increasing esters in beer
We have moved most of the production of our biggest seller, an American pale ale, to our 30 and 40 bbl tanks, which take three and four batches to fill. I've noticed differences in the final beer between our 10 bbl unitanks and these multiple batch-sized tanks. For one thing, the final gravity is about 0.5 plato lower in the bigger batches. Also, the larger batches don't seem to have the same ester profile - our english ale yeast developes a nice apricot, lemony ester in the 10 bbl batches that seems subdued in the bigger 30 and 40 bbl batches.
What are some good ways to manipulate the fermentation to get the same ester profile? I am thinking of trying to change temperatures, oxygen content, and pitching rates. We ferment at the same temperatures, and pitch the same proportion of yeast per barrel. We only apply oxyegen on the first two batches during the first 12 hours, not on the next one or two batches that finish filling the tank the next day.