Originally Posted by Yooper
Sometimes a cidery flavor can come from a too-warm fermentation temperature also.
Right. If the temp of the fermenting liquid gets into the 70s, then acetaldehyde production skyrockets. Acetaldehyde is what produces those green-apple like flavors.
Chris White (White Labs) in his Yeast book did an experiment with a pair of 5 gallon batches, one fermented at 68 and another at 75. I don't remember the exact numbers off the top of my head, but the 68 degree batch produced something like 7-9 ppm of acetaldehyde (with an 8-10 ppm taste threshhold), while the 75 degree batch produced something like 150 ppm.
Try cooler fermentations and see if that doesn't solve the issue.