New World Winemaker Blog

Some time ago, an inquisitive mind inquired of me as to whether being lactose intolerant could affect the sufferer’s tolerance of wine that has undergone malolactic fermentation. Fair question. “Lactose” and “lactic” are obviously related, and thinking about an intolerance to the “lactic” in wine is a sensible leap with everyone and their brother speculating over what causes wine headaches and the like (derivatory of the overarching food intolerance fad, I expect.)

The good and the bad news is that lactose intolerance has no bearing whatsoever on the ability to digest malolactically-fermented wine. Good news, as the lactose-intolerant among us can drink wine without reservation. Bad news, as the lactose-intolerant among us are equally as enlightened as everyone else as far as identifying a cause of the wily wine headache, i.e. still in the dark. Short answer: lactose intolerance is unrelated to the ability to tolerate wine that has undergone malolactic fermentation. Longer answer: Most people who react poorly to lactose suffer from an intolerance, not an allergy.

Allergies are inappropriate immune responses to specific epitopes, which can be thought of as molecular shapes. An intolerance, on the other hand, isn’t necessarily an immune response. Lactose intolerance is caused by a deficiency in the enzyme responsible for breaking down lactose in the small intestine. Since we can only absorb lactose after it has been broken down into its component parts – glucose and galactose – a lactase deficiency means that undigested lactose builds up in the intestines to cause bloating, diarrhea, gas, and other discomforts. Unlike lactose, lactic acid can be absorbed without first being acted upon by the lactase enzyme.

Incidentally, even if lactic acid absorption was somehow related to lactose absorption, quantity would be a pertinent consideration. Milk contains 2-8% lactose, i.e. relatively a whole lot, while wine contains much less than 1% lactic acid. In conclusion, then, the lactic acid in wine should be of no concern to most people who need to avoid lactose. A glass of wine makes a far friendlier companion to a good dinner than a glass of milk, don’t you think?

Erika Szymanski is an independent contributor to this blog. She is in no way affiliated with the sponsoring company. This blog was originally posted on her blog: The Wine-o-scope.

Délestage – (‘dehl-luh-STAJ’) aka “rack and return” (though the French sounds much more refined and romantic, as usual.) refers to the practice of repeatedly draining fermenting red wine off of its skins through a screen that traps some portion of the seeds, then returning the drained-off juice to continue fermenting on the skins, but minus the seeds entrapped in the draining process. Fewer seeds = lower seed-to-juice ratio = less extraction of seed tannins into juice = less tannic wine.

You know that it can’t really be that simple. There are two reasons why just describing the mechanics of the operation is inadequate. First, the “rack and return” process does more than just remove seeds. Like other methods of cap management*, the process also douses the floating grape skins. Unlike some other methods of cap management, délestage generally incorporates a lot of air into the must when the juice is pumped back over the skins.

Besides stimulating their growth, oxygen discourages fermentation yeasts from producing unsavory cooked cabbage and onion-like sulfides. Oxygen also has far-reaching and often poorly-understood effects on myriad elements of wine chemistry. Tannin polymerization, for example, is influenced by oxygen in complex ways that seem, in general, to lead to softer and rounder wines In fact, the role of oxygen in winemaking is so very complex that I’m going to refrain from saying any more about it here for fear of perjuring myself. In any case, the influence of délestage on a wine can’t just be attributed to removing seeds; oxygen must play a part, too.

The second reason why délestage is more complex than its mechanical description comes from our understanding – or, rather, our lack of understanding – of tannins themselves. We once separated tannins into the two broad categories of seed tannins and skin tannins. Seed tannins were bad: harsh, bitter, and green. Skin tannins were better: softer and malleable. In this context, délestage makes a lot of sense. Decreased exposure to bitter seeds during fermentation should reduce harsh, bitter flavors.

