How do you measure malolactic fermentation

[Xlev]

Hi

I have a question.I will be ordering some grapes for semptember for the first time.The wine will have to go through MLF. I see that there a chromatography kits,but I can only find them in the US and I live in Europe.I cant seem to find any here.There might be an issue shipping the kit to Europe due to the chemicals. Are there any other ways that are reliable to measure the completion of MLF? I also read that MLF can take months to complete,so do you hold off with SO2 potentially for several months until MLF is complete?

Thanks for your help

 

[cmason1957]

Just because you have grapes, your wine does not have to go through MLF, you can add chemicals like lysozome to inhibit the MLF bacteria that might want to try to work and keep you SO2 levels up a bit higher than normal. It is generally considered a good thing for red wines to go through MLF, although I have had some wines where it was inhibited and they were very good.

An alternative you may wish to look into for the chromatography kits is to purchase Accuvin Malolactic Fermentation Test Strips. These are color change test strips and work quite well, I have used them a number of times. I haven't ever tried to stop the conversion at 40ppm malic acid, just is the conversion completed.

 

[heatherd]

If you can't find tests near you, you could go by taste. I have done this in the past. When the fruit flavor turns to smooth, and you like the way it tastes you can stop the MLF.

Yes, hold off on k-meta until MLF is done.

 

[winemaker81]

I have not intentionally done MLF, but follow the threads out of interest.

Let's say I ferment a red, inoculate with MLB, and then bulk age 12 months (which is my normal barrel practice). It's a dry red, I'm not backsweetening, and not using sorbate.

The MLF either works or it doesn't. Why do I care if the result is positive (MLF completed) or negative (MLF did not complete), and most importantly, what will I do differently if it's negative?

@Xlev, sorry to hijack your thread, although answers to my question may help you make decisions.

 

[BarrelMonkey]

The MLF either works or it doesn't. Why do I care if the result is positive (MLF completed) or negative (MLF did not complete), and most importantly, what will I do differently if it's negative?

One reason might be that you don't want MLF kicking off in your bottles... Malic acid is converted to 2/3 lactic acid, 1/3 CO2 so there is theoretically a risk that you might develop a 'spritz' in your wine and/or push corks. You need at least 2-4g/L malic acid for this to happen, which is within the range of malic acid concentrations in grapes. So if there is some doubt as to whether the reaction went off, it might be prudent to add lysozyme as @cmason1957 suggested. If the reaction was mostly successful it shouldn't be an issue - I think I once calculated that if you see a residual malic spot on your chromatogram at around the limit of detection, it corresponds to around 50mg/L malic acid.

@Xlev, I don't have any great suggestions but you could maybe try to source the kit components individually? The main challenge is likely to be the chromatography solvent, which is a ~50% solution of 1-butanol with some formic acid and bromocreosol green dye.

 

[winemaker81]

One reason might be that you don't want MLF kicking off in your bottles

Yeast dies after 9 months. MLB is finicky to start, and is shut down by K-meta. If I bulk age 12 months and add K-meta prior to bottling, is MLF gonna kick off in the bottle?

 

[BarrelMonkey]

Yeast dies after 9 months. MLB is finicky to start, and is shut down by K-meta. If I bulk age 12 months and add K-meta prior to bottling, is MLF gonna kick off in the bottle?

Probably not. It seems that total SO2 rather than free is used to determine whether ML bacteria are going to be inhibited so if you have a regular K-meta program it's likely going to be sufficient to inhibit growth.

ETA: Useful reference on preventing refermentation in the bottle

 

[winemaker81]

@BarrelMonkey, thanks for the reference sheet. Also, your point about total sulfite vs free SO2 is VERY important.

My point here is to get people to think about MLF and draw reasonable conclusions based upon facts. It's not an area of experience for me, so I'm going by the practical experiences of others plus what I read. My conclusion is that for dry red wines and MLF, folks worry too much about things that are very unlikely to happen.

I'm considering inoculating with MLB this fall, and the test strips Craig mentioned are of interest. I need to look more into that.

