Designation for the conversion of malic acid in the milder-tasting lactic acid (lat. malum = apple, lac = milk) used in the production of fruit juice, Wine and sparkling wine ( champagne. sparkling wine ) plays an alternative role. The process is also referred to as malolactic fermentation (BSA), bacterial malic acid digestion, microbial acid degradation or malolactic fermentation, as well carbon dioxide is released. It is actually not a correct one fermentation but was held earlier for it. Around 1890, the then suspected in Geisenheim active Dr. Hermann Müller-Thurgau (1850-1927) rightly bacteria as a cause. Dr. Wenzel Seifert (1862-1942) could then 1903 on Klosterneuburger Weinbauinstitut identify the acid-degrading bacterium and named it "Micrococcus malolacticus". The BSA is almost always today red wine but basically in front of you Barrique, applied. The benefits are reduction of malic acid, more fullness due to the lactic acid, less need for sulfur dioxide and better microbiological stability.
Especially White wines can be a typical buttery-creamy malolactic grade exhibit. If the BSA does not work properly, heavy wine mistakes like bitter. vinegar sting. Geranienton. Lindton. Mannitstich or Lactic acid sting (Yoghurt / sour cabbage) possible. It can also color loss in low-color red wines and taste impairments occur. The loss of fruitiness This is one of the reasons why white wine (with the exception of Switzerland, where it is common practice) usually does not have a BSA. Although white wines also contain malic acid, in contrast to red wine, this is desirable here because it makes the wine sparkling and refreshing. In some grape varieties such as Chardonnay, the BSA can sometimes quite serve the refinement, as far as the so-called buttery Sound is desired. This is also common with some producers of the chablis, The process is but with fruity wines such. B. the Riesling or bouquet places hardly used.
It is a natural process in the winemaking, which is spontaneously set in motion at about 16 ° C by already existing or possibly by added bacteria (Oenococcus oeni). If no malolactic fermentation is desired, the wine must be fermented as soon as possible lees deducted, clarified and sulfurized. It can also spontaneously and independently (even during the alcoholic fermentation) arise, what by cooling and reductive expansion can be prevented. A regulation or interruption are also by addition of the enzyme lysozyme possible. If explicitly requested, the BSA is deliberately initiated or authorized after alcoholic fermentation. The start can be made by stirring up the gel, by blending with a wine already in the BSA process or (which is usually the case) by adding so-called starter cultures These are special Lactic acid bacteria, respectively.
At this time, a must sulphurize be sure to refrain because the starter cultures are very sensitive to it. The required or ideal wine temperature for this process is about 22 ° Celsius. In the wine ideally an acidity or PH value of at least 3.2 pH (below which there is no increase in lactic acid bacteria) and one Residual sugar content be given below 20 g / l. It is first the malic acid, then the citric acid and lastly the residual sugar converted. As a rule of thumb, 2 grams of malic acid will produce about 1 to 1.2 grams of lactic acid. The total acidity decreases in the wine by about 1 g / l.
The malolactic fermentation can take between 10 to 40 days; that can be a relatively long process. Sometimes only part of the wine undergoes this process so that the acidity is not too low; then the wine is mixed. The process is very complex and must be closely monitored by measuring the amount of malic acid. An uncontrolled or excessive acid degradation is as drop in acidity (Wine error) to classify. Once the BSA has ended, it is only allowed to sulfurize after one to two weeks clarify respectively. During this period oxygen access is to be prevented (full containers). In case of improper operation can allergenic Substances like histamine and tyramine be formed. See also below deacidification and leavening,
Complete listings of the numerous vinification measures and cellar techniques, as well as the various wine-regulated wine, sparkling wine and distillate types are under the keyword winemaking contain. Comprehensive information on wine law is available under the keyword wine law,