Malolactic Fermentation

[dpambianchi]

One of my great interests in enologyis malolactic fermentation (MLF). One of the great debates in MLF is the timing- that is, pre-,co-,vs post-fermentation - as well as indigenousvs cultured bacteria. I know the theory and then I've done my own controlled experiments. The results were quite surprising. Timing and type of bacteria can make an amazing difference in the wine profile. Although at my winery we always inoculate with cultured bacteria and as soon as the alcoholic fermentation has completed, in my experiment with Cab Sauv, my favorite was the cofermented one with ... indigenous bacteria. We're not talking subtle differences here, but rather, a substantial difference that would throw any enophile off.


I'm interested to know how some of you do and what has been your experience.

 

[Skyhawk]

I would imagine indigenous bacteria to be a hit or miss affair, since I think I read that some lactic acid bacteria can impart off flavours. Then again, even when inoculating, how does one know that MLF isn't later occurring with a mixture of bacterial strains that were already there? Correct me if I'm wrong, but the typical amount of SO2 added after crushing/at pressing will just inhibit wild lactic acid bacteria, but not kill it?

But that's interesting about the difference with your wild MLF and cofermenting. You need to isolate the strain!

Oh, I have a long-ago-neutral "mystery MLF barrel" that's pretty good. A microbiologist might have a field day identifying the wildlife in it though.

 

[grapeman]

I have always done a post MLF, but then I haven't done a ton of them yet. It is easier to control the conditions while innoculating than relying on indigenous strains. After saying that however, I had a number of carboys of Leon Millot that had finished up fermentation and I was trying to decide if I wanted MLF on them or not. By itself Millot isn't all that complex, so even though acids were tolerable, I was considering if I wanted to do it or not. While I was deciding, we had a few warmer days and it decided to start up on it's own. I figured what the heck, I will let it run it's course and see what happens. I fed it some opti-malo and let-er-rip. It finished up a few weeks later so I decided to try it and see how it did. Wow, what a difference. It really added to this wine in complexity and mouthfeel. I would love to get this result every time. If only I could replicate the bacteria that started it!

 

[Jeff H]

A goodread is the work that Lallemand has done on Malolactic Bacteria related to selected versus spontaneous:
http://www.lallemand.com/oenology/Images/PDF/WinemakingUpdate/1-3Malobact.pdf


Interesting is thesidebaron Biogenic Amines on pg 1 and the table on page 2. This work seem to make a good agrument for selected innoculation of LAB.

 

[Skyhawk]

Enococcus oeni also metabolizes citric acid and creates (to excess) Diacetyl? And here I thought if the malic acid was used up we had stable wine!

Here is similar info, with tons of references:
<a href="http://%20www.newworldwinemaker.com/articles/view?id=245" target="_blank">
</a>http://www.newworldwinemaker.com/articles/view?id=245

Helps show the importance of pH when undergoing MLF, since inoculated LAB will be competing with more species of wild ones with a higher pH, as well as the info about Biogenic amines. Interesting about the VA too (acetic acid production).

 

[dpambianchi]

I would imagine indigenous bacteria to be a hit or miss affair, since I think I read that some lactic acid bacteria can impart off flavours. Then again, even when inoculating, how does one know that MLF isn't later occurring with a mixture of bacterial strains that were already there? Correct me if I'm wrong, but the typical amount of SO2 added after crushing/at pressing will just inhibit wild lactic acid bacteria, but not kill it?

But that's interesting about the difference with your wild MLF and cofermenting. You need to isolate the strain!

Oh, I have a long-ago-neutral "mystery MLF barrel" that's pretty good. A microbiologist might have a field day identifying the wildlife in it though.

Yes, you are absolutely right. The textbook way of carrying out MLF to get desired and expected results (and that means that the finished wine is microbiologically stable) is as follows ... for red wine:


1. Crush &amp; sulfite - the SO2 at this stage inhibits indigenous yeast and bacteria.
2. Macerate, ferment - at the end of fermentation, the SO2 should (will) be sufficiently low to carry out an inoculated MLF
3. Press &amp; transfer to S/S tanks or barrels
4. Add MLF culture
5. When MLF is complete, sulfite. Maintain a minimum FSO2 level (eg 35 mg/L) through aging and until bottling.
6. At bottling, STERILE FILTER.


This last step is usually not done by home winemakers because we are not equipped for it. Inmy book, Idiscuss how to do it. But this last step guarantees microbial stability of the wine while in bottle; otherwise, it risks going through MLF in the bottle. It should not be a problem though is the FSO2 is adequate.

 

[dpambianchi]

I have always done a post MLF, but then I haven't done a ton of them yet. It is easier to control the conditions while innoculating than relying on indigenous strains. After saying that however, I had a number of carboys of Leon Millot that had finished up fermentation and I was trying to decide if I wanted MLF on them or not. By itself Millot isn't all that complex, so even though acids were tolerable, I was considering if I wanted to do it or not. While I was deciding, we had a few warmer days and it decided to start up on it's own. I figured what the heck, I will let it run it's course and see what happens. I fed it some opti-malo and let-er-rip. It finished up a few weeks later so I decided to try it and see how it did. Wow, what a difference. It really added to this wine in complexity and mouthfeel. I would love to get this result every time. If only I could replicate the bacteria that started it!

One trick I learnt (but which I have never tried, and so I can't guarantee the results) is to save the lees from your MLF, freeze them, and re-use them in your next batch. The microbiologists won't support this but I know folks who have tried it successfully.

 

[dpambianchi]

A goodread is the work that Lallemand has done on Malolactic Bacteria related to selected versus spontaneous:
http://www.lallemand.com/oenology/Images/PDF/WinemakingUpdate/1-3Malobact.pdf


Interesting is thesidebaron Biogenic Amines on pg 1 and the table on page 2. This work seem to make a good agrument for selected innoculation of LAB.

Don't get me wrong; I'm a strong supporter of inoculated MLF. I just want to point out that there are various other ways of doing MLF. I give an overview in an article I wrote for WineMaker magazine for the Feb-Mar 2007 issue. I also wrote another one on wine microbiology for the Aug-Sep 2008 issue. I'll see with the publisher about making these available in this forum.

 

[dpambianchi]

Enococcus oeni also metabolizes citric acid and creates (to excess) Diacetyl? And here I thought if the malic acid was used up we had stable wine!

Here is similar info, with tons of references:
<a href="http://%20www.newworldwinemaker.com/articles/view?id=245" target="_blank">
</A>http://www.newworldwinemaker.com/articles/view?id=245

Helps show the importance of pH when undergoing MLF, since inoculated LAB will be competing with more species of wild ones with a higher pH, as well as the info about Biogenic amines. Interesting about the VA too (acetic acid production).

In addition to my reply to Jeff H, I will also try and make available a presentation Igave at last year's WineMaker conference in Sonoma on MLF. It's basically a home-winemaker version of work done in this area. Interesting stuff this MLF, eh? (I'm Canadian)

 

[Jeff H]

Daniel...I'd be interested in seeing those works. Hopefully the publisher will be accomodating. Thanks

 

[smikes]

Daniel,


As a side note, received your book as a gift this winter, and is very well put together.


Thanks for sharing your knowledge and welcome to the forum!

 

[AlFulchino]

ditto the welcome!