 

[Xlev]

Winemaker81 I thought that it was necessary to do MLF but now I see that its not a must. I do like dry red wine that is not too acidic though,so I will probably go for that. So it seems like the strips might be a good idea,but also that long enough aging in the carboy might be enough to kill off the yeast and prevent refermentation. But does the malolactic bateria also die after a few months in secondary,because I guess that the issue of the continuation of malolactic fermentation in the bottle is due to the bacteria waking up again.

 

[winemaker81]

Winemaker81 I thought that it was necessary to do MLF but now I see that its not a must. I do like dry red wine that is not too acidic though, so I will probably go for that. So it seems like the strips might be a good idea, but also that long enough aging in the carboy might be enough to kill off the yeast and prevent refermentation. But does the malolactic bateria also die after a few months in secondary, because I guess that the issue of the continuation of malolactic fermentation in the bottle is due to the bacteria waking up again.

I didn't find anything regarding the lifespan of MLB in wine. There's plenty of information regarding storage of cultures, but not while in use. Numerous sources state MLF should complete in 1 to 3 months, but there's nothing about when the bacteria actually dies off.

This FAQ has tips for ensuring a good secondary fermentation. SO2, pH, ABV, and other factors affect success. I suspect that many folks have problems as they don't realize their wine has one or more factors that prevent successful MLF.

https://scottlabsltd.com/en-us/faqs/wine-malolactic-bacteria-faqs
Keep in mind that a wine being acidic to taste does not mean it's a candidate for MLF. MLB eats malic acid, so if the tartaric is high, it will not touch it. It also does not touch artificial malic acid, so adding powdered malic to a wine will not work.

Regarding MLF in the bottle, there's conflicting stories. While I don't doubt @BarrelMonkey's calculation, others state that MLF produces so little CO2 that it can be hard to detect.

IF I try it this fall, I'm going to look into test strips. I'll inoculate when moving the wines into barrels, checking strips before inoculation, and at each monthly barrel topup. I'll probably add K-meta at the 3rd or 4th month mark, depending on what reading I get on the malic acid. In any case, I bulk age 12 months so there is that.

Before doing any of this, I will do more research, to resolve the conflicting things I've read.

 

[BarrelMonkey]

Regarding MLF in the bottle, there's conflicting stories. While I don't doubt @BarrelMonkey's calculation, others state that MLF produces so little CO2 that it can be hard to detect.

Maybe it would help to describe that calculation in a bit more detail...

First, malic acid content in grapes runs from 1-2g/L in hot climates to 4-6g/L in cooler climates (reference - this is also a really nice, if a little technical, review of acids in wine by the guy came up with the Accuvin test strips).

From the document I linked in my post above, malic acid is stoichiometrically converted to 2/3 lactic acid, 1/3 CO2. You need around 800mg/L CO2 to produce a noticeable ‘spritz’ in your wine, and over 1400mg/L to push corks. This corresponds to 2.4g/L and 4.2g/L malic acid respectively. So already it looks like we'd need to convert a significant fraction of total malic acid in the bottle in order to create a problem.

My malic acid standard supplied with the kit is 0.3% (I assume w/v) which is 3g/l. So if I test my wine after ML treatment and spot the same volume of wine vs standard on my chromatography paper, and I get a resulting spot with about the same intensity as the standard, then I’m in a range where I may risk some fizziness in my wine (but not enough to push corks) if my ML bugs remain active in the bottle. (Then again, this would also suggest that the ML reaction had failed or at least not worked to a significant degree...)

The limit of detection for the chromatography technique is listed on my instructions as 70mg/L. So if I see a trace amount of a malic acid spot, that suggests 70mg/L malic acid in my wine, much lower than the level reported to lead to ‘spritz’ in the finished wine if it were to restart ML conversion and go to completion in the bottle. Moreover, there is likely to be a trace smear on the chromatogram just due to the background of the technique, so actual levels might be lower still.

