EFFECT OF TEMPERATURE AND HUMIDITY ON COLOUR OF LEAN, AND DEVELOPMENT OF RANCIDITY IN THE FAT, OF PORK DURING FROZEN STORAGE

Abstract

Pork cuts were stored at relative humidities of 83, 87, 92, 96, and 100% and temperatures of − 6.6°, − 12.2°, − 17.7°, and − 23 °C. for 48 weeks. Visual examination revealed various degrees of surface drying under all conditions, and pronounced methaemoglobin formation at − 6.6 °C. Quantitative colour measurements on both the exposed and internal surfaces of the lean, showed that storage temperature was the primary factor affecting the colour. Temperatures of − 18 °C., or lower, are required to prevent these changes. Samples that had suffered the greatest colour change during storage showed the least change during subsequent exposure.Temperature was also the primary factor affecting the development of rancidity in the fat. Both peroxide oxygen and free fatty acid increased significantly with increase in storage temperature, particularly between − 12.2° and − 6.6 °C., but the actual quantities of free fatty acid were small and of little consequence. Storage temperatures of − 18 °C., or lower, are essential if spoilage of pork fat is to be avoided over storage periods of approximately one year's duration.