Malolactic Fermentation - are there risks ?

[freddie]

The last MLF thread was great. So as to not disrupt that line of thought I've posted my concerns here.

My experience is limited to the last 3 vintages, and haven't had the confidence to do a Cromatograhy test yet. I never really know whether it's actively working or not.

I understand now that it is necessary to regularly stir the lees into action in the early stages of MLF. And also to continue to stir the lees during the whole MLF stage.

So I have a variable capacity tank which means that every time I need to stir the lees, I have to remove the lid completely to do so. Am I not regularly exposing the wine to air each time I do this. Given the low levels of So2 that are present in the wine at this stage, is there a greater risk to oxidation if the MLF is not actively working.

I my case, there are never any visable signs that there is a Malo taking place. So am I taking excessive risks with my wine by proceeding in this manner.

 

[grapeman]

Of course there are some risks, there always is. However if you take some precautions you lessen those risks considerably. You should be checking the pH and TA of the wine before beginning mlf Once you know those you have the information needed to choose a proper ml bacteria. They work within certain ranges so if you choose a proper one then it is more likely to proceed without problems. Also consider the temperatures in the winery. Some work better at cool temperatures than others. After choosing the mlb, then see what the manufacturer recommends for proper nutrient for the bacteria. After getting all those things in hand prepare the bacteria as per directions from the company. Dose the wine with recommended nutrient. Pitch the prepared mlb into the prepared wine and give it a bit of a stir. Seal the tank and the mlf should soon propagate and begin an active malo lactic fermentation. While you can stir the wine every few days, you might want to consider making a pump over setup to stir the wine without opening the tank cover. You probably have a valve at the bottom and an airlock at the top. Get creative and with some hoses and maybe a sureflo pump, you can circulate the wine to stir it up. You really should get set up with some type of test for the mlf. You can use an Accuvin test, chromatography or even the newer Vinmetrica test.

This is just some of the basics, but should give you some ideas to ease your mind.

 

[grapeman]

Freddie,


Grapeman,

were my concerns about the sediment valid? Does stirring the lees twice per week set back the clarifying process? Would you consider those 4 months somewhat lost as far as clarification and settling of the sediment?

No the worry is not valid. Sediment is sediment and will drop out soon after stirring is complete. What doesn't clear quickly is any type of haze, be it protein or pectin. 4 months without mlf being active could be a worry since no gasses are being produced to protect the wine. If it did not work for a long time it may have been low temperatures. The low temps would protect the wine some though so not a big concern.

 

[freddie]

Grapeman, I note your comments with interest.

I also used VP41 and I have not heard of any other types of ML bacteria. Most guys use VP41. This year I did not use a nutrient but note that my temp. sits at around 64 deg. F.

Is it too late to use a ML nutrient - it's been about 3 weeks now (22 Mar 15) that I pitched the VP41.

I checked my pH readings and note that both Shiraz and Merlot were at 3.55. So2 addition at crush was 50ppm.

Also, at what stage can you stop stirring the lees during the MLF period. And how long should the MLF process take with lower temperatures. around

 

[freddie]

fermentation. While you can stir the wine every few days, you might want to consider making a pump over setup to stir the wine without opening the tank cover. You probably have a valve at the bottom and an airlock at the top. Get creative and with some hoses and maybe a sureflo pump, you can circulate the wine to stir it up. You really should get set up with some type of test for the mlf. You can use an Accuvin test, chromatography or even the newer Vinmetrica test.

This is just some of the basics, but should give you some ideas to ease your mind.

I am also interested in your reference to the "sureflow" pump. Is this a
gentle and slow type of pump ideally suited to this task ?. It seems to me that such a system is a lot easier than removing and replacing the VCT top each time.

Those tops are a bugger to get re-sealed as on the fluid, they squeese out the juice, so adjusting the height each time by one's self is a real bugger. Maybe I'm not approaching it correctly. Any thoughts.

 

[grapeman]

See the following little booklet from Scott Labs for some good info about the processe of mlf. http://www.scottlab.com/uploads/documents/downloads/318/ML%20Brochure.pdf
Presque Isle carries a few mlb strains and starter/nutrients. 64 degrees is pushing the temperature of VP41 a bit since it is on the low end of the range. If you could bring it up to about 70, it would complete quicker. Stirring does not need to be every day but fairly often helps.

The sureflo pump is a small electric diaphram type pump so is self priming and fairly gentle on the wine. They come in either 110V or 12V and need to be wired accordingly. Here is one example link http://www.northerntool.com/shop/to...Sj1SbiTiwNMbx8CxcJF8-DRJv70_kTsxiYRoC9nTw_wcB

 

[freddie]

Grapeman, great brochure from ScottLabs on MLF. A quick read and I've learnt a lot already. I will keep this close. Thanks again.

Regarding the Shureflow pump, looks like a nice unit, but you may have gathered that I'm not in the US. What is important about this type of pump for the MLF pump over technique - is it the flow rate (1.8LPM) or the pressure(60PSI).
I have no mechanical or engineering mind, so some guidance on the critical factors would be greatful since I will have to source a similar unit locally.

On a side note, can you suggest any other practical usages for such a pump in the winery. I already have a few good transfer pumps.

 

[grapeman]

That is just one example of a pump that is easy on the wine. It will move the wine at a fairly slow rate which will just work to circulate the wine gently. There are many models of that type with varying flow rates. If you already have a pump it would probably work alright unless it is a large pump that beats up the wine. All you want to do is pump the wine from the bottom of the tank to the top without introducing a lot of air. I am also assuming a fairly large tank to justify this setup. If you have a tank 4 to 10 feet deep it is hard to stir the wine with just a small dowel or spoon. If you are talking a small tank there are certainly easier ways. I am merely offering a way to do it without letting in a lot of air.

 

[Turock]

I think FAR too much attention is being paid to stirring an MLF in a tank, let alone running it thru a pump!!! You do not have to stir it. The MLF will complete fine on its own without stirring. My advice is to just leave it alone.