Foam is related to:
-The quantity of particulates in the juice, cider and especially cider from a grinder is “dirty “
-The type of molecules the yeast excrete, 71B is rated as low foam, some yeast will have foam equal to the liquid volume
-Total solids, apple juice is similar to grape, if it has waxes or or oils it will foam more
-temperature, a slower ferment builds up less foam