Protect Your Wine From Frostbite
When the weather outside is frightful…don’t ship wine
While many of us enjoy chilled wine in the summer and mulled wine in the winter, proper storage temperature is key and adverse weather conditions can damage wine. Summer months, in particular, can be problematic. However, I was recently reminded that the cold can sometimes pose a significant problem, too.
While cold temperatures are not much of an issue overall, extreme cold can certainly take its toll. During our most recent harsh cold-spell, for example, I received six bottles of white wine that were adversely affected by the cold during shipping. Three of the bottles showed signs of relatively significant cold-induced precipitation of tartrate crystals in the wine. The other three bottles had corks that were pushed so far up the neck of the bottle that they were more out than in.
In general, cold slows down the aging and maturation process of wine in-bottle. When the temperature fluctuation is gradual, bottled wine is less immediately bothered than when the shift is rapid. So long as freezing isn’t a concern, cold temperatures present very little problem. This is why putting wine in a chilly basement, even when significantly less than the 55° F “ideal” cellar temperature, is always preferable to a hot attic or a kitchen cupboard near the stove.
Once we start talking about extreme cold like freezing or below freezing temperatures, however, concern is warranted. Not so much for the wine itself, but for its glass bottle.
If a bottle of wine gets really cold for an extended period, the wine inside can seem “cold-zapped,” for lack of a better phrase, exhibiting somewhat muted aromas and flavors. This is not the end of the world, and most wines will recover as they warm back up to a normal temperature.
Once freezing temperatures threaten, however, the wine in the bottle will expand as it freezes. Expanded wine will increase pressure on the cork and potentially compromise the integrity of the bottle itself. The cork may be pushed up the neck, as in my unfortunate bottles, and eventually right out of the bottle altogether. Once the airtight seal between cork and bottle is broken, oxidation (excessive exposure to oxygen in this context) can become a real problem, eventually spoiling the wine. Should the bottle start to leak, the problem can become messy, too.
The issue is fairly straightforward. Alcoholic beverages have a freezing point somewhere between the freezing point of water (32°F) and the freezing point of pure ethanol (-173°F). Most alcoholic beverages contain more water than alcohol, however, so the danger zone for freezing is much closer to residential freezer temperatures. Those of us who have forgotten wine placed in a freezer for rapid chilling or left a wine in the trunk of a car during a winter storm know all too well that wine can become slushy and eventually seem like hard ice once temperatures reach around 20° - 15° F.
If the bottle cracks, the deleterious effects of the cold become obvious upon discovery. A cold-induced compromise of the cork seal isn’t always so immediately apparent, however. When the cold strikes, keep an eye out for a sticky cork, stickiness between the bottle and foil capsule, or even for wine stains under the capsule. Even when these telltale signs are evident, the only definite way to know how the broken seal may have affected the wine is to open the bottle and taste its contents.
Extreme cold can also, again as in the case of my poor bottles, cause a wine to prematurely precipitate tartrates—winemaker speak for harmless crystalline deposits, principally made up of potassium acid tartrate (the potassium salt of tartaric acid), that separate from wines during both fermentation and during ageing. These tartrate deposits can look like little shards of glass in white wines (in reds they tend to pick of the red pigment and tend to blend in with other sediment). Though perfectly harmless, they remain unappealing to most, and downright scary to some. Under normal conditions, this precipitation doesn’t have much effect on the taste of the wine—but it can be noticeable when conditions are less, well, normal.
As winemaker Craig Winchell, formerly owner and winemaker of the now-legendary Gan Eden kosher winery in Sonoma, CA, put it: “Tartrate precipitation will, of course, affect taste relative to what the wine was before the precipitation. It removes 1- hydrogen ion and 1 potassium ion for each tartrate ion which is removed. Since both the hydrogen ion and the tartrate are responsible for the sour flavor buffered by the potassium ion originally (but not after precipitation), the post-precipitation wine should taste significantly less acidic than the pre-precipitation wine, assuming the amount of precipitation was significant.”
This is a large part of why the overwhelming majority of commercial wineries the world over will make sure their wines are “cold-stable” before they are released. That is, commercial wineries use cold temperatures to eliminate this matter in advance in a controlled way so that it won’t be an issue for most consumers under most conditions. Shipping wine when freezing temperatures prevail, however, is a good example of the sorts of conditions wineries worry about—which is why most won’t ship their wines when inclement weather is expected.
As I contemplate all this, I do so while sipping glass of:
De La Rosa, Chai 18, Organic Welschriesling, 2015 ($20; mevushal): This is an expressive, refreshing, aromatic, and a little fruity, medium-dry Austrian welschriesling — unrelated to the riesling grape — with enjoyable aromas and flavors of ripe green apple, citrus, some subtle tropical fruit notes and all supported by somewhat bracing acidity. Versatile and food-friendly. Served lightly chilled.