Photo/Art by Brenda DarrochPlease settle a dispute: my friend says the best mushroom caps are the ones that are tightly closed and that open ones will spoil much sooner. I say bigger is better. Who’s right, and can you tell me how to choose fresh mushrooms?
It depends on the mushroom, but I’ll assume you’re talking about white mushrooms, cremini, and portobellos, the types most common in grocery stores. With these, a tightly closed cap means the mushroom is immature, though it may be full-size. As time goes on, the cap expands, the gills darken, and the flesh softens as it loses moisture. This makes it sound as if you lose, but that isn’t so. Whatever the variety, a mushroom will have its richest flavor after the cap has flattened out some and spoors (which grow on the gills) have had time to ripen.
Closed or open, mushrooms will keep for about the same length of time — three days to a week — as long as you do not smother them in plastic. They want a cool, slightly damp atmosphere with plenty of air circulation. Put them in one layer, gill side down, on a plate covered with a barely dampened paper towel or put them in a basket with the toweling in the bottom. Cover loosely with waxed paper and store refrigerated.