So it's theoretically possible that you might have some ML conversion after bottling, but I don't think it's a big issue if you (a) monitor malic acid and (b) take steps if necessary (K-meta, lysozyme) to inhibit activity if there is a perception of risk based on chromatography or test strips.

 

[rsportsman]

One reason might be that you don't want MLF kicking off in your bottles... Malic acid is converted to 2/3 lactic acid, 1/3 CO2 so there is theoretically a risk that you might develop a 'spritz' in your wine and/or push corks. You need at least 2-4g/L malic acid for this to happen, which is within the range of malic acid concentrations in grapes. So if there is some doubt as to whether the reaction went off, it might be prudent to add lysozyme as @cmason1957 suggested. If the reaction was mostly successful it shouldn't be an issue - I think I once calculated that if you see a residual malic spot on your chromatogram at around the limit of detection, it corresponds to around 50mg/L malic acid.

@Xlev, I don't have any great suggestions but you could maybe try to source the kit components individually? The main challenge is likely to be the chromatography solvent, which is a ~50% solution of 1-butanol with some formic acid and bromocreosol green dye.

Corks can pop and spritz develop at WAY BELOW 1 g/L malic acid. Paper chromatography is unlikely to reliably detect below 0.2 g/L, in my experience.

 

[rsportsman]

Hi

I have a question.I will be ordering some grapes for semptember for the first time.The wine will have to go through MLF. I see that there a chromatography kits,but I can only find them in the US and I live in Europe.I cant seem to find any here.There might be an issue shipping the kit to Europe due to the chemicals. Are there any other ways that are reliable to measure the completion of MLF? I also read that MLF can take months to complete,so do you hold off with SO2 potentially for several months until MLF is complete?

Thanks for your help

Vinmetrica offers the SC-50 MLF kit. SC-50 MLF tester
We also carry the Sentia system, a little pricey but worth a look for the serious home winemaker.

 

[wineview]

@BarrelMonkey, thanks for the reference sheet. Also, your point about total sulfite vs free SO2 is VERY important.

My point here is to get people to think about MLF and draw reasonable conclusions based upon facts. It's not an area of experience for me, so I'm going by the practical experiences of others plus what I read. My conclusion is that for dry red wines and MLF, folks worry too much about things that are very unlikely to happen.

I'm considering inoculating with MLB this fall, and the test strips Craig mentioned are of interest. I need to look more into that.

Is MLB a typo? You mentioned it a few times so it might be intentional. Not familiar with MLB.

 

[winemaker81]

Is MLB a typo? You mentioned it a few times so it might be intentional. Not familiar with MLB.

MLF = malolactic fermentation (you already knew this)

MLB = malolactic bacteria

First time I saw the acronym, my first thought was, "what does major league baseball have to do with winemaking?"

 

[wineview]

MLF = malolactic fermentation (you already knew this)

MLB = malolactic bacteria

First time I saw the acronym, my first thought was, "what does major league baseball have to do with winemaking?"

My thought exactly.....

 

[Cap Puncher]

One of my wine making buddies had a bunch of corks pop on a very nice Syrah after assuming malolactic was done. He had 2 separate fermentors that he inoculated ML during primary. One went through ML, the other didn’t. He sulfited appropriately. He bulk aged a year, bottled, and bottles started popping from the 1 fermentor in which ML didn’t take(about 6 months later). I’d try to test it unless you are 100% confident it went through ML.

A note on lysozyme, it can strip some tannin out and create a large sediment after. Stripping the tannin can change the balance of the wine. So keep that in mind. I went to using Bactiless and like it better than Lysozyme for sure. It is effective against acetobacter too!

 

[Rice_Guy]

Winemaker81 I thought that it was necessary to do MLF but now I see that its not a must. I do like dry red wine that is not too acidic though,so I will probably go for that., , , , But does the malolactic bateria also die after a few months in secondary,because I guess that the issue of the continuation of malolactic fermentation in the bottle is due to the bacteria waking up again.

