Enzymatic Reduction of Metmyoglobin by Ground Beef

Abstract

SUMMARY A method is described for estimating the ability of ground meat to reduce metmyoglobin enzymatically. The method involves a complete oxidation of all pigments to metmyoglobin by the addition of ferricyanide, followed by measurement of metmyoglobin reduction by the meat in 1 hr. The work was confined to beef rib eye muscle. Metmyoglobin‐reducing activity (MRA) showed great fluctuations in rib eyes from different animals. It was correlated with total pigment. In any one sample of meat, MRA increased with pH from pH 5.1 to 7.1 and with temperature from 3°C to 35°C. It declined only slightly in whole cuts of meat stored for several days in the refrigerator, but much more rapidly in stored ground meat. Chlortetracycline did not interfere with MRA, but 5% salt completely inhibited it. A possible reductive mechanism is discussed briefly.