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The following is a guest post by Jan Shrem of Clos Pegase Winery. Ever wondered what that sediment is that settles at the bottom of your bottle or glass of red wine? Read on to find out!

Deposits of sediment in red wine. What are they? Are they safe? Is the wine still okay?  When will the economy recover?

The first thing I will emphasize is that not only is sediment harmless (it is the organic content of the grape), but it is the sign of quality wine, with fining and filtering avoided, since they remove many of the quality components of a wine. And rather than being a short cut, it is actually the labor-intensive requirement of making fine wines.

Sediments in red wine are typically of two types: colloids and tartrates. The smaller, grainier types are colloids of pigment, polysaccharides, and protein. They typically form much more slowly in wines meant for aging, and will start to form slight noticeable deposits after a few years. It doesn’t matter if the wine has been fined or filtered, an older red wine will always form some sediment; careful decanting is recommended if you wish to avoid transferring the sediment to your glass.

The second type of sediment is caused by the formation of potassium bitartrate crystals (cream of tarter) from the potassium and tartaric acid naturally present in grapes and wine. The creating of these crystals and their ability to precipitate, or salt out, is enhanced by cooler temperatures. Normally red wines spend two winters maturing in oak casks, which allow the tartrates to form in the barrel and to be removed from the wine prior to bottling. The difficulty with red wines is that they can often hold more bitartrates in solution (supersaturation) than would be expected because the alcohol tends to prevent the tartrates from salting out. In two years’ time, the wine may not have dropped all of its cream of tarter.

These red wines are then bottled and shipped to market, where, unfortunately, they may be exposed to cold temperatures (less than 50° F) during shipping, warehousing, or storage in a basement or garage in the dead of winter. If you hold a red wine at a colder temperature for an extended period of time, you will almost always create bitartrate crystals. The only option a winemaker has is to cold stabilize the wine before bottling. This is done by chilling the wine for several weeks at near freezing temperatures and then filtering the wine before bottling.  This is perfectly acceptable for inexpensive red wines, or even rosé, but not for age-worthy reds.

At Clos Pegase, I make every effort to avoid fining or filtering our wines to ensure that the full bouquet and textural qualities of the wine make it to your glass. Wine is a dynamic, natural beverage that is meant to change and transform over time. One year it will be quite showy and effusive, the next shy and in retreat, followed the next year by something quite different than before. Sediment is evidence of its native ability to change.

I hope these general notes help to explain how deposits form as well as Clos Pegase’s commitment to make wines in a more traditional way, even if we have to accept a bit of sediment forming in the bottle. Remember, these sediments are completely natural and harmless if consumed. The best way to avoid them is to pour slowly so the sediments catch in the shoulder of the bottle, which can be done either into a decanter or directly into the glass.

Photos courtesy of Clos Pegase Winery. Thanks, too, to Pairing to Perfection for help with this post!