Tartrate crystals

Sometimes people freak about things found in wine when they should celebrate. Tartaric crystals, for example.

Tartaric crystals—wine diamonds—are found on the cork or floating in the wine. They are the color of the wine. They can be an indicator of quality.

Three main acids are in wine: tartaric, malic, and lactic. All are completely natural.

Tartaric is the most important. It helps maintain chemical stability and color and influences the final taste of wine. Less than half of tartaric acid is free-standing, the remainder binds with potassium to form a crystal, potassium bitartrate, the same thing as cream of tartar used in cooking.

The crystals are harmless. They are exactly the same as the tartaric acid you cannot see, in the same way ice floating in water is crystalized water, not a fault. They are more common in white wines because red wines have less tartaric acid and crystals tend to fall out during the longer aging of red wines.

Tartaric acid is responsive to temperatures below 40 degrees. Many mass-market pours go through a stage of “cold stabilization” in order precipitate crystals so they can be filtered. This helps ensure clarity, but it negatively affects wine flavors and hurts the wine’s ability to age.

Malic acid gives wines apple flavors (malum is Latin for “apple”). Lactic acid is milder than tartaric or malic, and it derives from malic acid through process of malolactic fermentation. It is associated with milky flavors, but exploring malic and lactic is for another column.

Today’s take-away: When you discover tartaric crystals on a cork or floating in your glass, celebrate. The wine diamonds signal more nuances and flavor complexity, not flaws.

Tasting notes:

Corona de Aragon Special Selection Garnacha-Cariñena 2013: Astonishing value in Spanish red. $6-7

Les Dauphins Côtes du Rhône Reserve 2015: Simple GSM, lovely label, excellent value. $9

Bodegas Escorihuela Gascón Malbec Mendoza 2015: All you expect from Argentine malbec. $15

Whitehall Lane Sauvignon Blanc Napa Valley 2015: Fruit over tartness, layers of depth. $18

Franciscan Estate Sauvignon Blanc Napa Valley 2015: Dependable, tart, food-friendly. $18

Last round: I hate it when I see older-looking people in a wine bar, then realize I graduated high school a year ahead of them.

Email Gus at wine@cwadv.com. Facebook: Gus Clemens on Wine. Twitter: @gusclemens.