The Science Behind The Numbers

by Monica Bennion on August 10, 2011

TA, RS, MLF, pH…is this the next craze in texting short code or is there something more scientific behind the abbreviations?  If you’re anything like me, when I’m drinking a good glass of my favorite wine, I’m not concerned about science, math, or even cleaning the house.   However, what about the wines that I’m not familiar with, the wines I have heard about and am dying to make my new friend?  How do I tell if they will fit in and stand out?  I could rely solely on descriptions, the awarded points or the reviews of others, or I could play detective and get to the science behind it.

Poetic verse and superfluous adjectives are a nice touch when wine tasting or reading the back of an unfamiliar bottle.  Often times they are influential enough to harness the power of suggestion.  On the other side of romantic prose and whimsical words is the geeky, cold hard science.  A science that cannot be described in words, but rather numbers, and unalterable numbers at that.  These numbers however can be even more informative than words, and can lead you to the kind of wine you’re looking for.  As for geeky, just watch “Revenge of the Nerds” and see who wins.

In this article, we will discuss a few of the structural components that make up your favorite wine, starting in the vineyard and ending in the glass.  These components include Brix, acidity and pH, malo-lactic fermentation and residual sugar.  Each of these components contributes to the taste and feel of the wine, and knowing more about the numbers is a great way to learn which new wines will become old friends.

The Brix scale is a way to measure the sugar content in grapes before harvest and during fermentation.  Monitoring the Brix level in grapes is an efficient way to determine optimal harvest time, depending on the kind of wine the winemaker wishes to make.  Grapes used for dryer white and red wines are typically harvested between 19˚ to 25˚ Brix, whereas grapes used for sweeter and dessert wines are harvested at a much higher Brix.  On average, the potential alcohol content of a wine can be determined by the degrees of Brix.  For example, a grape with a 24˚ Brix at harvest is likely to result in a wine with a 13.5%-14.5% alcohol level.  Brix is a somewhat controllable factor for the winemaker, although ideal climates and longer hang times (vine ripening) can result in optimal Brix levels.

There are many forms of acids in grapes and wine, and all of them have a direct influence on the color, balance and taste of wine as well as the growth and vitality of yeasts during fermentation and protecting the wine from unwanted bacteria.  The two most well-known acids are tartaric acid and malic acid, and are naturally produced by the grape as it develops.  The relative amount of each varies from grape type and can be changed both in the vineyard and in the barrel by environmental variables, viticulture practices and winemaking philosophies.  Both tartaric acid and malic acid contribute to the tart character found in wines.  Malic acid is most commonly described as the “tart green apple” flavor and is more often associated with white wines.  Whereas, tartaric acid represents itself in the form of “wine diamonds” and “crystals”, and is often found in both red and white wines.  Like malic acid, tartaric acid also contributes to the tartness of the wine.  Read more on Wine Diamonds here.

Another component of acidity is the Total Acidity or often seen as TA.  In the U.S., total acidity is measured assuming all the acid is tartaric.  A high TA is 1.0%, and most people would find this level of acidity too tart and too sour for consumption.  A low TA for example 0.4%, results in a flat tasting wine that is more susceptible to infection and spoilage.  On average, most wines are about 0.6% TA, with white wines usually a little higher.

Malo-lactic fermentation is an important and natural process for adjusting the acidity in wines, and usually occurs shortly after the end of the primary fermentation.  Although, naturally occurring in most red wines, many varieties of white wines are “encouraged” by the winemaker to undergo MLF.  White wines like Chardonnay tend to have a higher concentration of malic acid, and by coaxing the wine into MLF through the introduction of bacteria, the malic acid is converted to lactic acid, which results in a softer wine.  Scott does not like his white wines to go through malo-lactic fermentation, but rather prefers the crisper, more fruit forward white wines made in the Alsatian/Germanic style.  Medium to full bodied red wines benefit from MLF, and this process can result in better integration of the fruit and oak characters, contribute to the texture and mouth feel of the wine, as well as prevent a disastrous event of secondary fermentation in the bottle.

pH is directly related to the acidity, and is a way of measuring the active acidity in wine.  Although confusing at first the formula is pretty simple, the higher the pH the lower the acidity, the lower the pH, the higher the acidity.  For example, a wine with a pH of 3.0 is ten times as acidic as a wine with a pH of 4.0.  Because pH and acidity go hand in hand, if the total acidity is not available, look for the pH level.  This will allow you to determine whether a wine will be dry or sweet.  Today, most red wines in America have a pH of 3.3 to 3.6 and white wines, typically being more acidic, have a average pH level of 3.0 to 3.3.

Like acidity and pH levels, the Residual Sugar (RS) is a good way to determine whether a wine will be dry or sweet.  During the process of fermentation, the yeasts added by the winemaker metabolize sugars in the grape for energy, yielding alcohol as a byproduct.  In dry red wines, the sugar naturally produced by the grape is almost completely consumed by the yeast, whereas in sweet wines, the yeasts are killed or removed before all of the sugar is used, leaving residual sugars as a byproduct.  Dry wines are typically less than 0.5% RS, off-dry wines are usually in the 0.80%-3.0% range, and dessert wines range in the 4%-20%.

In closing, flowery descriptions and rave reviews are always a great way to gain a slight perspective on a new wine, and who knows, they may very well be spot on.  Now that we have a little more insight on the chemistry side of it, we can use these numbers to help determine the style of wine before you even pop the cork.  Visit our TRADE section and download the spec sheets to learn more about your favorite Scott Harvey and Jana Wines.

{ 2 comments… read them below or add one }

Reet January 1, 2013 at 12:53 pm

A very impressive and helpful site, with great visuals. I am looking forward to the upcoming wine resolutions. Thank you.


Jana Harvey January 2, 2013 at 9:43 am

Thanks for the feedback. We hope you find our other resolutions equally as helpful.


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