Frozen beef contamination after exposure to low levels of ammonia gas

Regulations and publications about food contaminated during ammonia refrigerant leaks provide limited information and recommendations, which means that contaminated products are often held for an indeterminate period or condemned. Moreover, the scientific literature offers little guidance on disposing of products exposed to low levels of ammonia refrigerant gas. We evaluated meat contaminated with low levels of ammonia under frozen storage conditions. Fresh beef semitendinosus muscles were trimmed of external fat; fabricated into 10 x 5 x 2.3 cm (height x width x depth) steaks; and exposed to 50, 100, 250, and 500 ppm ammonia gas (85 mL/min) in a plexiglass enclosure contained in a freezer for 6, 12, 24, and 48 h at -17 +/- 3 degrees C. Ammonia content in meat was analyzed by the indophenol method, and pH was measured according to AOAC official method 981.12. Ammonia levels and pH values increased significantly (P < 0.05) in the exposed meat with increasing exposure times and ammonia concentrations. Ammonia levels were 34.2, 51.5, 81.1, and 116 ppm, and pH values ranged from 5.56 to 5.75 (control range 5.31 to 5.43) when the meat was exposed to 50, 100, 250, 500 ppm for 48 h. Our results showed that meat ammonia content was low even with ammonia exposures as high as 500 ppm at freezing temperatures.