At the Co-op, Tofu, Kale and Cocoa Puffs.

NEW HAVEN DENNIS DANAHER is contemplating a wall of cereal boxes at Elm City Market here. ''They still don't have the cereal I like,'' he says, but rather than go elsewhere he chooses another variety. That loyalty should be good news to Mr. Danaher himself, since Elm City is a food co-op and he is one of about 1,600 people who own it. [ABSTRACT FROM AUTHOR]