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Malolactic Bacteria
WLP675 Malolactic Cultures
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 wine.
These liquid cultures are
available in vials to inoculate 6 gallons or 1 liter sizes to
inoculate 60 gallons.
Please note: We recommend caution with using WLP675 with wine
kits, which contain potassium sorbate and effect the viability of
malolactic bacteria. Under FAQ questions below, you will find
instructions for using WLP675 with wine kits.
General Instructions
Wait for fermentation to reach a gravity of approximately 5 Brix,
towards the end of fermentation. Warm culture
to room temperature and inoculate must.
If one inoculates at the beginning of fermentation, the yeast and
WLP675 could compete for resources and
may cause a stuck fermentation.
To determine the completion of the MLF (malolactic fermentation),
monitor the depletion of malic acid. The accepted value for a
completed MLF is around 30ppm.
Inoculations larger than 59 gallons
To inoculate larger volumes, we recommend inoculating with a
larger culture. 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.
Propagation Instructions
White Labs recommends allowing 7 days for tenfold growth. The
best media for propagation is apple or grape juice (or must, if
available), supplemented with fructose, malic acid, and nutrients
such as that contained in MRS broth. Approximately
2% of the total volume of media can be composed
of finished wine, in order to
acclimate the bacteria to alcoholic conditions. We recommend an
incubation temperature of 30˚C. More information on propagation
can be found under FAQ questions below.
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.
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).
SO2
The SO2 tolerance
= 10ppm
Best Before
The “best before” date is approximately 6 months after
testing and packaging by White Labs.
FAQ:
Read other wine FAQs
Adding potassium metabisulfite:
Q: If I use your cultures to induce Malolactic fermentation after
the primary, is it okay to still use potassium metabisulfite prior
to the start of alcoholic fermentation to kill the wild yeast?
If so, should I use less than normal (50mg/L)?
A: Yes, you can still add the metabisulfite as you normally
would. The amount that is used at the beginning to inhibit the wild
yeast will eventually dissipate once fermentation begins so it will
not affect the malolactic fermentation that occurs later on.
Sulfite Tolerance
Q: What sulfite level will Malo tolerate?
A: The amount of free SO2
should be at 10mg/L or less in order for the Malolactic to survive.
Using Malolactic in conjunction with wine kits
Q: We are a winery and we use wine kits. The info on your website
mentions that you do not recommend use of this type of fermentation
with the wine kits because the kits use potassium sorbate. My
question is this: the potassium sorbate is added at the stage of
clarification and stabilization. If I do not add the potassium
sorbate until after the MLF is complete (or not at all), is it o.k.
to use this process with the wine kit? How long does MLF take?
A: The Malolactic can be added successfully, if the potassium
sorbate is added after completion. Malolactic fermentation
usually takes 4-6 weeks to finish (30ppm malic acid).
Are additional nutrients needed?
Q: I wanted to know if any nutrients are
needed for using the WLP675 Malo bacteria culture. My retailer
offers no special nutrients for this product, and I would like to
know what is needed, if anything.
A: There are no nutrients needed for WLP675, although adding
yeast extract or a complete yeast nutrient can help aid the MLF.
Minimum temperature
Q: What is the minimum temperature that I need to maintain for
WLP675 Malolactic?
A: 60F is the recommended low, however this strain can tolerate
down to 55F.
When do I add Malolactic?
Q: Do you add WLP675 Malolactic bacteria to wine before it’s
pressed from the skins or after it’s pressed? Also, if the sugar
level (brix) is 0, is it bad for the skins to remain in contact with
the juice while the bacteria settles in?
A: The bacteria should be added before pressing, at around 5 Brix.
If the wine is already down to 0, it should be okay for a few days
with the Malo added without adversely affecting the finished wine.
What occurs if added after pressing?
Q: I am an amateur wine maker. My local wine shop suggested
that I try your Malolactic cultures. I crushed cabernet grapes and
fermented them for 7 days. Your instructions make it sound like I
should have added it to the must and let it ferment longer before
pressing the must. Please let me know if I have done this wrong.
A: It is best to add the Malo before pressing so that the
bacteria will have some sort of nutrients to work with. If the
culture is added after pressing, it may just take a little longer to
begin MLF, but should be enough to take off (although slowly).
In addition, adding yeast extract or a complete yeast
nutrient can help the fermentation be successful, even after
pressing.
Malolactic & Filtering:
Q: Can WLP675 Malolactic tolerate the action of racking the wine
or running it through a filter with a mechanical impeller type pump?
A: It can tolerate the filter, depending on the filter size.
If it is larger than .2 micron, it should still be able to flow
through the filter.
Propagating Malo in larger quantities
Q. You were very helpful last year when I had some questions
about my White Labs bacteria and I wanted to ask a few more
questions as the grapes are soon here. I plan to purchase 5 vials of
the WLP675 and propagate the bacteria to satisfy 100 gallons of
Cab/Merlot/Cab Franc blend. For propagation, should I use 1/4
distilled water, 3/4 apple juice and make a 500ml batch and then
split it? This is what you suggested when I used only 2 vials. Will
I need to add more than a 1/4 tsp of malic acid?
A. If you plan on using the 5 vials to propagate, I would recommend
using a larger juice batch – at least 1 liter. In this case, you
would also need to double your addition of malic acid. If your
propagation media volume is too small, you could risk competition
for nutrients between the bacteria, resulting in lower cell growth.
Mouth feel, aroma and taste
Q: Can you tell me what affects it has on mouth feel, aroma and
taste and whether it produces significant amounts of volatile acids
or biogenic amines?
A: It doesn’t produce significant amounts of either. Because it
converts malic acid to lactic acid, it reduces the harsh, astringent
mouth feel that can sometimes be present in new red wines. In
general, it rounds out the flavor characteristics of the wine, but
it doesn’t produce much in the way of flavor components that would
be noticeable in wine.
Best before dates
Q: The WLP675 Malolactic vial I purchased has
been expired by 5 months. I have a one 6 gallon fermenter of Cab Sav at 8 brix. Would this
malo still be okay to use?
I have a second vial with the same date -- should I use both in the same 6 gal fermenter in case they are "probably " viable but possibly getting weak? Can too much be used?
A: The malolactic vial is quite a bit past its expiration date. We usually give it about a 6 month window upon packaging for maintaining proper viability levels. This vial could be at best, 11 months old. If you cannot purchase a new vial that has not expired, the only way you can know for sure if the bacteria is still viable is to make a small starter with the vials. To do this, use 1-2 liters of apple juice with ~0.5 g of yeast extract and sterilize it by boiling. Place into a sanitized container with a lid, cover and let cool down to room temp. Add your vial to this in as sterile a manner as you can, replace the cap tightly and let grow for 5-7 days in a warm place. After this period, if you shake it up and pressure starts to build in the container, you know you’ve got growth. If not, the culture would not have been viable.
The 5 Brix is a rule of thumb that we recommend, but the malo will work fine in a wider range than that.
When to add the malo?
Q: Is 5 brix the surest sign to know the best time to add the
malo?
A: The 5 Brix is a rule of thumb that we recommend, but the malo will work fine in a wider range than that.
Which quantities to buy?
Q: I plan on doing my malolactic fermentation
in five gallon carboys and racking into larger barrels after the
fermentation. Should I purchase the 1-liter amount or vials and
propogate?
A: 1 liter is good for 100 gallons, otherwise you can use one vial in each 5 gallon carboy. If you want to propagate, you would use the 1:10 step up ratio to attain 650-750mls of malolactic culture (that would be 2-3 vials into 650-750mls for one week).
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