Tue Apr 02, 2013 1:12 pm
What temperature were you fermenting? How long did it stay on the yeast? How much DAP & nutrient did you have in the must? When did you notice the H2S gas?
Without getting into the full biochem discussion, you have a higher risk of forming H2S gas in the cider from these:
~ Yeast nutrient deficiency (Nitrogen, Pantothenate, Oxygen) = yeast produces more sulphide than it needs which forms as H2S gas - look at the Fermaid K and DAP additions (staggered similar to mead)
~ Too much Nitrogen (yeast metabolizes too fast- stagger nutrient additions, don't chuck it all in at the beginning
~ Wild yeast contamination
~ Higher fermentation temperatures (yeast stress)- look into cooler fermentation temps 59F to 64F
~ too much free SO2 in the must - test your must, the SO2 level needs to be less than 80mg/litre = limit your campden tablets to 1 per gallon (prefermentation) or 2.5 grams per gallon
~ Yeast autolysis - left on the lees too long (more than 2 days is pushing it)
~ when the must is 2-3 degrees Plato from being finished stir up the lees - this will help avoid redox at the bottom and control H2S production
NOW that the H2S is in your cider, CO2 flush as the others have stated. A Potassium Caseinate fining can be used. Also activated carbon filter.
Corporal, BN Army
On Tap: Whatever IPA, Oat Stout, Cider, Citra-Mosaic Hopped Cider, Cherry Cider.
Aging: Black Currant Lambic, Oud Bruin, Eng B-wine, 65gal barrel of scabby 3rd runs w/Rosalare-Lacto Brux -we just call T.E.D.