Building on last year’s experiments, here is what I’ve learned so far for this year (10 keg batches and 17 experimental gallon batches):
Juice – Mark from ABS Brew clued me in to why the pasteurized juice did not keep as well as unpasteruized. Two reasons. First, potasium metabisulfite does not just kill the wild yeast. It is also a preservative. Second, UV pasteurization reduces ascorbic acid, which also acts as a preservative. This is also why the unpasteurized juice is much more tart when it finished fermenting.
Based on that info, I tried a few batches of unpasteurized juice, with and without adding the K-meta. They have been going about a week and I checked them yesterday. SGs have dropped from 1.060 to 1.014, so they still have a way to go. At this point, the batches without the K-meta taste much better. They have a natural apple taste and would be quite drinkable right now, although I am planning to let them go another day or two and cold crash around 1.004. The ones with the K-meta have a tart candy apple taste that is very familiar – I expect these will be quite good in a few months, but now, not so much.
I’ll be starting some more keg batches in a couple of weeks and will definitely cut back on the K-meta – maybe use half the recommended dose. I’m also planning to start a new round of single gallon experiments to see if there is an optimal amount of K-meta to add to kill the wild yeast without turning the must sour. I was planning to use k-meta to stop fermentation on the keg batches which are currently in primaries, but now that I know the effect on the taste, I’m going to cold crash instead.
Yeast – I tried several new yeasts. Juice was unpasteurized Stayman, Empire and Golden delicious, with a bit of Granny Smith. All were fermented at a temperature range of 60-65 degrees. All of the new yeasts fermented out much faster than the Nottingham and SO4 ale yeasts, which I used as a control. After 7 days, the Nottingham and S04 batches were all at 1.014. Keep in mind that gallon batches tend to ferment out faster than 5 gallon batches, so add a couple days if you are doing a 5 gallon batch. I added K-meta to the juice 24 hours before pitching the yeast, so its going to be a month or two before any of these are really good, but here are first impressions, in order of potential:
Lallemand Munich wheat – Cold crashed 7 days after pitching yeast. SG was at 1.002. Has a good apple taste, with a bit of clove and k-meta tartness
Brewform Lager – Cold crashed 7 days after pitching yeast. SG was at 1.004. Good apple taste, with some interesting flavors I cant quite put my finger on – still dominated by tartness of k-meta
Enoferm ICV-D47 – Cold crashed 6 days after pitching yeast. SG was at 1.010, but the taste was very dry and smooth. The k-meta taste wasn’t as prominent.
Coopers Ale – Cold crashed 7 days after pitching yeast. SG was at 1.004. Not bad. I tried this yeast before with pasturized juice and was not impressed, but with unpasteurized it is pretty good.
Saflager W34/70 – Cold crashed 7 days after pitching yeast. SG was at 1.000. It was a little too dry for my taste, but may improve after k-meta wears off.
Lalvin 71B – Cold crashed 6 days after pitching yeast. SG was at 1.000. Overly dry, but has a decent finish
Munton Ale yeast – Cold crashed 7 days after pitching yeast. SG was at 0.998. I should have caught this one sooner. I tasted it at 6 days and it was pretty good, but at 7 days it had lost a lot of flavor.