Bottom line: I plan to put apple juice on a yeast cake, and I have three questions, regarding: pectic enzyme, juice OG, and yeast nutrition.
I have a 1.050 OG spiced brown ale on its third day in primary. The WLP 013 (London Ale) fermented very violently (half of a 5L [1.035] starter), and krausen rose and fell in the first 48 hours (at 68 degrees, though in room 62 deg. F ambient). On day 6, I will rack to secondary.
I want to put high-OG apple juice on the WLP 013 yeast cake in a 6.5 gallon carboy.
I have 5 Gallons of Kroger no-preservative, pasteurized (with Vitamin C) apple juice. I also plan on putting 6x 12oz. frozen apple juice concentrate (Kroger, again; no preservatives, and plus Vitamin C) into the 5 Gallons of juice prior to pouring on the yeast cake.
I may heat a gallon or two of the apple juice to less than 100 degrees, in order to add the frozen concentrate and end up around 70 degrees, and then add that volume to the three or four gallons of 62 to 65 degree juice that will have been already poured onto the cake in the carboy.
The questions: Pectic Enzyme: I have never used it. I have made a couple of batches of Graff, but I have not done a cider. I have read recommendations to add it at least 12 hours prior to adding to the yeast, but seeing as the juice is pasteurized, and I have no plan to boil the juice, so I would prefer to not break the seal on the juice 12 hours before adding to the carboy. Would adding the pectic enzyme during the aforementioned heating/concentrate melting step bee too close to the addition to the yeast cake, if the plan is to add that mix as soon as the concentrate is melted? When should I add the pectic enzyme? The fermentation will likely be fast and violent. Does yeast/fermentation have adverse effects on pectic enzyme, or vice versa? I am just looking for those with pectic enzyme experience to "chime in" on this question.
Next: Will 5 gallons of juice (at approximately 1.048-1.050 OG), when added to 6x (12 oz.) cans of juice concentrate, give me an OG worth throwing on a yeast cake? I cannot seem to find any extimate of gravity points added by a single can of 12 oz. juice concentrate, so I don't know if this will be doing a lot, or not much. Again- experienced input on this matter would be appreciated.
And finally: Seeing as this is an ale yeast cake, will adding the above quantities of juice require any special yeast nutrient? -If so, I have some; but with the cake being there, new, and relatively fresh, will I need to support reproduction? Will it be necessary to support the fermentation, or yeast metabolism? I am only asking, because I have only done Graff before, and the added malt sugars/extract obviated the need for additional yeast nutrients.
Oh- yeah- yeast nutrient was already added during the brew of the beer that yielded the yeast cake in the first place, if that helps.
I thank you for any input or interest in my questions. I appreciate it!