Red Wine Vinegar

From Season 4: Salad 101

Twenty years ago, white, cider, and red wine vinegars dominated the vinegar section of your local supermarket. Balsamic vinegar now owns 15 percent of the vinegar trade-the same share as red wine vinegar. But red wine vinegar is no slouch. Its unmistakably zesty flavor is the reason why many restaurant chefs are rediscovering it.

The source of that notable edge you taste when sampling any red wine vinegar is acetic acid, the chief flavor component in all vinegar and the byproduct of the bacterium Acetobacter aceti, which feeds on the alcohol in wine. The process of converting red wine to vinegar once took months, if not years, but now, with the help of an acetator, a machine that speeds up the metabolism of the Acetobacter aceti, red wine vinegar can be made in less than 24 hours.

Does this faster, cheaper method -- the one used to make most supermarket brands -- produce inferior red wine vinegar? To find out, we included in our tasting vinegars made using the fast process (acetator) and the slow process (often called the Orleans method, after the city in France where it was developed).

What's in That Vinegar, Anyway?

We first tasted 10 nationally available supermarket brands in two ways: by dipping sugar cubes in each brand and sucking out the vinegar and by making a simple vinaigrette with each and tasting it on iceberg lettuce. We then pitted the winners of the supermarket tasting against four high-end red wine vinegars.

Tasters preferred sweet and fruity vinegars that were "full-bodied". Vinegars that were overly acidic or found lacking in grape flavor were panned. Although acetic acid is the predominant source of flavor in red wine vinegar, other factors contribute to overall taste. One is the quality of the red wine used to make it. No single grape variety is thought to make the best red wine vinegar. Still, we were curious to find out if our tasters were unwittingly fond of vinegars made from the same grape. We sent the vinegars to a food lab for an anthocyanin pigment profile, a test that can detect the 10 common pigments found in red grapes. Although the lab was unable to distinguish specific grape varieties (Cabernet, Merlot, Pinot Noir, and the like), it did give us some interesting information: Some of the vinegars weren't made with wine grapes (known as Vitus vinifera) but with less expensive Concord-type grapes, the kind used to make Welch's grape juice.

Did the vinegars made with "juice grapes" fare poorly, as experts might expect? Far from it. The taste-test results were both shocking and unambiguous: Concord-type grapes not only do just fine when it comes to making vinegar, they may be a key element in the success of the top-rated brands in our tasting.

Nor did the aging process contribute heavily to the rankings. Our winning brand isn't aged for even one minute, although the red wine used to make the vinegar is aged.

At this point we had discovered that the difference between a good product and a mediocre one was neither wine grapes nor the aging of the vinegar. Could it have something to do with the way the acetic acid is developed?

The Orleans method was the first commercial method used to make red wine vinegar and remains the preferred technique for makers of specialty vinegars. It involves adding a small amount of vinegar containing the "mother" bacteria to a wooden cask filled with red wine and waiting for them to do their work. The wine converts to acetic acid within a few months. The vinegar is then siphoned to another barrel for aging. Manufacturers that mass-produce vinegar generally prefer not to use the Orleans method because it's slow and expensive.

Unfortunately, while our top brand is made by the Orleans method, its close runner-up is made in an acetator, in which the red wine is converted to vinegar in less than 24 hours. What, then, can explain the ratings? Oddly enough for a food that defines sourness, the answer seems to lie in its sweetness. It turns out that Americans like their vinegar sweet. It is significant that our two top winners start with wines containing sweet Concord grapes.

In the end, the disparity between the best-tasting supermarket vinegars and the middle of the pack was not overwhelming. More significant was the performance of the supermarket champions in the gourmet round; the top two bested gourmet competitors that cost up to eight times as much. Which vinegar should you buy? The answer comes faster than it takes an acetator to convert red wine into vinegar: Skip the specialty shop and head to the supermarket.