Mushrooms remain very active after harvest compared to most produce, and may even continue to grow. During four days’ storage at room temperature, they lose about half of their energy reserves to the formation of cell-wall chitin. At the same time, they lose some of the enzyme activities that generate their fresh flavor, while protein-digesting enzymes become active in the stalk and turn the stalk proteins into amino acids for the cap and gills; so these parts become slightly more savory. Refrigeration at 40–45°F/4–6°C will slow mushroom metabolism, but they should be loosely wrapped in moisture-absorbing packaging to avoid having the moisture they exhale wet their surfaces and encourage spoilage. Mushrooms should be used as quickly as possible after purchase.