MLF is a useful tool if one buys grapes from a cool climate as Germany or northern US. MLF will stop in winter/ at temperatures below 10C. MLF can be completely prevented by metabisulfite addition after the yeast fermentation is finished. In a traditional process like French apple cider it is normal for it to stop when temperatures drop and restart in spring and then be finished by summer. If your fermentation area is heated it would be done in two months. Testing is for people who do not bulk age a year,

MLF is not appropriate if you are buying hot climate grapes as Italy or the southern California valley. In this case the flavor balances better/ tastes less thin if you add acid back.
A lower pH wine will have better shelf life, both chemical and microbial. The grams of acid determines how acidic a beverage tastes. Tannins from red grape skins compliment acid taste so one can feel full bodied with lower grams per liter. pH is related to grams of acid per liter but not a predictable relationship. , , , , Back to the original post, if you are buying hot climate grapes adding acid may be needed to have a full body flavor.

 

[winemaker81]

@Xlev, where are you getting your grapes from? @Rice_Guy raised a very good point.

When I lived in NY, I purchased juice & grapes from the Finger Lakes, and generally all were high in acid (colder climate), and I had to cold stabilize on my porch to reduce acid. In recent years I purchase CA grapes (hot climate) and have had to add tartaric to most grapes. If you are getting hotter climate grapes, MLF is probably not a good idea.

I'm considering buying malic acid test strips to check my existing wines for malic acid, and I'll check the pH. It's entirely possible that my grapes are not a good candidate for MLF, so I'll skip it completely.

One of my wine making buddies had a bunch of corks pop on a very nice Syrah after assuming malolactic was done. He had 2 separate fermentors that he inoculated ML during primary. One went through ML, the other didn’t. He sulfited appropriately. He bulk aged a year, bottled, and bottles started popping from the 1 fermentor in which ML didn’t take(about 6 months later). I’d try to test it unless you are 100% confident it went through ML.

I'm making the mistake of thinking about MLB in terms of yeast, but they are too different to do that. On this forum there is a good understanding of the yeast lifecycle, but it appears that (overall) we're light on understanding MLB. Individuals may understand, but as a group it's not clear.

@rsportsman, I realize you're an equipment vendor -- can you point out any technical resources where we can learn more about MLB?

Thanks!

 

[CDrew]

MLF is not appropriate if you are buying hot climate grapes as Italy or the southern California valley. In this case the flavor balances better/ tastes less thin if you add acid back.
A lower pH wine will have better shelf life, both chemical and microbial. The grams of acid determines how acidic a beverage tastes. Tannins from red grape skins compliment acid taste so one can feel full bodied with lower grams per liter. pH is related to grams of acid per liter but not a predictable relationship. , , , , Back to the original post, if you are buying hot climate grapes adding acid may be needed to have a full body flavor.

Say what? It is common to adjust the pH of must or wine with tartaric acid, no doubt, but your statement here is misleading. Even with "hot climate (red) grapes" (which are basically all red grapes/wine in California), still need to go through MLF to assure stability. And honestly, even if not deliberately inoculated, the majority of wines are going to go through MLF eventually anyway, since MLB is present on grape skins. So it's best to control this aspect of wine making. The green apple taste of malic acid is another issue too. It just isn't desirable in red wine.

I'll make a blanket statement that is correct 99% of the time:

All red wine needs to go through MLF.
In white wine making, MLF is a stylistic choice.

Anyway, the pH and ability of a given level of SO2 to protect the wine is a different issue than whether or not a wine should go through MLF. For practical reasons and to keep sulfite levels in check, it is helpful to treat white wines with lysozyme to prevent MLF, if MLF is not desired.

In recent years I purchase CA grapes (hot climate) and have had to add tartaric to most grapes. If you are getting hotter climate grapes, MLF is probably not a good idea.

Even in this described circumstance it is still helpful to do MLF. The pH and whether MLF is desirable are completely unrelated issues. The taste of malic acid is not appropriate in red wine. There may be rare exceptions but I can't think of one. Adjust the pH and acid levels as much as you like with tartaric acid.