The SOMM Journal

June / July 2017

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Page 120 of 124

120 { THE SOMM JOURNAL } JUNE/JULY 2017 WINE STYLES INFLUENCED BY MLF CAN BE EITHER { scents & accountability } SUMMER WEATHER IS CONDUCIVE to classic Vinho Verde, a youthful wine style from northern Portugal that is defined in part by the refreshing and intentional prickle from trapped CO 2 that historically originated from malolactic fermentation (MLF) taking place in the bottle. Modern-day Vinho Verde producers have resorted to completing MLF prior to bot - tling to avoid the sediment that is its inevitable by-product and adding CO 2 to mimic its prickle. Malolactic fermentation is a conversion, also referred to as res- piration, that takes place when the family of lactic acid bacteria (LAB) that can include Oenococcus oeni and various species of Lactobacillus and Pediococcus ingest malic acid and respire lactic acid, liberating carbon dioxide in the process. As it's a naturally- occurring process, MLF fermentation has been around as long as fermentation itself. However, the manipulation of MLF either by suppressing, limiting or initiating it is a relatively new practice ascribed to modern winemaking. Because MLF reduces acidity and raises pH in finished wine, typically reducing titratable acidity (TA) by 1 to 3 g/l and increasing pH by 0.3 units, it's not suitable for all wine styles. In varieties like Riesling and Gewürztraminer it's considered a fault, and although almost all still red wines undergo MLF, if it occurs in bottle where CO 2 can be trapped, the only way to describe the result is spoilage. What surprises fans of Chardonnay styles from both ends of the spectrum—from steely and austere to dripping butter—is that they both rely on MLF for their charm and popularity. How is it that Chablis, a wine style that often undergoes 100 percent MLF, remains free from the buttery, creamy characteristics so often associated with New World Chardonnay? Although yogurt is a common descriptor for Chablis that points to MLF, in its absence it's a guessing game as to whether MLF was employed. Wines from cooler growing regions such as Chablis naturally have higher levels of malic acid, making MLF an important technique for de-acidification and enhancing body and mouthfeel. MLF has also been seen to reduce excessive vegetative and grassy notes in wines made from underripe grapes. But in Chablis, malic acidity is off the hook; it's the conversion of citric acid by LAB, notably Pediococcus species, that creates diacetyl. The higher the initial concentration of citric acid, the more diacetyl will be produced during MLF. Winemakers manipulate MLF by choosing when to inoculate, working anaerobically to keep concentrations of diacetyl low and keeping the wine on its lees, employing the Burgundian winemaking practice of bâtonage, to allow both yeast and LAB to convert any diacetyl to yogurt-like acetoin and odorless 2, 3 butendiol. Chardonnay oozing diacetyl, more reminiscent of movie pop - corn than the Chardonnay grape, is a wine style that met its height of popularity in the 1980s and encountered a backlash in the 1990s but has preserved. While diacetyl rarely faults Chardonnay, the industry has since seen a shift in style towards less apparent MLF characteristics. Fans of the overt style have wine brands— most notably JAM Cellars' Butter—that clearly communicates this style and caters to their tastes. In red wine production, MLF is de rigueur for increasing the polymerization of tannins and anthocyanins and for reducing astrin - gency. When MLF takes place in an oak barrel, LAB enzymes react with soluble substances creating enhanced aromas of spice, smoke, roasted and chocolate notes. However, MLF can reduce primary fruit aromas and impact color in addition to being the source of a host of flaws and faults (previously discussed here) among them bitterness or amertume, Geranium taint, ropiness or graisse, mousi - ness, mannitol (artificial sweetness) and refermentation. It' s no surprise that winemakers prefer to inoculate for MLF with O. oeni, steering clear of Lactobacillus and Pediococcus to avoid off flavors and corrections. When they do, consumers should expe- rience fewer red wine headaches, which are likely caused by a reaction to the biogenic amines, ammonia derivatives, produced by Pediococcus. Fashion or Faux Pas? The genus Lactobacillus currently contains over 180 species. by Deborah Parker Wong

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