I’m an amateur winemaker who will be harvesting 100 lbs of merlot this Saturday. This will be my first time making wine from fresh grapes instead of a kit, and I was hoping someone could provide some guidance on malolactic bacteria. First, is there a particular type that is recommended by varietal? Also, all the websites I found that sell it have packages to make very large quantities of wine (VP41 - 66 gal). Does anyone know of a website that sells MLB in smaller quantities? On that note, what is the ratio of MLB to gallons of wine that should be added?
I tried searching but didn’t seem to have much luck. Thanks a lot in advance.
Good luck with the winemaking. You’ll have lots of fun.
Wyeast sells a liquid O.oeni culture which you should be able to get from homebrew shops that stock Wyeast. They will have a recommended pitching rate. MLF bacteria can be capricious so if your pH is below 3.2 you might need to deacidify a small amount of your wine to get the bacteria moving and then pitch into the wine you want to inoculate. You can pitch MLF bacteria while primary fermentation is still going but wait until the final stages if you do that. If you are going to make wine each year it is worth investing in a cheap paper chromatography kit so you can see when malo has finished in order to make your SO2 addition (since MLF bacteria can not grow with more than 10 ppm free SO2).
They have some ML bacteria in small quantities that should be fine for your 100 lb. of fruit. Or you could get one of the 2.5 gram packets too - just use a small portion of the packet for whatever amount of wine you’re making. At places where I’ve worked, we haven’t always inoculated with ML bacteria, but when we’ve done that, we’ve used a 2.5 gram packet for 2-3 times the 66 gallons of wine mentioned. If you’re using a carboy, it will take very little to get your MLF going. You might consider getting a little ML nutrient too but it will probably work fine without that.
With the first of about 35 tons due to come in tomorrow to the two wineries I work for (a very small amount by commercial winery standards), it’s a reminder that that’s still a lot to home winemakers where 66 gallons can be seen as a “very large quantity” of wine!
But I don’t think it really makes much difference as far as grape variety. Of more concern would be ML strains that will work well with low pH as Andrew mentioned (though that’s probably unlikely with Merlot) or high alcohol. You’ll probably want to figure out whether these conditions will be issues with your wine - either can make finishing malolactic fermentation more difficult. You’ll also want to try and make sure your wine is not too cold while it’s going through MLF.
Thanks everyone for the replies. I get the impression that the quantity of ML bacteria used is not that relevant, meaning I could use 1.5 grams or 2.5 grams for my 100 lbs and it won’t make any difference?
MLB inoculation is not always required. Keep your tank full, keep temperature around 20 C, %vol below 14, don t overdo it with SO2 (total SO2< 50 ppm) and be a bit patient. Monitor MLF by measuring TA.
I’m also curious about this. You can monitor progress by getting weekly/monthly/whatever TA…as long as the TA continues to drop then you probably have MLF. But you can’t know when it’s complete this way. Also, you can’t distinguish between TA dropping via MLF vs tartrate precipitation.
Eric,
A more basic question (for me):
Isn’t lactic acid titratable?
A switch from malic to lactic decreases TA or does it just decrease perceptible acidity?
Best, Jim
Lactic acid is titratable but it isn’t as strong as malic acid. Malic acid has two hydrogen ions that can become dissociated (i.e. hydrogen ions that can become disconnected from the acid molecule’s base…ph is a measure of the concentration of dissociated hydrogen ions in solution, and TA measures the number of hydrogen ions that are or can be dissociated). A lactic acid molecule only has one hydrogen ion that can become dissociated…so lactic acid contributes less to the TA than malic acid does. When MLF occurs, each malic acid molecule becomes one lactic acid molecule (+ some CO2)…since lactic is weaker, MLF reduces the TA of the wine.
Perception of acidity is interesting. The claim is that TA is a better measure of the perception of acidity than PH is…but I’m not convinced: Add 0.01 gr/liter of citric acid to a wine (as a test, obviously)…a 0.01 gr/liter change in TA is an extremely small change…yet there will be a huge change in the acid perception. Not sure what practical value this has, other than it’s interesting (to me).
If you don’t mind me jumping in -
Yes, lactic is titratable. But MLF does decrease TA and raises pH because about 2/3 of the malic acid converted becomes lactic acid. The other third becomes CO2. The CO2 production is why the proton counts changes as Eric mentions.
Monitorring MLF with pH than TA is not that easy. You need to have a pH meter ($$$) , and also it is a bit difficult to see the progress of MLF, because it is difficult to have measurable differences in values btw the measurements.
TA it is easier to see the drop in acidity (even make a graph). A rule of thump is measuring TA every 2-4 days, and you expect a total drop of around 1 gr/lt expressed as tartaric acid, for malic acid content in the wine of around 2 gr/lt. Most of grape varieties that i have worked with are around 1.8-2.2 but depends the variety, climate season etc etc. When you see the TA being stable, either you measure malic acid (also citric if you want to be 100% sure) or you cross the fingers and add SO2.
I was wondering the same thing - pretty simple and easy to see the progress of ML that way. In any case, pH meters are not that expensive, you should be able to find a decent one in the $50-100 range. And besides, if you’re doing a titration for TA, it will be more accurate if you determine the endpoint using a pH meter.
Paper chromatography is very similar, just uses special paper sheets. Pretty inexpensive and accurate way to monitor MLF and the standard way I’ve seen for many small winemaking operations that don’t have more elaborate lab setups. You don’t get a quantitative measurement, but you can test for malic after it looks like it’s done on the chromatography test. In my experience, the malic is always very low to none measured on subsequent tests after the MLF looks done on the paper chromatography test, though of course we test in any case.
Well, at least in my country pH meter is quite expensive. 300-500 euros plus if you have to change electrode annually you need extra 140 euros. For small wineries i usually suggest TA while i use RQflex (reflactometer) for end MLF point. Unfortunately most small wineries cannot use TLC or P Chrom. because (at least i suggest) they find a bit complicated or too scientific…
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