Acid phosphatase activity and color changes in consumer-style griddle-cooked ground beef patties

Abstract

The U.S. Department of Agriculture and the Food and Drug Administration have issued temperature requirements to help consumers cook beef patty products that are free of pathogens. Verification of end-point temperature (EFT) is needed in cooked meat products due to concerns over outbreaks of Escherichia coli 0157:H7. Acid phosphatase (ACP) activity was studied as a potential method for determination of EFT in ground beef patties cooked nonfrozen, patties frozen 7 days and thawed at room temperature 4 h 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 EPTs. Expressed meat juice and internal meat patty color decreased in redness as EFT 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. Logl0 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.