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Mar 20, 2017

Vintage 2017 – Low Sugar but High malic acids

With the challenging weather conditions this season, many wine regions are encountering high malic acid concentrations this vintage (i.e. > 3 g/L, up to 4-5 g/L), and this is also accompanied with low sugar. Even though potential alcohols are not expected to be that high, the unusually high malic acid concentrations may well cause some difficulties with malolactic fermentation.

Lallemand Oenology have a lot of experience with MLF.  What does high malic acid mean for the ML bacteria;

  • High malic acid will translate into high lactic acid concentrations, which can be inhibitory to O. oeni (3 g/L lactic acid).
  • Some wine bacteria are more sensitive to lactic acid than others. In the Lallemand O. oeni range, Lalvin 31™, Lalvin VP41®, O-MEGA™ are the most suited; it is not recommended to use ALPHA™ in high malic acid wines.
  • It is important to have favourable wine composition (pH > 3.2, SO2 <30 ppm) with high malic acid concentrations

In order to ensure an efficient and complete MLF, Lallemand Oenology have some suggestions to assist with your MLFs.

Wine Yeast

  • Select a yeast strain that can undertake malo-ethanolic fermentation, a biochemical pathway whereby some malic acid is degraded during alcoholic fermentation. Malo-ethanolic yeast strains in the Lallemand yeast portfolio are Lalvin 71B™ and Lalvin C™ (these strains can metabolise up to 45% of malic acid during AF).

White wine

  • Wines with a low pH; it is important to have < 30 ppm SO2, and aim for pH >3.1
  • Co-inoculation with Lalvin 31™, Lalvin VP41®, O-MEGA™
  • OptiML Blanc will help bacterial metabolism in low pH and/or low turidity conditions; it improves MLF kinetics

Red wine

ML Prime™

ML Prime™ (Lactobacillus plantarum), only to be used as co-inoculation (with pH >3.4), is well suited for red vinification and will complete MLF very quickly during AF.  Unlike O. oeni, ML Prime™ is lactic acid tolerant.  This strain will efficiently metabolise up to 3 g/L malic acid and under favourable conditions (temp ca 24°C, moderate alcohol and pH >3.6) it can degrade up to 4 g/L malic acid.

Stuck or sluggish MLF (Red and white)

Where the MLF has slowed down or stopped, Lallemand can recommend a few strategies to get the malic acid below 0.2 g/L. For wines with < ~0.8 g/L malic acid;

  • Use a higher dose of ML bacteria to get the MLF started again. Lalvin VP41® (MBR) is the strain of choice for restarting a stuck MLF.
  • For difficult/challenging wine, acclimatization of the bacteria to the wine with 1-Step protocol will help the bacteria adjust to the wine conditions and be metabolically active for malic acid degradation. Additional information can be found in the Procedure – Acclimatization of MBR bacteria for the induction of MLF in difficult conditions.

 

 

 

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