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Bottle Aging & Sediments…

Aged wines often have deposits at the bottom of the bottle. This happens in white wines and in red wines. For reasons – that we deem psychological – there is much more concern about crystals in white wines than in red wines. These sometimes look like glass, and frighten the person who is about to open that bottle of wine.  Actually these are potassium tartrate and/or potassium bitartrate crystals and they are harmless. These are in the wine whether or not one sees them.  They are dissolved at room, or close to room, temperatures.  Given this perception, most wineries “cold stabilize” white wines. This means that they hold the wine at about zero (0)  degrees Centigrade until the wine is stable, i.e. will not precipitate crystals at that temperature.  Consequently one can leave the wine in a refrigerator and the wine will remain clear.

Red wines also precipitate tartrate crystals, and other chemicals made from tartrates, alcohol, color molecules, and other of the many different chemicals in wine.  Many reactions occur during maturation – or aging. In this article we are discussing bottle aging. Some processes, the precipitation of tartrate crystals, are basically the same as that described for white wines above. Since red wines are not usually served at temperatures that white wines are served at, we see these crystals after the wines are bottled, and allowed to bottle age for one or more years.

A specific reaction that occurs is esterification of tartaric acid – an acid in all wines – by the alcohol in the wine.  The tartaric acid is esterified to ethyl bitartrate, and proceeds slowly as the wine ages in the bottle. Formation on the bitartrate has no direct effect on flavor of the wine, but does at a certain level decrease tartness in a wine.  Interestingly wines in the pH range that De Angelis Wines are made take about 3-3.5 years of bottle aging before an equilibrium of ethyl acid tartrate is reached.  What does all this mean, and why is it good to know about it?

A longer bottle aging time allows reaction of tartaric acid and alcohol, as well as other flavor enhancing reactions to occur in the bottles wines, i.e. new and additional mellowing and a completing of flavors. The overall reaction is slow to reach equilibrium under typical wine storage conditions, but easily accounts for the formation of several hundred milligrams of ethyl acid tartrate per liter during wine aging.  Thus the occurrence of tartrate crystals either at the bottom of a bottle of wine, or on the cork if the wine is stored upside down in the case in order to maintain the cork in a wet state. Wines laid on their side will precipitate tartrates along the side of the bottle.

The sediment which develops in red wine should be removed. A bottle of a younger De Angelis Wines wine that you purchased a couple of months ago, even if it’s a red wine, may not have any sediment. An older wine, recently purchased, may have a bit of sediment. Removing the sediment is easily done by either decanting the wine, or allowing the wine to stand upright for an hour or two before opening, then pouring the wine carefully. If you’re serving a red wine that’s been aging for several years, hold it up to the light to see if a sediment has formed. If so, set the wine bottle upright so all the sediment collects in small area at the bottom of the bottle. Decant as suggested, and enjoy a great wine!.

As noted above, the  presence of various tartrate and other natural products in the wine lends a  wine character and complexity, but you don’t want to leave it in the wine when you serve it. This sediment can have a bitter flavor, or if the sediment is very mild, it can interfere with any of the subtle nuances that have developed during the aging process. Remember tartrate crystals are not a flaw!  They are the natural sequellae of a number of natural processes that occur as a wine ages. Better wines are often ages for years, and the additional flavors that develop are well worth dealing with a few tartrate crystals.







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