LACTATE-DEHYDROGENASE ACTIVITY IN BOVINE MUSCLE AS A POTENTIAL HEATING END-POINT INDICATOR

Lactate dehydrogenase (LDH) activity was measured in heated extracts of cooked bovine muscle tissues to evaluate the potential for developing a rapid, accurate assay to verify cooking endpoint temperatures in beef. Adductor and semimembranosus muscles from six Angus steers were assigned to one of four treatments: fresh, frozen, frozen-thawed, or aged. Each treatment was applied to beef rounds that did or did not receive electrical stimulation. LDH activity rates were monitored in heated and unheated samples following 3 weeks of vacuum-packaged storage at 4-degrees-C. Treatments other than heating showed little effect on LDH activity. A major portion of activity was lost upon heating to 63-degrees-C, and only marginal activity was detectable at 66-degrees-C. Extractable protein decreased with increasing temperature. Decreases in LDH activity with increasing temperature may result from heat denaturation of the enzyme and/or from decreased amounts of extractable protein.