 4 and 8.
pH: The pH level tells us how intense the acids taste. The relationship is inverse so the lower the pH number, the more intense the acids present in the wine will taste. The number is logarithmic, so a pH of 3 has 10 times more acidity than a pH of 4.
ABV: This is the percentage of alcohol in wine. Most wines range from 10–15% alcohol although there are several specialty wines, such as Moscato d’Asti (very low) or Port (very high), at the extremities. You can check out a cool infographic on alcohol in wine for more information.
Aging/Maturation: This tells us the methodology the winemaker’s use to age the wines, including whether wines were aged in oak and for how long. Some will also tell us the type of oak (French, Hungarian or American) and how new they are (new vs. used or “neutral”). Aging wine is more common with red wines than white wines.
Malolactic Fermentation (MLF): The answer is usually a “yes” or a “no,” and it tells us whether or not the winemaker chose to convert a tart-tasting acid, malic acid, into a smoother, creamier-tasting acid called lactic acid. Nearly all red wines undergo MLF, and much less so for white wines. A white wine that commonly undergoes MLF is Chardonnay.
RS: This stands for Residual Sugar and is the measure of sweetness in wine. Typically, wines with less than 10 g/L are considered dry. Many dry wines have none at all. Check out this chart that compares wine sweetness.
Brix: This is a measurement of the percentage of sugar in the grape juice at harvest. So, 24 Brix is 24% sweetness. Brix tells us how ripe and sweet the grapes were when they were picked.
Acidity vs pH in Wine
We talk a lot about the acidity of wine on the blog more as a reference to how acidic a wine tastes which, as it happens, is sometimes in reference to pH versus total acidity. The topic is actually quite complex (if you want to get into it, see sources below). Fortunately, Dr. Waterhouse at UC Davis has a beautiful explanation:
“The basic difference is intensity vs amount. pH is an intensity type of measure, while TA is a quantity. An example of this type is hot water. The intensity is the temperature and the amount would be the volume. So, sourness in the mouth is related to both, just as a sensation of heat in the mouth would be related to the temperature of hot water and the amount. Within a reasonable range, the sensation of heat depends on both. In wine, the TA over its normal range is typically more powerful than pH, but at the extremes pH does have an effect.
For instance CA wines are usually in a small range of pH, say 3.5-3.9, with TA’s’ near 6 g/L (tartaric acid equivalent). If the TA is 8, the wine will taste quite tart, and it is 4, the wine will taste quite flat. On the other hand, with a constant TA of 6, it will take change to about 3.3 or lower for a wine to taste distinctly tart, and at 3.0 it will surely be sour!!”Dr. Andrew Waterhouse, Professor of Enology, UC Davis
Aging wine changes numerous phenolic qualities of a wine, particularly the taste and quality of tannin, which is why red wines tend to receive more aging than white wines. On the same note, white wines are typically made to highlight their floral aromas and acidity (ahem… “tartness”), and these traits are reduced with aging.
- Stainless Steel Aging: Stainless steel tanks are essentially anaerobic chambers that inhibit the ingress of oxygen into a wine. Stainless steel tanks (as well as inert concrete) are used to preserve acidity and floral flavors, which is why they are popular with white wines including Chablis (unoaked Chardonnay) and Sauvignon Blanc. Stainless steel and concrete are also used on bold tannic red wines to smooth-out tannins while maintaining the wine’s floral aromas and acidity. A good example of this would be a Cru Rhône (such as Vacqueyras) or Châteauneuf-du-Pape red wine which often use a blend of neutral oak-aged and tank-aged wines for balance.
- Oak Aging: Oak barrels, on the other hand, are porous vessels that slowly allow the ingress of oxygen into the wine, reducing the harsh taste of tannin. Besides the effects of oxygen, oak aging is used for several other purposes:
- New oak (especially toasted oak barrels) impart flavor compounds including Diacetyl and Vanillan which add buttery, caramelly, chocolatey and vanilla-y flavors to wine. The smaller the barrel used in aging, the more oak flavors are added.
- Oak barrels are usually when MLF occurs.
- Wines slowly evaporate while aging in porous oak (a process called the “Angel’s Share”) and the remaining wine will have a higher alcohol level; making it taste richer.
How Wine Making Processes Affect Wine
Six winemaking processes and how they affect the taste of wine.
Relationship between Total acidity and pH. UC Davis
More information about acidity in wine. Missouri Grape & Wine Institute
A fun way to look at Petite Sirah with tech sheets by Twisted Oak
Detailed information about how oak aging affects wine. Iowa State University