For better or for worse, tannin chemists, led by Dr. Jim Harbertson at WSU, have shattered this simplistic understanding. Tannins are polymers of flavon-3-ols. According to Harbertson’s work, longer tannins are usually perceived as more astringent, yet seed tannins are about a third of the length of skin tannins, averaging ten instead of thirty units. On the other hand, seed tannins take longer to extract than skin tannins; even though seed tannins outweigh skin tannins in magnitude, they release more slowly. To add yet another layer of complexity, the make-up of each tannin polymer influences its sensory characteristics in addition to its sheer length. And even then tannin experts haven’t yet deciphered what happens to tannins over time to make well-aged wine seem softer and less harsh than its youthful counterpart. For more on this topic without delving into the scientific literature, try this palatable Wines and Vines article.

The upshot of how to use délestage in the face of all of this complex chemistry? Taste, taste, taste. I’m no winemaker, but isn’t this self-evident? Superb winemakers have been making superb wine for centuries before anyone ever named or knew of a flavon-3-ol. Intuitively, it makes sense that removing seeds will reduce seed-y flavors. If that makes your wine taste better, go for it. As for oxygen, even if it remains the great unknown variable, scientific uncertainty doesn’t invalidate your taste buds.

*Cap management – grape skins are pushed, parachute-like, to the top of the must by CO₂ bubbles created by the fermentation process, creating a “cap” of skins that can literally float above the surface of the must. Free from the protective effects of alcohol and acid and exposed to air, this cap will rapidly submit to spoilage microorganisms if not frequently reincorporated into the must. Hence, in making red wines, the “cap” must be “managed.”

Erika Szymanski is an independent contributor to this blog. She is in no way affiliated with the sponsoring company. This blog was originally posted on her blog: The Wine-o-scope.

To say that something tastes “goaty,” in common parlance, is to say that it tastes like goat milk or cheese. I suppose that English-speakers are, in general, more familiar with goat-derived dairy products than they are with goat meat. Too, goat milk is so distinctively flavored that its presence screams through anything to which it is added. Regardless, wine isn’t usually goaty. Usually.

Goaty flavors are apparently related to three fatty acids, the “goaty acids,” C6 (caproic acid), C8, (caprylic acid), and C10 (capric acid.) [NB: incidentally, the Latin name for “goat” is Capra.] These acids collectively comprise 15% of the fats in goat milk (thank you, Wikipedia.) All three have been found in wine. A wine that smells and/or tastes like goat, therefore, probably contains unusually high amounts of these acids.

Why do I mention all of this? By now, you may have guessed – correctly – that I have recently encountered a goaty wine.

The goaty acids are found in grapes and can be produced by both wine-related yeast and bacteria. What I’ve been trying for the past week to learn is what affects the amount of these acids produced by each source. Medium-chained fatty acids (MCFAs), including the goaty C6, C8, and C10, are antimicrobial, inhibit the growth and reduce the rate of growth of both yeast and malolactic bacteria, and are related to stuck fermentations.

MCFAs can slide into the phospholipid bilayer that ordinarily seals the interior of the cell off from its environment. When this happens, the permeability of the membrane increases; in other words, the cell springs a leak (or, rather, many tiny leaks.) This is, needless to say, dangerous.

The research published on wine microorganisms and MCFAs is vast. Synthesizing all of the primary data is more like the subject of a solid literature review for the American Journal of Enology and Viticulture, not a blog post. Still, I’ve read enough to fairly conclude that the matrix of MCFA production by and influence on microbes and grape vines remains something of a mystery.

None of this helps me understand why a particular Finger Lakes wine tastes like goat. Or, more particularly, why several wines from a particular Finger Lakes winery taste like goat. Sheldrake Point was new ground for me on my most recent visit to my old wine-tasting grounds in upstate New York. Though I now live within easy driving distance of the wine-rich pastures of eastern Washington, my parents are still close enough to the Finger Lakes to be practical. A Christmas visit afforded an excellent chance to get up to the lakes, revisit several old favorites, and explore a new winery or two. We detoured from the eastern border of Seneca lake to the western side of Cayuga lake and Sheldrake Point on the advice of a Seneca winery tasting room manager. I’m glad we did. None of the wines was remarkable – consistently okay, but not great – but either the terroir of Cayuga lake is dramatically different than Seneca or else Sheldrake Point has a style all its own. “Goat cheese” was a common thread not only through the whites but also into the pinot noir, as was a lightness that stood out even among the typically light-bodied wines of upstate New York.

