Structure of beef Longissimus dorsi muscle frozen at various temperatures: Part 1-histological changes in muscle frozen at -10, -22, -33, -78, -115 and -196°C.

To elucidate the relationship between the lowering of freezing temperature and the distribution of ice crystals in frozen muscle, samples of beef Longissimus dorsi muscle were frozen at -10, -22, -33, -78, -115 and -196°C. Histological preparations of these samples indicated that ice crystals were formed in muscles frozen at -10°C intercellularly, at -22°C inter- and intracellularly, at -33°C intercellularly and at -78, -115 and -196°C only intracellularly. In muscles frozen at -78°C, ice crystals in fibres were large; in those frozen at -115°C they were relatively smaller; and in those frozen at -196°C they were evenly distributed throughout the muscles. The greatest damage was caused at -22°C due to the simultaneous formation of the ice intra- and intercellularly. The results indicated that the pattern of distribution of ice crystals at the latter temperature deviates from that predicted from a linear progression of change with temperature of freezing.