lol..co fermenting is when you start MLF while the wine is still actively fermenting in the alcoholic fermentation stage, I've talked to some experienced wine makers that started their MLF anywhere from 18 brix down to 5 brix.
Here is an interesting MLF story:
I started several batches of wine in the fall of 2012, as soon as the wine was fermented to dry, in this case .992, I started MLF (obviously a red wine) using VP41, after 2 months I tested all of my reds and the Chromatography test indicated that they had all completed MLF, at this point, I racked and stabilized the wine and set them to bulk age for 6 - 8 months in carboys, racking as needed until they were clear.
I followed by rotating these batches of wine into my barrels, the plan was to barrel age them for up to 6 months, I tasted a sample, and although the smell and flavor were great, it had a slight effervescence of sparkling wine, not as carbonated as a sparkling wine, but you knew it was present, I chalked it up to the wine needing to be degassed, and moved on to racking it to the barrel.
The norm for me is to taste a small sample of wine each time I have to top off the barrels to see how they are progressing, and to see if any off odors have developed. Over the course of a few months, every time I tasted the wine, that slight carbonation was still there, I figured that I was going to need to degass the hell out of this wine.
At one point, before I purchased the Vinemetrica SC-300, testing the SO2 levels was such a pain in the arse and highly inaccurate in my opinion that I must have either blatantly avoided testing the wine or forgot to, either way, on the next topping off, the wine smelled like rotten eggs...grrrrr.....I tried splash racking a few times before treating it with Reduless to correct the problem.
The wine seemed a bit stripped, it lacked the tannic characteristics that I look for in this wine, so I started adding tannin riche in small doses until it reached the level I liked.
Fast forward to last week, approx 15 months after starting the wine 13 months after the Chromatography test indicated that MLF was complete and the wine still had that damn light carbonation... I had to test 4 batches of wine and I figured, what the hell, test this one as well.....the test result showed that there was still a fairly good amount of Malic acid in this wine?!
So this wine has been slowly going through MLF for this long? Trust me, I made sure that I ran yet another Chromatography test on this wine two days later and it still showed the same results.... the only thing that I can think is that it has been in my cellar the whole time, which stays cool all season, it is odd, I've added meta several times over the course of the 15 or so months.
Moral of the story.... I have no idea, I thought that it would be interesting to let everyone know that I have a very persistent MLF...lol