Mould growth on meat at freezing temperatures

Meat is usually spoiled by bacteria, which grow more rapidly than moulds. It is usually suggested that mould spoilage occurs mainly with frozen meat when the temperature permits growth of moulds but not bacteria. Moulds were thought to grow at —10°C or even lower temperatures, while bacteria cannot grow much below —2°C, the freezing point of meat. It has also been suggested that the reduced water activity of frozen media rather than the temperature per se may determine the minimum growth temperatures for moulds. Examination of meat spoilage moulds showed most to be moderately xerotolerant with minimum growth temperatures of —5°C or higher. In only one species was growth limited by reduced water activity rather than temperature. During prolonged storage at —5°C, meat developed a flora dominated by yeasts. Visible mould colonies did not appear until the eighth month of storage. It therefore seems that most cases of mould spoilage arise when the temperature of meat surfaces approaches 0°C with surface drying inhibiting bacterial growth.