MALOLACTIC FERMENTATION
Is It Right For You and Your Wine? Maybe!

It is the ambition of most home winemakers' to make the best wine
they can; one that can be enjoyed with great pride and be worthy
of recognition. As I see it, wanting to be good at something is
only natural and very consistent with human nature. After all who
wants to spend their time making a "just average" wine worthy of
no recognition?

This yearning to make a remarkable wine has its benefits and
downfalls alike. It causes the winemaker to be careful in all
that they do, to follow directions closely and such. And, it
gives them a passion to explore and try different, more advanced
techniques; something that helps to make home wine making a more
interesting pastime.

This is all well and good in of itself but only if these advanced
techniques are applied with discretion and complete
understanding, otherwise one may find themselves out on a limb,
so to speak. This is where the subject of malolactic fermentation
fits into this discussion.

Quite often we find home winemakers wanting to apply the
technique of malolactic fermentation to their wines simply
because they read about it in passing somewhere and it sounded
interesting. In effect they were given just enough information to
perk their interest but not enough information to apply the task
in sound fashion. In essence they where given just enough
information to hang themselves.

While I'll be the first to say that malolactic fermentation plays
an incredibly beneficial role in the world of wine making, at the
same time one must understand that it is certainly not something
that can be applied whimsically to any wine. And, it definitely
does not guarantee that you will have a better wine. The effects
that it has may or may not be to your liking, nor may it be
appropriate for the particular wine you are making. In some cases
it may actually ruin the wine.


- What Is Malolactic Fermentation?

In very basic terms malolactic fermentation (also known as MLF)
is a process where certain types of bacteria degrade the malic
acid that is available in a wine into lactic acid and CO2 gas. It
is a very natural process and one that can occur spontaneously if
the conditions are right--usually after the yeast fermentation has completed.

It can last anywhere from a couple of weeks to three or four
months depending on:

- The amount of malic acid available in the wine
- The strength of the culture, and
- The conditions under which the fermentation is being performed.

On average, you can expect an MLF to last 3 to 6 weeks if a
domesticated culture is added to the wine.

A spontaneous version of this fermentation is limited for the
most part to juices that have not been sterilized as opposed to
juices that have been subjected to sulfiting or pasteurization.
The difference being that a malolactic bacteria is not present to
flourish in a sterilized juice.

There are thousands of different strains of malolactic bacteria.
Some of them have better effects on a wine than others. For this
reason wineries will usually elect to inoculate a selected wine
with a known malolactic culture instead of hoping Mother Nature
will do the job to satisfaction on her own.


- How Does A Malolactic Fermentation Affect A Wine?

Professional wineries will often seek to have this process occur
in a given wine for one or more of the following reasons:

To Add Stability To A Wine:
By inducing a malolactic fermentation now it insures that one
will not occur later at a less convenient time--like after the
wine has been bottled. Bottled wines that go through an
uncontrolled MLF will typically become cloudy, sometimes forming
a sediment, and be slightly carbonated with an odor that is
remarkably similar to sauerkraut. By taking a wine and putting it
through the paces of an MLF, under controlled conditions with a
selected strain of malolactic culture, this risk is eliminated.

The risk of having an unwanted malolactic fermentation is very
small when making wine with packaged juices and concentrates. The
stability issue is more of a concern with wines made from the
grape itself. If an MLF is not desired in a particular wine for
other reasons such a flavor, then stability can also be achieved
by treating the wine with a sulfite of some type.


To Lower The Acidity Of A Wine:
A grape juice may be too high in acid due to geographical
climate, or maybe it was just a bad, short season in that area.
By inducing a malolactic fermentation the winemaker can reduce
the overall acidity of the wine.

There are two reasons for this:

- The lactic acid is not as acidic to taste as malic acid. So, as
the malic acid is converted to lactic acid the acidity of the
wine lowers.

- Not all of the malic acid is being turned into lactic acid.
Some is turned into CO2 gas. Approximately only 2/3 of the malic
acid is turned in to lactic acid. The rest simply turns in to CO2
gas and goes away.


To Alter The Character And Flavor Of A Wine:
Wines that go under an MLF will also change in body and flavor,
partially due to the softer, smoother character of lactic acid
verses malic acid, and partially due to the various by-products
that can come off of this type of fermentation. These changes may
or may not be welcomed depending on the wine in question.

