Michael D. Kalaras is a Post-Doctorate Scholar in Penn State's Food Science Department.

Exposing mushrooms to constant ultraviolet light will increase the level of vitamin D -- but, as this photo shows, it makes the mushrooms brown and causes discoloration, which may be unappealing to consumers. A technique developed by Penn State researchers uses fast bursts of ultraviolet light to quickly increase vitamin D without discoloring the mushrooms.