Troubleshooting Your Wine
The faults and flaws and their analysis and resolution presented below are from my latest book, Modern Home Winemaking, where you can find additional information should you wish to explore these further.
RESTART PROTOCOL — MALOLACTIC FERMENTATION
STEP 1:
Make sure the wine is at 18–22 °C (64–72 °F). Add 0.1–0.25 g/L of yeast hulls, or as per your product’s instructions, while stirring thoroughly but gently, again, to minimize oxygen uptake. Stir thoroughly every 6–12 hours for 48 hours, and then carefully rack the wine off its lees and into another vessel while minimizing oxygen pick-up to the extent possible.
STEP 2:
Dissolve your choice of MLF activator, such as ML Red Boost or MaloBoost, in a small volume of water or wine, for example, 50 mL for a 23-L (6-gal) batch, then add to the batch of wine and stir thoroughly but gently to avoid oxygen pickup. Keep the wine at 18–22 °C (64–72 °F). Wait 24 hours before proceeding to Step 3.
STEP 3:
Choose a strong LAB strain specifically known to be good at restarting a stuck MLF, such as Lalvin MBR VP41, Lactoenos B16 Standard, Er1A & Ey2d Blend or Viniflora CH35, and prepare or add directly to the wine, as per product instructions, at double the normal rate for the product used. Stir thoroughly but gently. Keep the wine at 18–22 °C (64–72 °F) until MLF completes. Monitor progress using paper chromatography, and sulfite immediately when malic acid has been completely converted.