EFFECT OF THERMAL-PROCESSING AND ADDITIVES ON THE KINETICS OF OXYTETRACYCLINE DEGRADATION IN PORK MUSCLE

The degradation of oxytetracycline (OTC) was observed at 60, 70, and 8 0 degrees C in several different aqueous and tissue media. In aqueous media, the rate of OTC degradation (k(obs)) was found to be independen t of glycerol adjusted water activities in the range of 0.6 to 1.0. Or thophosphate was observed to increase k(obs); in contrast, polymeric p hosphates (sodium pyrophosphate, sodium tripolyphosphate, and sodium h exametaphosphate) were observed to significantly decrease k(obs). Sodi um nitrite decreased k(obs) at 80 degrees C. OTC degradation was found to occur at a slower rate in porcine tissue than in aqueous media. Ad dition of orthophospate (0.5% as anhydrous dibasic sodium phosphate) t o tissue resulted in no observable change in k(obs); addition of polyp hosphates (equivalent to 0.5% anhydrous dibasic sodium phosphate) incr eased k(obs) Sodium nitrite (200 ppm) in tissue increased k(obs) at 60 degrees C but decreased it at 80 degrees C. Inclusion of calcium chlo ride significantly decreased k(obs) in both aqueous and tissue matrice s. Thermal treatments-food additive combinations were found to have si gnificant effects upon the rate of OTC degradation.