zucciniflower...i found this about cooked apples:

Even though quercetin is relatively stable during cooking, fresh apples are better sources of quercetin than cooked or processed apple products because the compound is mainly concentrated in the skin of apples rather than the flesh, Lee says. Products such as apple juice and apple sauce do not contain significant amounts of skin. In general, red apples tend to have more of the antioxidant than green or yellow ones, although any apple variety is a good source of quercetin, he adds.

http://www.eurekalert.org/pub_releas...s-ia111604.php

hope this helps. doesn't say how much it's reduced.