Lactate Dehydrogenase Monoclonal Antibody Sandwich ELISA To Determine Cooking Temperature of Ground Beef

Monoclonal antibodies (MAb) to bovine muscle lactate dehydrogenase (LDH) were prepared and a sandwich enzyme-linked immunosorbent assay (ELISA) was developed, using MAb as capture antibodies and polyclonal antibodies as detector antibodies. The ability of the sandwich ELISA to quantify LDH was tested in a ground beef model system and commercial ground beef products cooked to different endpoint temperatures (EPT). The LDH content of extracts decreased from 805 μg/g of meat in ground beef cooked to 64 °C to 0.24 μg/g of meat cooked to 74 °C. Commercially cooked patties with EPTs between 68.3 and 71.1 °C averaged 3.38 μg of LDH/g of meat. Similar concentrations of LDH (about 3 μg/g of meat) were observed in both the model system and commercially cooked patties at EPT of about 70 °C. Fat content had no effect on the concentration of LDH in ground beef cooked to 69.4 °C. Five freeze−thaw cycles had no effect on the LDH concentration of raw ground beef. Repeated freezing and thawing of raw meat decreased the LDH concentration of cooked ground beef. LDH concentrations in most patties from six fast food restaurants suggested that all were cooked to at least the recommended EPT of 69.4 °C.