After really enjoying a bottle of Neige Ice Cider awhile back I decided to try my hand at making something similar this fall. Ice cider is much closer in character to an ice wine than it is to a regular hard cider (which many people liken to champagne). Ice Cider is rich, sweet, alcoholic, not to mention expensive.
Here is the designation reserved for ice cider in Quebec from Wikipedia:
« Cidre de glace » : "Cider ice" drinks produced by the fermentation of apple juice, which must have a concentration of sugar before fermentation made solely by the natural cold of at least 30 Brix and whose product has a residual sugar content of at least 130 grams per liter. Finally, the alcohol will be obtained over 7% and less than 13% alcohol by volume.
That is to say that the cider is frozen to concentrate the OG above 1.129, and the real residual extract is above .053. According to their website the bottle of Neige I had started at 1.159, has .060 of residual sugar, and 12% ABV (surprisingly similar numbers to Dark Lord Russian Imperial Stout from 3 Floyds).
A word about the legality of all this, what we are talking about here is not a form of distillation (as in making a Cider Jack or Eisbock). I am condensing the natural sugars the cider contains before fermentation. This is equivalent to boiling beer wort to condense the sugars before fermentation. The idea is to get enough sugar to go above the alcohol tolerance of the yeast and still have a pleasant amount of residual sweetness. If you froze a regular batch of cider it would get strong (stronger than ice cider), but it would still be very dry.
I started with 6 gallons of regular fresh/local cider (pasteurized, but preservative free). I added 1/2 tsp of pectic enzyme to each gallon. After allowing the enzyme to work on clearing the cider for a few hours I racked the cider into my bottling bucket. I then put it into my chest freezer which I had set to 20 F. It took just 24 hours to freeze the cider into a thick icy slush. I left it there for the next few days, because the freezer cycles +/- 3 degrees I was hoping this would be enough to let the sugary portion of the cider separate from the frozen water.
I took the bucket out of the freezer and tried to open the spigot hoping that like a frozen pond the ice was simply a layer on top of the cider. Sadly a ring of ice had formed around the edge of the bucket rendering the spigot useless. However, under 1/2 inch of ice the middle column was still liquid so I poured this portion out through a metal strainer. This yielded about 1.5 gallons of 1.082 cider (a 60% increase over the original juice). Not quite as strong or as much as I was looking for, but not a bad start.
Over the next hour the frozen cider slowly melted releasing more concentrated cider before the rest of the water (you can see how clear the ice the top got). I was able to pour off another .5 gallon of cider. Sadly at this point my apartmentmate decided it would be funny to put a slice of turkey on my shoulder as I bent over the bucket... as I was removing the offending meat it fell right into the cidery slush. I decided the risk of microbial invaders was enough that it wasn't worth continuing my extraction.
I was hoping to get 3.5 gallons of 1.082 cider which I could freeze again. Assuming another 60% gravity increase I would have been right at the 1.129 "minimum" original gravity.
With only 2 gallons to work with I decided that it would be simpler to just ferment it out as is. So after letting the cider warm up to 60 degrees I gave it a shot of oxygen, some yeast nutrient, and the yeast slurry from this year's batch of normal cider (nothing but cider, pectic enzyme, and Wyeast's Cider yeast).
Hopefully next fall I'll be able to put what I learned this time to use (namely to lock the door when I am working with the slush).
Cider Slurpee
Recipe Specifics
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Batch Size (Gal): 2.00
Anticipated OG: 1.082
Anticipated SRM: 13.2
Wort Boil Time: 0 Minutes
Cider
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6.00 Gallons Cider
Extras
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0.50 Tsp Yeast Nutrient
3.00 Tsp Pectic Enzyme
Yeast
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WYeast 3766 Cider
Notes
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11/30/08 Bought 6 gallons of cider, added 1/2 tsp of pectic enzyme to each and set the freezer to 30. After a few hours I racked them into my bottling bucket and set the freezer to 20.
12/04/08 Tried draining it through the spigot, but just got a trickle. Sliced up the ice with a knife and poured it through a strainer. Let it sit several times to melt a bit more. Gravity was a bit short of where I wanted, but not too bad (~1.082).
Let it warm up a bit then gave each jug a 30 sec shot of O2 and 1/2 cup of yeast slurry from the standard cider.
12/09/08 Down to 1.006 (93% AA, 10% ABV)
1/24/09 Bottled with 1 7/8 oz of cane sugar plus a few grams of EC-1118 Champagne yeast. Aiming for 3 volumes of CO2, hoping for more of a Champagne feel.
9/30/09 First Tasting, really coming along nicely.