Stubborn Cider Fermentation
Q: I've been home brewing beer successfully for several years now, but I tried my hand at making my first batch of hard cider a few days ago with really rotten results. I am hoping you can help me diagnose the problem. The recipe below was taken from a magazine article, with a few minor modifications.
Recipe
14 12oz cans of frozen apple juice concentrate
2.5 lb clover honey
12 oz safflower honey
1 T ground cinnamon
2.5 tsp acid blend (acid content of the must after adjustment was 0.55)
5 tsp yeast energizer
1.5 tsp potassium metabisulfite (to sterilize the must)
2 pkg dry wine yeast (Cote des Blancs)
Tap water to make 5.5 gallons
Original gravity: 1.065, adjusted to 60° F (16° C).
My procedure was as follows. First, I boiled the honey in about 1 gallon of water for about a half an hour, skimming the top layer as it arose. I then chilled the honey water, added it to the apple juice concentrate in my carboy, and topped off the carboy with tap water to make 5.5 gallons. I then measured and adjusted the acid level to my liking, after which I added the cinnamon. At this point the must tasted wonderful.
Next I added the potassium metabi-sulfite to the must and let it sit under a fermentation lock for 24 hours. The next day I aerated the must well with my aquarium pump. I then rehydrated and pitched the yeast, added yeast nutrients, reattached the fermentation lock, and smiled with contented anticipation.
When I checked in on my tasty concoction 24 hours later, however, I saw no signs of fermentation. My first reaction was that the yeast may have been bad. I promptly went down to my favorite homebrew store and purchased two additional foil packages of Munton & Fison ale yeast. I've never had a bad batch of beer when using Munton & Fison yeast, so I was hopeful of saving my cider at this point. When I got home I added an additional 1.5 tsp of potassium metabisulfite to the must in case any wild bugs got into it, and I let it sit under a fermentation lock for another 24 hours. The next day I aerated the must again, added more yeast nutrients, rehydrated and pitched the ale yeast, and attached the fermentation lock.
The morning after pitching the ale yeast -- still nothing. Nor did I see any sign of fermentation when I came home later that evening, nor the day after. The whole batch was a loss. I did notice something interesting, however: sitting on the bottom of my carboy was what looked like a half inch of yeast sediment. It appeared to me that maybe the yeast initially grew in the presence of the oxygen and yeast nutrients, but somehow was unable to ferment the sugars in the must. Is this possible?
I checked the fruit juice concentrate to see if it contained any preservatives that could have killed yeast. There were none. Is it possible that the vitamin C in the concentrate could have inhibited fermentation? Were the sugars in the fruit juice too complex to ferment? I also wondered about my having used tap water instead of bottled water. I usually use bottled water when making beer because my local water is rather hard and I believe it has reduced my all-grain extract efficiency on some occasions, though it has always served well enough for extract brewing.
Another possibility is that I somehow sulfited the must improperly. Should I not have used a fermentation lock at this point? I had assumed that my vigorous aeration would have "scrubbed" away any harmful gasses produced in the sulfiting process.
A: Two culprits are likely here: sulfur dioxide (SO2), which is the bacterial inhibitor/antioxidant produced by your sulfite, and additives in your must ingredients. Sugar is not an issue. Fruit sugar is mainly fructose, a simple sugar, and honey is mainly invert sugar. Yeast has no trouble with either one.
I tend to agree with you that a vigorous aeration should scrub out the SO2, so that seems the least likely explanation. Still, it's hard to be sure. Next time you try cidermaking omit the sulfiting and pitch your yeast right after aeration.
You mention the lack of additives in the juice. But the can says "apple juice from concentrate." What was in the concentrate? I don't know that much about labeling laws, so I don't know whether the manufacturer could have spiked the concentrate without reporting as much on the label of the finished product. Also consider your honey. I once tried to make a batch of mead using grocery-store clover honey, and I could not get it to ferment. The label said nothing, but I am convinced it contained some antifungal additive(s).