Malolactic fermentation: Difference between revisions

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'''Malolactic fermentation''' (also known as '''malolactic conversion''' or '''MLF''') is a process in winemaking where tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often performed as a secondary fermentation shortly after the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as [[Chardonnay]], where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.
{{Short description|A process in winemaking that converts malic acid to lactic acid}}


== Process ==
'''Malolactic fermentation''' (MLF) is a process in winemaking where tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. This process is carried out by lactic acid bacteria, primarily ''Oenococcus oeni'', although other species such as ''Lactobacillus'' and ''Pediococcus'' can also be involved.
The bacteria that perform this conversion are known as lactic acid bacteria (LAB). Species include [[Oenococcus oeni]], [[Lactobacillus brevis]] and [[Pediococcus damnosus]]. These bacteria are not yeast, and are thus not responsible for primary fermentation which turns sugar into alcohol.


== Role in winemaking ==
==Process==
Malolactic fermentation tends to create a rounder, fuller mouthfeel. Malic acid is typically associated with the taste of green apples, while lactic acid is richer and more buttery tasting. It also reduces the acidity of the wine, which can make it seem smoother and less tart.
Malolactic fermentation typically occurs after the primary alcoholic fermentation, although it can sometimes occur simultaneously. The process involves the decarboxylation of L-malic acid to L-lactic acid and carbon dioxide. This conversion reduces the acidity of the wine and can contribute to a smoother, rounder mouthfeel.


== Risks ==
[[File:Malolactic fermentation diagram.png|thumb|right|Diagram of malolactic fermentation process]]
While malolactic fermentation can improve the flavor profile of the wine, it can also create problems. The process can generate flavors that are generally considered to be off-flavors, such as butyric acid (which smells like rancid butter) and ethyl lactate (which has a solvent-like smell).


== See also ==
The reaction can be summarized as follows:
 
: C_H_O_ (malic acid) _ C_H_O_ (lactic acid) + CO_ (carbon dioxide)
 
==Role in Winemaking==
Malolactic fermentation is a crucial step in the production of many wines, particularly red wines and some white wines such as [[Chardonnay]]. It can influence the flavor profile of the wine, adding complexity and buttery notes due to the production of diacetyl, a byproduct of the process.
 
===Benefits===
* '''Acidity Reduction''': MLF reduces the acidity of the wine, making it more palatable and balanced.
* '''Flavor Complexity''': The process can introduce new flavors and aromas, such as buttery or creamy notes.
* '''Microbial Stability''': By converting malic acid to lactic acid, MLF can help stabilize the wine and prevent spoilage by other microorganisms.
 
===Challenges===
* '''Control''': Winemakers must carefully control the process to avoid excessive diacetyl production, which can lead to undesirable buttery flavors.
* '''Timing''': The timing of MLF is critical; if it occurs too early or too late, it can affect the quality of the wine.
 
==Techniques==
Winemakers can encourage malolactic fermentation by inoculating the wine with specific strains of lactic acid bacteria. Alternatively, they may allow it to occur naturally, relying on indigenous bacteria present in the winery environment.
 
===Inoculation===
Inoculation involves adding a cultured strain of ''Oenococcus oeni'' to the wine. This method provides more control over the process and can ensure a consistent outcome.
 
===Natural Fermentation===
Allowing MLF to occur naturally can result in more complex flavors, but it carries the risk of unpredictable results and potential spoilage.
 
==Impact on Wine Styles==
Malolactic fermentation is more common in red wines, where it is almost universally practiced. In white wines, the decision to undergo MLF depends on the desired style. For example, [[Chardonnay]] often undergoes MLF to achieve a rich, buttery flavor, while other white wines may avoid it to preserve crisp acidity.
 
==Related pages==
* [[Winemaking]]
* [[Fermentation (wine)]]
* [[Fermentation (wine)]]
* [[Yeast in winemaking]]
* [[Lactic acid bacteria]]
* [[Acids in wine]]
* [[Chardonnay]]


[[Category:Winemaking]]
[[Category:Winemaking]]
[[Category:Fermentation processes]]
{{stub}}
<gallery>
File:Malolactic_spotting.JPG|Malolactic fermentation
File:Hermann_Müller_(1850-1927).jpg|Hermann Müller (1850-1927)
File:Malolactic_fermentation.svg|Malolactic fermentation
File:Chardonnay-UVa.jpg|Chardonnay grapes
File:O._oeni.jpg|Oenococcus oeni
File:Malolactic_inoculation_and_nutrient.JPG|Malolactic fermentation
File:20101210_014809_LactobacillusBulgaricus.jpg|Lactobacillus bulgaricus
File:Acrolein.svg|Acrolein
File:Sediment_at_bottom_of_wine_barrel.jpg|Sediment at bottom of wine barrel
File:Harvested_grapes_being_loaded_into_crusher_destemmer.jpg|Harvested grapes being loaded into crusher destemmer
File:Transferring_wine_to_a_barrel.png|Transferring wine to a barrel
File:Membrane_filter_without_housing.jpg|Membrane filter without housing
</gallery>

Revision as of 17:44, 18 February 2025

A process in winemaking that converts malic acid to lactic acid


Malolactic fermentation (MLF) is a process in winemaking where tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. This process is carried out by lactic acid bacteria, primarily Oenococcus oeni, although other species such as Lactobacillus and Pediococcus can also be involved.

Process

Malolactic fermentation typically occurs after the primary alcoholic fermentation, although it can sometimes occur simultaneously. The process involves the decarboxylation of L-malic acid to L-lactic acid and carbon dioxide. This conversion reduces the acidity of the wine and can contribute to a smoother, rounder mouthfeel.

File:Malolactic fermentation diagram.png
Diagram of malolactic fermentation process

The reaction can be summarized as follows:

C_H_O_ (malic acid) _ C_H_O_ (lactic acid) + CO_ (carbon dioxide)

Role in Winemaking

Malolactic fermentation is a crucial step in the production of many wines, particularly red wines and some white wines such as Chardonnay. It can influence the flavor profile of the wine, adding complexity and buttery notes due to the production of diacetyl, a byproduct of the process.

Benefits

  • Acidity Reduction: MLF reduces the acidity of the wine, making it more palatable and balanced.
  • Flavor Complexity: The process can introduce new flavors and aromas, such as buttery or creamy notes.
  • Microbial Stability: By converting malic acid to lactic acid, MLF can help stabilize the wine and prevent spoilage by other microorganisms.

Challenges

  • Control: Winemakers must carefully control the process to avoid excessive diacetyl production, which can lead to undesirable buttery flavors.
  • Timing: The timing of MLF is critical; if it occurs too early or too late, it can affect the quality of the wine.

Techniques

Winemakers can encourage malolactic fermentation by inoculating the wine with specific strains of lactic acid bacteria. Alternatively, they may allow it to occur naturally, relying on indigenous bacteria present in the winery environment.

Inoculation

Inoculation involves adding a cultured strain of Oenococcus oeni to the wine. This method provides more control over the process and can ensure a consistent outcome.

Natural Fermentation

Allowing MLF to occur naturally can result in more complex flavors, but it carries the risk of unpredictable results and potential spoilage.

Impact on Wine Styles

Malolactic fermentation is more common in red wines, where it is almost universally practiced. In white wines, the decision to undergo MLF depends on the desired style. For example, Chardonnay often undergoes MLF to achieve a rich, buttery flavor, while other white wines may avoid it to preserve crisp acidity.

Related pages