Why do turnip greens and kale taste better after a frost?
A. When winter temperatures arrive, hardy greens try to protect their leaf tissues from freezing by converting some stored starch into soluble sugars. The presence of the dissolved sugar lowers the temperature at which the plant sap will freeze by several degrees. When the sap or juice in the these plants does freeze, it expands and ruptures cell walls and other structures, often killing the plant. We generally prefer the flavor of the greens with the increased sugar content.