Wine chemistry insights


# **Wine chemistry insights** **We decided to run some of our wines against each other in the lab to see what the lab analysis data would show.** But before we show you the results, we need to introduce some common measurements in wine chemistry: **Ethanol:** The alcohol level of the wine measured as ABV % (alcohol by volume). **pH:** A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral. **TA:** Titratable acid (TA) is a measure of the sum of all the organic acids in juice or wine. **VA:** Volatile acidity (VA) is a measure of the wine's volatile (or gaseous) acids. The primary volatile acid in wine is acetic acid, which is also the primary acid associated with the smell and taste of vinegar. **Malic:** Malic acid (after the Latin word for Apple: malum) is one of the primary acids in wine. It is also one of the "sharper" acids as you might imagine when you think about biting into an unripe green apple. During malolactic fermentation, bacteria convert the stronger malic acid into the softer lactic acid. **Lactic:** Lactic acid is often associated with milky flavors in wine and is the primary acid in yoghurt and sauerkraut. It is produced during winemaking by lactic acid bacteria (LAB) such as Oenococcus, Pediococcus and Lactobacillus. **Astringency:** Astringency is a wine tasting term that applies to the tactile feeling of the wine in your mouth. It refers to the dry, puckering or rough feeling created in the mouth by the interaction of phenolics with saliva. It is often confused with bitterness. **Glycerol:** Glycerol is a viscous, colorless and odorless liquid and gives wine a fuller, more pleasant texture.  **RS:** Residual Sugar (or RS) is from natural grape sugars leftover in a wine after the alcoholic fermentation finishes. It’s measured in grams per liter. More RS means a sweeter wine, i.e. a wine that is not fully fermented to dryness. **MCP Tannin:** Methyl cellulose precipitable (MCP) tannin is a measurement of the tannin concentration in red wines. After having turned you into half a wine chemist, we can now continue with the lab analysis. **2018 The Commission versus 2018 The Ringer** Both of these outstanding wines were sourced from an ultra-premium estate in Pritchard Hill, Napa Valley associated over the years with winemakers Michel Rolland, Helen Turley and Helen Keplinger making the likely source winery pretty obvious. This is from a mountain estate that the Wine Advocate called, “without question one of the most spectacular vineyards in Napa Valley.” Vinous critic Antonio Galloni seconded, “I don’t see any reason why the Cabernets that emerge from this property shouldn’t be among the top five to ten wines in the valley each and every year.” And Robert Parker has called them “some of the most singular and prodigious Cabernet Sauvignons of Napa Valley”, and “one of the wines that redefines greatness in Cabernet Sauvignon”. When we acquired the wines we were told that they have the same base juice and the same oak treatment and that the differences relate to the fining agents used to finish the wine. Fining is a bit like adjusting a digital photography in that you can dial up or down certain attributes including color, astringency, acidity and sweetness in the case of wine. Below is what the base chemistry analysis tells us when we compare these two wines. subimage1 As you can see, both of these wines are "BIG" in that they go on the extremes on pretty much all dials. The lab analysis also confirms that these two wines are indeed very similar as could have been expected given that they come from the same source. The one notable difference is a higher proportion of malic acid in The Ringer. The lab analysis picked up that 2018 The Commission appears to have been subject to a more gentle fining treatment with slightly higher concentrations of oak markers as well as treatment with Velcorin, a compound used to inhibit the growth of spoilage micro organisms. In terms of flavor profiles, we have the below for the two wines: subimage2 The two wines are very similar in terms of astringency, boldness and mouthfeel. The differences are that 2018 The Commission is slightly fruitier while 2018 The Ringer is more pungent. But in the grand scheme of things, these two wines are fairly close to each other which is good news for those who missed acquiring 2018 The Commission when our bottles sold out. This gives you another chance to pick up a closely related wine before this one too sells out. **2018 Radio Silence versus 2018 Yesterday Reserve** Next, let's turn our attention to two other siblings, from backdoor barrels acquired from an ultra premium Oakville Estate that has been in the same family for a long-time. The below is what the lab analysis tells us about those two wines: subimage3 Once again, the lab analysis suggests that we are indeed dealing with two closely related wines. 2018 Yesterday Reserve has a bit more Residual Sugar than Radio Silence which might contribute to a sensation of being slightly sweeter. On the other hand, 2018 Radio Silence scores higher in terms of Titratable Acidity and Volatile Acidity - that is two common wine chemistry measurements for acidity. Next let's turn to a comparison of the flavor profiles of the two siblings: subimage4 And yet again we find two close siblings here with the only real difference in markers being that 2018 Radio Silence scores slightly higher in terms of pungency. So overall, the lab analysis has confirmed the similarities between the two “sibling wines”. Let's next do a cross comparison for the fun of it. **2018 Radio Silence versus 2018 The Ringer** Below is what we find when we compare 2018 Radio Silence with 2018 The Ringer. subimage5   Here we begin to see greater differences in the spider diagram as could be expected from wines coming from two completely different estates - Oakville versus Pritchard Hill. We see that 2018 The Ringer dials more extreme in terms of tannin structure, residual sugar and glycerol while scoring considerable lower on Lactic acid. So 2018 The Ringer leans more towards astringency and sweetness while 2018 Radio Silence dials higher in terms of acidity. Let's next turn our attention to the flavor profile.  subimage6 Here we find a slightly higher astringency score for 2018 The Ringer and more pungency for 2018 Radio Silence. These were just a few glimpses of the insights we can get into wines by applying the wonderful toolbox of analytical chemistry. That is unleashing the power of the natural sciences to understand wine better. Expect more insights to come as analytical methods get refined.