Conducting a successful malolactic fermentation

Conducting a successful malolactic fermentation

Parameter Recommendation Action


Fruit condition

Between 3.20 and 3.50

Visible rot, off odors

Acid addition after cold soak


Crush/Destem Maceration


Potential alcohol

<40 mg/L total for white

<70 mg/L total for red


Minimize SO2 by using sound grapes

Harvest parameters

Alcoholic Fermentation Yeast strain Use yeast strain that is compatible with ML bacteria Check with yeast supplier
Malolactic Fermentation

Inoculation strategy:Timing, Strain






MLF progress

Inoculate with starter culture

Post-alcoholic fermentation

consider strains recommended for certain difficult wine conditions

64-71°F (18-22°C)

< 5 mg/L free

< 13.5%

3.20 to 3.50

Consider ML nutrients if vineyard lots have been problematic in the past or you used high nutrient demand yeast strain

Conduct MLF on yeast lees

Regular monitoring

Microscopic examination for Lactobacillus, Pediococcus

Monitor VA as indicator of spoilage bacteria PCR analysis

Direct, Step 1, or Build up: follow manufacturer recommendation

Strains available with low pH tolerance, high SO2 tolerance and high alcohol tolerance

Inoculate while wine still warm from primary ferment Temp-controlled cellar/tanks

NO SO2 additions until MLF complete

Consider higher alcohol tolerant ML strain

Use acclimatization steps for culture prior to inoculation

Acid adjustment if necessary (not recommended during MLF)

Be alert to microbial spoilage issues if you have a high pH

Follow manufacturer recommendation

Keep wine on light lees during MLF

Paper chromatography, enzymatic analysis, external lab analysis

If presence of spoilage bacteria consider lysozyme and re-inoculation after 2-3 weeks

Post Fermentation & Aging MLF completion Malic acid < 30-50 mg/L Confirm with enzymatic assay or external lab analysis before making SO2 addition

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