Lactate Dehydrogenase Activity as an Endpoint Heating Indicator in Cooked Beef

Abstract

Lactate dehydrogenase (LDH, E.C. 1.1.1.27) activity, specifically LDH5 isoenzyme, declined significantly when bovine Semimembranosus (SM) slurries were heated from 57Њ to 66ЊC. When SM whole muscle roasts were brine pumped and oven-cooked, total LDH and specific activities declined proportionately from 57Њ to 63ЊC resulting in almost no activity at 63Њ ‫ע‬ 0.5ЊC. LDH activities were consistently higher in younger cattle and lower in older cattle for SM, Infraspinatus (IN) and Longissimus dorsi (LD) muscles and were lowest overall in the IN. LDH colorimetric and fluorescent assays were more accurate indicators for predicting beef roast heating temperature endpoints between 60Њ and 63ЊC than the USDA-FSIS method.

Coagulation test for determining end-point temperature of heated blue marlin meat

“…After native PAGE was achieved, LDH band was visualized by incubating the gel in LDH activity staining solution as described by Markert and Faulhaber. 20 Lactate dehydrogenase activity was assayed spectrophotometrically 21 with continuous monitoring of the decrease in absorbance at 340 nm due to oxidation of NADH using a UV-visible recording spectrophotometer (UV-160; Shimadzu Corp.). Activity of LDH in international units was calculated according to Stalder et al 21 GADPH activity was determined by the method of Krebs.…”

“…20 Lactate dehydrogenase activity was assayed spectrophotometrically 21 with continuous monitoring of the decrease in absorbance at 340 nm due to oxidation of NADH using a UV-visible recording spectrophotometer (UV-160; Shimadzu Corp.). Activity of LDH in international units was calculated according to Stalder et al 21 GADPH activity was determined by the method of Krebs. 22 In order to determine the thermal stability of LDH, the LDH fractions obtained by Sephadex G-100 gel filtration chromatography were dialyzed against 0.1 M phosphate buffer (pH 6.0) containing 0.9% NaCl and kept in the same buffer at various temperatures (60-70°C) for 5 min.…”

Double enzyme‐catalyzed microreactors using capillary electrophoresis

“…The percentage of phosphate (ATP:ADP:AMP) found at the completion of the experiment is 29, 40, and 31%, respectively. This can be compared to 25, 30, and 45% found in the previous experiment. Reasons for this difference in AMP formed is the same as that stated earlier.…”