Thursday, July 16, 2009

Chilean Syrah MLF

Loyal readers will recall that I've been working on a batch of Chilean Syrah this spring. Primary fermentation was complete on schedule, and other than getting a wine bath when I pressed, no big issues arose. We last left the wine after innoculation with malo-lactic bacteria and it's been doing it's thing ever since.

Interestingly, the two different batches of wine behaved quite differently after innoculation. The batch fermented with D80 yeast displayed the characteristic shower of tiny bubbles once the MLF (stands for malo-lactic fermentation, not the other thing, you perve) commenced. On the other hand, the batch fermented with D254 yeast displayed no bubble formation or any other sign that the MLF was in progress.

After about two weeks, I transferred about 2 cups of wine between the batches to try to get things going. The D254 batch finally started to display some bubble formation, but nothing to really brag about. Since then I've just let it sit while I tried to figure out what to do. After another couple of weeks (had other errands to take care of in the meantime), I ran a chromatography test and amazingly, both batches exhibited <100 ug/L malic acid. I was out of the Accuvin test strips that I prefer to use to monitor MLF, so it took another couple of weeks to finally order some test strips and receive them. Last night, the D80 yeast is at around 50 ug/L malic acid while the D254 yeast is around 75 ug/L. MLF is considered done when the level is less than or equal to 30 ug/L so both batches are slowly getting there. Very interestingly, the D80 batch is still producing a fairly steady stream of tiny bubbles, while the D254 batch only emits an occasional bubble. I'm going to let both batches keep going and will check on the progress in another 2-3 weeks.

MA Winemaker

p.s. Update on 7/19/2008: I was considering racking the D80 batch and stopping the MLF with a SO2 addition. In preparation, I brought the carboys into the kitchen from the garage on 7/16. As soon as I did that, the MLF seems to have kicked into high gear and almost started bubbling out of the carboy. Had to remove a little wine to prevent overflow! The kitchen is cooler than the garage, so I'm assuming that the motion of carrying the carboys inside helped to mix the wine in the carboy and brought the residual malic acid in contact with the bacteria for easier metabolism. Bubble formation seems to have stopped or greatly slowed this morning, so I'll test tonight and see if MLF is complete.

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