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Title: EVALUATION OF ANIMAL AGE AND MUSCLE TYPE ON BEEF LOG JUICE COLOUR AND RESIDUAL GOT ACTIVITY WHEN COOKED TO TARGET END-POINT TEMPERATURE OF 79.4 C

Author
item Senter, Samuel - Sam
item YOUNG, LOUIS
item LYON, BRENDA
item LYON, CLYDE

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The pink-juice test is a subjective method used by FSIS inspectors at ports-of-entry to test for end-point temperature (EPT) of 79.4 C (175 F) of cooked beef imported from countries where Foot and Mouth Disease is prevalent. These temperatures, required to inactivate the virus, must be rigidly enforced to prevent spreading of this disease to domestic herds. We have tested the pink-juice test procedures under controlled laboratory conditions using five cuts of beef from three age groups of animals to determine the validity of the test. This was done by measuring the color characteristics of the meat and juices both objectively and subjectively after cooking to the desired EPT, and by measuring residue from a specific enzyme glutamic- oxaloacetic transaminase (GOT) which we have shown previously to be indicative of EPTs. Red color remains in the meat juices at EPT 79.4 C, therefore, absence of red indicates that the meat has been subjected to adequate heat treatment. Cut of meat nor age of the animal had no significant effect on color and little effect on the residual GOT activity.

Technical Abstract: Effectiveness of the pink-juice test to determine 79.4 C end- point temperature (EPT) of cooked beef logs was appraised. Logs made from five cuts of meat from three animal age groups were fabricated in triplicate then cooked to EPTs of 78.0-81.8 C. CIELAB L*, a*, b*, C and h values of internal surfaces of freshly sliced meat and pressed juices from samples were determined. Residual glutamic-oxaloacetic transaminase (GOT) activity was determined as an indicator of EPT. Sensory ratings were made by six trained panelists to determine intensities of residual red color of the juices. Animal age and cut of meat had little effect on the CIELAB color values. Residual red color was apparent in all samples by both sensory and a* values analysis. Sensory ratings did not vary significantly (P < 0.05) by animal age or cut of meat. Average values of 3.2 (intensity range, 1-9) corresponded to an EPT slightly greater than 80 C. Residual GOT activity ranged from 482.5-1641.8 SFU ml of juice, differed significantly by cut of meat (P < 0.05), but not by animal age. It was concluded that if pink color is absent from the juice of cooked beef logs, EPT has exceed 79.4 C.