Malolactic culture assistance
In a recent issue of Craft Beer Quarterly, we told
you that White Labs now offers liquid malolactic culture for the home
winemaker. In this issue we will provide you with instructions and tips
for malolactic fermentations.
Malolactic fermentation is the conversion of malic
acid to lactic acid by bacteria from the lactic acid bacteria family.
Lactic acid is less acidic than malic acid, which in turn decreases
acidity and helps to soften and/or round out some of the flavors in
Please note: We do not recommend the use of WLP675
with wines from kits, which contain potassium sorbate and affect the
viability of malolactic bacteria.
1) General instructions:
Wait for fermentation to reach a gravity of
approximately 5 Brix, basically towards the end of fermentation. Warm to
room temperature and inoculate 5 to 7 gallons (20 to 25L) of must.
If one inoculates at the beginning of fermentation,
the yeast and WLP675 could compete for resources, thereby causing a
To determine the completion of the MLF (malolactic
fermentation), one can use paper chromatography and monitor the
depletion of malic acid. The accepted value for a completed MLF is
2) Inoculation of Must Volumes larger than 7 gallons
Each vial of WLP675 can inoculate up to 7 gallons or
25L. To inoculate larger volumes, we recommend inoculating with more
vials. If time is not an issue, one can propagate the bacteria to larger
volumes, but keep in mind that malolactic bacteria is a slow-growing,
fastidious organism. Depending on the size of the propagation, it could
take weeks to grow.
3) Propagation instructions
White Labs recommends allowing 7 days for tenfold
growth. The best media for propagation is tomato juice, supplemented
with fructose, malic acid, and nutrients such as that contained in MRS
broth. Diluted apple or grape juice supplemented with malic acid is a
good substitute for tomato juice. Approximately 2% of the total volume
of finished wine can be added in order to acclimate the bacteria to
alcoholic conditions. We recommend an incubation temperature of 86°F
4) Optimal pH
The optimal pH is approximately 4.0, but WLP675 will
handle a pH of 3.3 in red wines and 3.1 in white.
5) Additional Information
WLP675 has a high tolerance to low pH (3.0), low temperature
environments (down to 55°F or 12°C), and high alcohol percentages (up
to 15% alcohol by volume).
For information on any of the above information, please call 1-888-5-Yeast-5,
or write the sales staff.