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Australia/New Zealand Vintage 2017 – recommendations to manage high acidity, low sugars wines

High malic acid concentrations are being encountered for the 2017 vintage in Australia and  New Zealand. (i.e. > 3 g/L, up to 4-5 g/L), and this is also accompanied with low sugar and pH/TA. In order to ensure an efficient and complete malolactic fermentation there are several aspects to consider.

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.