Some of the Konbu that I recently bought has a whitish discoloration as opposed to a black/green color. I am wondering if it can still be eaten/used in cooking. Konbu
This is perfectly normal. Many people believe the flavor is most concentrated in those crystallized bits. Embrace it!
In fact, you want to avoid washing off the konbu before using it so as not to lose the white powder, which results from natural, slow, drying.