Wines that go through a malolactic fermentation tend to be much
less fruity in flavor and aroma. This lack of fruitiness is
mostly replaced with a deeper, richer, more complex character.
The texture of the wine is often creamy and a slight hint of
buttery to vanilla flavor can often be noticed. This is due to
the diacetyl that is produced during an MLF.


- What Types Of Wines Should Be Subjected To MLF?

Based on the information given above you might be starting to see
why not all wines should be considered candidates for a
malolactic fermentation.

For example, wines made from fruits other than grapes such as
blackberries or cherries probably should not be considered. After
all it is the fruitiness of these types of wines that make them
distinct, and as stated earlier malolactic fermentations will
reduce this fruitiness. To treat fruit wines with an MLF would
simply wipe out the best asset these types of wines have. So in
general keep MLF's away from wines made from fruits other than
grapes.

The same goes for lighter, fruitier wines made from grapes such
as Zinfandel or Liebfraumilch. These wines should not be
subjected to MLF. To do so would only bring them out of balance
and give them a character that would be considered unusual--at
best--by the average wine drinker.

So, what kind of wines should be considered for malolactic
fermentation? The answer is fairly straight forward. Consider
full-bodied wines that already have some rich, earthy notes to
them. The idea here is to only consider wines that already have
some of the same characters that an MLF produces so that they can
be built upon or enhanced by the process.

This narrows down the field for the most part to big, heavy red
wines. To help give you an idea, wines such a Pinot Noir, Merlot
and Cabernet can do quite well with the added influence of a
malolactic fermentation.

White wines are not usually consider appropriate for an MLF,
however one major exception to this rule is the Pinot Chardonnay
grape. Wines made from this grape are often treated with MLF by
commercial wineries both in the U.S. and abroad. Chardonnay wines
posses the flavor intensity and body required to handle the
effects of malolactic fermentation.

I must point out here that this does not mean that all
full-bodied, red wines or Chardonnays should be subjected to MLF,
nor does this mean that you can not make an exceptional wine
without the aid of MLF. To the contrary, most home winemakers
never deal with MLF and still win at wine tasting competitions,
at regional judgings, and state and county fairs on a regular
basis.


- When And How To Induce A Malolactic Fermentation?

The When:
Malolactic fermentations are best done right after the yeast
fermentation has completed. Think of it as something you tag on
to the end of the fermentation, when the gravity reading is .998
or less. There are several reasons why MLF is best induced at
this time and not before or after.

Malolactic cultures have the ability to consume sugars just like
yeast. But, instead of turning these sugars into alcohol--like
yeast does--they slowly convert these sugars into volatile acids
such as acetic acid; the same acid that puts the sharp pucker in
vinegar. So, one could conclude just from this information that
during the yeast fermentation, when there is still sugars in the
must, is not a good time to induce MLF.

Another thing to consider is that malolactic fermentations are
even more sensitive to sulfites than yeast. So, if the must is
treated before fermentation with sulfites such as Campden Tablets
or Sodium Bisulfite--as you should--lingering amounts could
easily interfere with the ability of an MLF to start. Only later,
after the fermentation activity has caused all of the sulfites to
dissipate off the must, is it safe to start an MLF.

The fact that MLF is very sensitive to sulfites is also the
reason why it should be induced and completed before sulfites are
added to stabilize the wine. Typically one would add sulfites
again at the end of fermentation to reduce the chance of
spoilage. Not so if you want to induce MLF. Hold off adding any
sulfites until the MLF has completed.

The same rule applies to adding Potassium Sorbate. While an MLF
can occur in the presence of Potassium Sorbate doing so will
often produce a fowl odor, usually a strong geranium to ripe fish
smell.

What does this all mean for someone wanting to have an MLF when
making wine from ingredient kits? First off they must realize
that it will require them to deviate from the directions that are
provided, and that not all of the directions will be completed on
the time table that is provided with such kits.

The ingredient kit's directions will typically tell you that once
the fermentation has completed to siphon the wine into a clean
container and add a packet of sulfite of some kind. Stop! After
the fermentation ends and before a stabilizer of any kind is
added; this is when you want to induce a malolactic fermentation.
It is okay to siphon the wine but do not add any sulfites or
other types of stabilizers.

The malolactic fermentation will occur over the next several
weeks. After it has completed you will continue on with the rest
of the directions just as nothing happened.


