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Title: ACID PHOSPHATASE ACTIVITY AND COLOR CHANGES IN CONSUMER STYLE GRIDDLE COOKED GROUND BEEF PATTIES

Author
item LYON, BRENDA
item DAVIS, C - RETIRED ARS
item WINDHAM, WILLIAM
item LYON, CLYDE

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2001
Publication Date: 8/1/2001
Citation: LYON, B.G., DAVIS, C.E., WINDHAM, W.R., LYON, C.E. ACID PHOSPHATASE ACTIVITY AND COLOR CHANGES IN CONSUMER STYLE GRIDDLE COOKED GROUND BEEF PATTIES. JOURNAL OF FOOD PROTECTION. 2001. VOL. 64, ISS. 8. PP. 1199-1205.

Interpretive Summary: USDA and FDA have issued temperature requirements to help consumers cook beef patty products that are free of pathogens. Verification of end-point temperature (EPT) is needed in cooked meat products due to concerns over outbreaks of E. coli 0157:H7. Acid phosphatase (ACP) activity was studied as a potential method for determination of EPT in ground beef patties cooked non-frozen, patties frozen 7 days and thawed at room temperature 4 in a refrigerator or by microwave, and patties made from ground beef frozen in store packages, then thawed in a refrigerator overnight. Pressed-out meat juices were analyzed from patties (n=314) cooked to 57.2 C (135 F), 65.6 C (150 F), 71.1 C (160 F), and 79.4 C (175 F) target EPT's. Expressed meat juice and internal meat patty color decreased in redness as EPT increased. Freezing whole packs with slow refrigerator or room temperature thawing caused significantly greater loss of redness in expressed cooked meat juice than did other handling methods. Log10 ACP had a significant linear (R2=0.99) response to EPT. Results show that the 3 to 5 min ACP test could be used to verify EPT in griddle-cooked hamburger patties. Key Words: Cooking temperature, enzyme activity, hamburger, meat juice, color

Technical Abstract: Cooking hamburgers to an internal temperature of 160 F (71.1 C) or higher destroys the harmful bacteria E. Coli O157:H7, which could be present in the raw meat. However, research has shown that visual color is not a reliable indicator of degree of cooking, and a thermometer to measure internal temperature is recommended. A rapid, easy test is needed to verify after-the-fact internal end-point temperature of ground beef patties. In this study, color and acid phosphatase (ACP), an enzyme, were evaluated as indicators of end-point temperature of beef patties prepared according to home-style practices. Expressed meat juice and internal meat patty color decreased in redness as temperature increased, but varied according to handling treatment and temperature. Log 10 ACP had a significant linear R2=0.99) response to end-point temperature. These results show that the 3 to 5 min ACP test could be used to verify end-point ttemperature in griddle-cooked hamburger patties.