Enzymic activity at low moisture levels and its relation to deterioration in freeze‐dried foods

Loss of glycogen occurred in two different model systems containing enzymes from meat, when they were stored at humidities comparable to those of freeze‐dried foods. The losses were much greater in experimental samples than in controls in which the meat extract was either boiled or absent. The fall in glycogen is attributed to enzymic activity which seems to persist at 3% moisture content and perhaps even lower. Enzymic activity at such moisture levels could explain the sensitivity of raw freeze‐dried foodstuffs to moisture level during storage and the insensitivity of precooked freeze‐dried products.