The How:
While one could try to depend on an MLF to come along naturally
it is a bit like rolling the dice. There are an endless number of
bacteria strains that are capable of converting malic into
lactic. The problem is that these strains come with all sorts of
side-effects. Some are pleasant, but most bring defects to the
wine. And, there is always the chance that an MLF will not occur
on its own at all.

This makes inoculation with a known MLF culture the preferred
method used by most wineries today. The MLF cultures are
typically available for the home winemaker in packets sufficient
for 5 or 10 gallons of wine. Each packet can easily be cultured
into larger amounts for batches up to 50 gallons in volume.

For more information on the Malolactic Culture we offer, go to
the following link listed on our web site:
Malolactic Culture

Its use is very simple. If you are wanting to inoculate 5 or 10
gallons of wine simply pour the contents of the package directly
onto the wine at the appropriate time. If you are wanting to
inoculate more than 10 gallons a starter will be required so that
the culture will have a chance to increase in size.

The packets of MLF culture we offer can only be cultured
sufficiently for batches up to 50 gallons in volume. For batches
larger than this a second packet of MLF culture will be required.

The most difficult thing about making an MLF starter is that it
needs to be started a couple of weeks before it is needed if it
is to be worth the effort. This requires a little forethought on
your part.

For every 10 gallons of wine to be inoculated take 1 quart of
apple juice and 1/4 teaspoon of Ghostex (yeast extractive) and
add it along with the packet of MLF culture to a gallon jug or
something similar and cap it with an air-lock. When it comes time
to use the culture simply stir it into the wine. Again, the
starter needs to prepared a couple of weeks before it is needed.

You can find the Ghostex needed to make the starter listed at the
following link on our web site:
Ghostex

There are some variables that effect the rate of a malolactic
fermentation. First and foremost is temperature. Just like a
yeast fermentation the wine should be kept between 70 and 75
degrees F. Temperatures cooler than this will slow the MLF.
Temperatures warmer than this will promote unwanted bacterial
growths.

Wines that are extremely high in acid (very low pH) may have a
hard time fermenting. Ironic as this may seem, there are some
wines that have acidity levels that are simply to far out of
range to be corrected with a malolactic fermentation. While
domesticated MLF cultures are more tolerant of lower pH levels,
you may have problems getting a complete MLF in a wine with a
starting pH of 3.1 or lower.

Wines that are high in alcohol (13% and above) may have problems
supporting an MLF. Just like having too much acid, the alcohol
acts as an inhibitor to MLF activity. While it is possible for an
MLF to occur slowly in wines with higher alcohol, one should
consider making a starter to help better the odds.


- What To Do After The Malolactic Fermentation?

Once the malolactic fermentation has completed there are a few
things that should be done before bottling, or in the case of
ingredient kits, before moving on to the next step.

The wine will need to be siphoned into a clean container. It
should be done in a splashing manner so as to aerate the wine.
Aeration is needed to help release unwanted odors that often come
with an MLF.

Once aeration is complete you then will need to add sulfites such
as Campden Tablets or Potassium Bisulfite to the wine. This is
usually the next packet called for when making wine from an
ingredient kit.

Once aeration and sulfiting both have been completed you will
then want to check the acidity level of the wine to determine if
any replenishment of acid is needed. There will be times when an
MLF will lower the acidity too much, causing the wine to be
insipid and susceptible to infection while in storage.

You can test the wine with the aid of an Acid Test Kit. It will
tell you if your wine is in an acceptable range and how much acid
to add if it is too low. You can find the Acid Test Kit we offer
at the following link on our web site:
Acid Test Kit

If you do need to add acid to the wine, tartaric acid should be
used. If malic acid is used this could trigger another malolactic
fermentation. If citric acid is used any remaining MLF culture
could slowly convert the citric acid in to acetic acid (vinegar).
This also means that Acid Blend should not be used to bring up
acid levels. Acid Blend contains both malic and citric.

For more information about the Tartaric Acid we offer, go to the
following link on our web site:
Tartaric Acid


- Related Article

"Getting A Handle On Acidity"
 

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E. C. Kraus

Home Wine & Beer Making Supplies

Address: 733 S. Northern Blvd. - P. O. Box 7850 - Independence, MO  64053

Phone:(816) 254-7448  Fax:(816) 254-7051  Toll Free: (800) 353-1906

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