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Inquiring Winemaker TIM P A T TERSON et's contemplate a very basic winemaking decision, one that gets made a zillion times ev- ery year—so often that the an- swer must be obvious. For five points: Is it better to inoculate for malolactic fermentation only after the alcoholic fermentation is completed, or is it better to get them all over with and do both at the same time? While you're thinking of your answer, consider that virtually every supplier of yeast and bacteria thinks that co-fermen- tation is (most of the time) the best way to go, and that the vast majority of wine- makers in the United States run with the sequential program instead. Time's up. And the answer is: it de- pends. (If this matter was simple, I wouldn't have an article-length topic.) For enlightenment, I turned to a number of technically savvy folks who also have experience selling yeast and bacteria to perplexed winemakers: Jose Santos of Enartis Vinquiry, Russ Robbins of AEB USA, Sigrid Gersten-Briand of Lallemand, Pete Salamone of Laffort, Lars Petersen of Gusmer, Duncan Hamm of Chr. Hansen and Lisa Van de Water of Vinotec Napa. I also consulted The Wine Lab, which these days dispenses advice, not products. For those of you who always suspect a pecu- niary motive every time a supplier offers an opinion, remember that in this case they will be selling you both kinds of mi- crobes anyway, regardless of the order in which you deploy them. L Matters of viewpoint You can approach this question from the standpoint of the malolactic bacteria Oenococcus oeni (known before 1995 as 52 WINES & VINES OCTOBER 2012 To Co-Ferment Or Not To Co-Ferment Leuconostoc oeni): its needs and desires, its hopes and dreams. Or you can adopt the perspective of the yeast, normally our friend Saccharomyces cerevisiae: its re- quirements and preferences, its survival chances and vulnerabilities. Most of the time, these two roads will end up at the same destination—but not always. Your ferment will stick harder than Gabby Douglas' dismounts in the London Olympics. With your bacterial hat on, you want to provide your designated bugs with an en- vironment that, for several days or a few weeks, makes them go forth and multiply and perform acidic alchemy in a reliable fashion. That means you want a stew with good edibles—most of all malic acid, plus some amino acids and other stuff. Pure ni- trogen in the form of ammonia, so dear to yeast, is useless for the oenies. (In memory of the late malolactic guru Dr. Ralph Kun- kee, we will call them weenies.) You need some heat, somewhere in the 60º-80ºF range. You do not want an extremely low pH (less than 3.2), and you certainly don't want a lot of ethanol, which is a se- rious stressor. Unless you like doing extra work, the best time to get this whole favorable pack- age, including the low alcohol, is dur- ing the alcoholic fermentation. The juice/ wine bath is warm and nutrient-rich, and the bugs get a chance to adapt gradually to the rising ethanol. They suffer none of the shock they get when you throw them into a full-bore wine environment with depleted nutrients and 15% alcohol. You could save a lot of money heating tanks to complete the delayed malo. As a major bonus, you get both ferments done earlier, hastening that magic point when a dash of sulfur can lock in stability. It sounds too good to be true: The bugs are happy, the yeast activity provides the warmth, the fungi have sugar and ni- trogen for food—it's win-win. But if for some reason the yeast aren't up to the task—the wrong strain, bad rehydration, uncontrolled temperature, nutrient defi- ciencies, excessively high alcohol—and the fermentation stalls out and sticks, you are, as Jose Santos delicately put it, "screwed." You have, as Lisa Van de Wa- ter put it, "sweet Cabernet Sauvignon with completed malo." Yum! The oenies do not compete much with the yeast for goodies under normal cir- cumstances, having different preferences, but in a stuck fermentation they aren't shy about piling on. When they run out of ma- lic acid, they'll eat sugar, which produces VA, and they will suck up the other nutri- ents the yeast need if they are ever to get back on track. Other bad lactic actors will have a field day, resulting in elevated vola- tile acidity, toxic acetic acid and one seri- ous mess. Your ferment will stick harder Highlights • The timing of alcoholic and malolactic fermentations is a perennial debate in the wine industry. • Most California winemakers complete alcoholic fermentation before starting the malolactic. • Virtually all of the suppliers of yeast and bacteria think that some form of overlapping co-fermentation is the best course for most wines.