This years batch is a bit of an experiment, but one which came out fairly well. To backtrack a bit, last year I prepared a batch of cider which I allowed to ferment using only the wild yeast present in the cider. This cider was good, but not great - it was extremely dry, and the earthy/musty flavour was a little more intense than SWIMBO would prefer (I liked the strength of it, but I brew cider for her, not for me).
This year I took a hybrid approach, to get the higher complexity of a wild ferment while restraining the wild character to a more modest level.
The one issue I ran into this year was the raw cider itself. The cidery which sells my brew club cider produces raw cider for local grocery stores. As a consequence, they do not worry about the blend of apples used, so long as the sweetness falls within a specified range. With alcoholic cider making, professional cider makers will use deliberate mixes of different types of apples to get a proper sugar content, while making sure that the amount of residual tanins and acids are appropriate to lend the fermented cider a nice balance. The cider we received this year was very sweet (O.G. of 1.052), and was clearly made almost entirely of dessert apples as there was almost no acidity or tanic character to the raw juice. As a result the fermented cider was quite dry, thin bodied, and somewhat weak tasting - issues I addressed by an alternate method of back-sweetening which was a smashing success.
Details & tasting notes below the fold.
The brewing of this cider was quite simple - 20L of raw cider was combined with 3 g of potassium metabisulfite and left to sit for 12 hours. This kills off any residual wild yeasts or bacteria, allowing me to specifically dose in the yeast and bugs I want. At the 12-hour mark I added a sachet of pectic enzyme (intended for 23L of wine), and let the cider sit an additional 12 hours. At this point I added my go-to cider yeast (Nottingham), plus a 1-cup starter of the wild yeast/bug harvested from last years wild cider. This was left at room temperature for 2 weeks to ferment.
14 days after pitching the yeast, the cider was transferred to a fresh carboy and moved to our cellar which sits at 12-16C. It was allowed to sit, undisturbed, for 1.5 months during which time it developed a bit of a pelicle and developed a small degree of haze. At the 1.5 month mark I added chitosan/klenisol (clarifying agents usually used in wine making), and let the carboy sit for an additional 2 weeks.
At this point the cider was clear and tasting clean. But, as mentioned above, the acidity and body of the cider was lacking; it was also extremely dry, to the point that even I - a lover of dry cider - thought it was too much. To fix this the cider was transferred to a keg and stabilised by the addition of 2.5 teaspoons of potassium sorbate and 1/4 teaspoon of potassium metabisulfate. I then added a single packet of reserve juice I didn't add to a batch of Gwerztraminer wine to backsweeten and provide a little more body, sweetness and acidity. The keg was then force carbonated.
Appearance: As you can see from the above image, the cider is a very pale straw colour, highly effervescent, and pours with a course white head which persists for several minutes.
Aroma: Strong aroma of apples; most similar to a gala-type apple. A very slight mustiness (earthy/leather) sometimes comes out in the aroma.
Flavour: The flavour of this cider is excellent. It has a modest apple character, well balanced by a touch of sweetness, with a subtle earthy-funk from the wild yeasts adding a touch of complexity. The acidity of the cider is very low, to the point it is a noticeable flaw. Aftertaste is apple and a touch of sweetness.
Mouthfeel: Airy, light and effervescent - everything a cider should be. One of the more refreshing beverages I've ever had on-top.
Overall: I think this is the best batch of cider I've ever made, although my 2014 vintage would be a close second. The balance of flavours is fantastic, other than the lack of acidity. But even with this minor flaw, I'm quite happy with the way this cider turned out.
The low acidity is likely a product of two factors - the initial low acidity of the must, and the fact that I left the cider on its lees for 1.5 months. This can greatly reduce acidity in a cider, as lactobacilli in the lees will ferment malic acid (which has a strong acid character) to milder lactic acid. This decreases the acidic sensation of the cider, but can easily be limited by transfering cider off of its lees a week or two following transfer to secondary.