A few interesting notes about Sheldrake. First, it seems that they do enjoy an unusual mesoclimate. Like the rest of the Finger Lakes, they enjoy the temperature- and humidity-buffering effects of a deep neighboring body of water. Unlike most of the regions’ wineries, however, their vineyards come down nearly to waters’ edge. Their grapes also bed down on the remains of an old cattle ranch. Could that have something to do with those unusual flavors? Finally, I should point out that my impressions were far from normal: Sheldrake Point’s 2008 Late Harvest Riesling took “Best Sweet Riesling in the World” and “Best American Riesling” at Australia’s 2010 Canberra International Riesling Festival and the winery has been named “Winery of the Year” for two years running by Wine and Spirits Magazine and the New York Wine and Food Classic. Heck, maybe I’m weird.

Erika Szymanski is an independent contributor to this blog. She is in no way affiliated with the sponsoring company. This blog was originally posted on her blog: The Wine-o-scope.

WHAT: a yeast that divides by fission (division in half, rather than budding like most yeast, hence “Schizo”), ferments sugars (hence “saccharomyces” or “sugar-loving”), and was first identified in African millet beer (hence “pombe” meaning “beer” in Swahili.)

Relevance to wine: S. pombe has traditionally been grouped among the spoilage organisms by the wine industry. Unlike its friendly, helpful cousin Saccharomyces cerivisiae (the major player in wine fermentation and bread making), S. pombe tends to throw off a lot of icky-tasting or -smelling byproducts as it turns sugar into alcohol. Sulfur is not a desirable aroma in wine!

S. pombe has one truly nifty feature; however, that is earning it a useful place in winemaking. It can ferment malic acid into alcohol. Malic acid is one of the three major acids in grape juice that carries over into wine (along with tartaric acid and citric acid.) Its fresh, fruity acidity is a boon in fresh, fruity wines, but too much and you’ll find yourself puckering.

The usual savior of malic acid overload is malolactic fermentation – conversion of malic acid into lactic acid by lactic acid bacteria after alcoholic fermentation yeasts have worked their magic. Great for rich, buttery wines — lots of unctuous flavors come along with the malic-to-lactic conversion — but not so great if you were going for a fresh and fruity style in the first place.

Could S. pombe help? What about the sulfur aromas and other issues?

A fair bit of research has investigated ways of using S. pombe in wine: to permit the inclusion of rotten grapes in Sherry and the potential of using genetic engineering to create a Schizoid-Schizosaccharomyces that keeps the good and does away with the bad, for example.

Lallemand, a major yeast company, has recently released ProMalic® “for naturally lowering juice acidity,” based on S. pombe. The yeast is submerged in the wine in something like a big yeast tea-bag, allowed to steep until your pH is up (and your malic acid down) to where you want it, and then pulled out before the yeast gets carried away with making other less-desirable stuff.

Some super-enthusiastic yeast folk from the Forsberg lab at the University of Southern California say that they have tried fermenting beer with their pombe with results that suggest skunk cabbage more than the local brewpub. With a respectful nod to classic eastern African beverages, however, they note that their attempts involved neither millet nor traditional methods. Anyone tasted any African millet beer?

Some home-brewers out there are apparently giving it a try: http://www.homebrewtalk.com/f12/pombe-brew-138520/ 

For the truly curious yeast fiends out there, see the Forsberg lab Pombe pages at http://www-bcf.usc.edu/~forsburg/main.html#what for a truly excellent discussion of pombe in all its glory.

Erika Szymanski is a PhD student in microbial enology at Washington State University and an independent contributor to this blog. She is in no way affiliated with the sponsoring company. This blog was originally posted on her blog: The Wine-o-scope.