LACTATE-DEHYDROGENASE MONOCLONAL-ANTIBODY SANDWICH ELISA TO DETERMINECOOKING TEMPERATURE OF GROUND-BEEF

Monoclonal antibodies (MAb) to bovine muscle lactate dehydrogenase (LD H) were prepared and a sandwich enzyme-linked immunosorbent assay (ELI SA) was developed, using MAb as capture antibodies and polyclonal anti bodies as detector antibodies. The ability of the sandwich ELISA to qu antify LDH was tested in a ground beef model system and commercial gro und beef products cooked to different endpoint temperatures (EPT). The LDH content of extracts decreased from 805 mu g/g of meat in ground b eef cooked to 64 degrees C to 0.24 mu g/g of meat cooked to 74 degrees C. Commercially cooked patties with EPTs between 68.3 and 71.1 degree s C averaged 3.38 mu g of LDH/g of meat. Similar concentrations of LDH (about 3 mu g/g of meat) were observed in both the model system and c ommercially cooked patties at EPT of about 70 degrees C. Fat content h ad no effect on the concentration of LDH in ground beef cooked to 69.4 degrees C. Five freeze-thaw cycles had no effect on the LDH concentra tion of raw ground beef. Repeated freezing and thawing of raw meat dec reased the LDH concentration of cooked ground beef. LDH concentrations in mast patties from six fast food restaurants suggested that all wer e cooked to at least the recommended EPT of 69.4 degrees C.