Internal Premature Browning in Cooked Ground Beef Patties from High-Oxygen Modified-Atmosphere Packaging

ABSTRACT: This study examined the effects of location within a package and display time on the incidence of premature browning in patties made from ground beef packaged in a high-oxygen modified atmosphere (80% oxygen and 20% carbon dioxide) or in vacuum for up to 14 d. On days 3, 5, 8, 10, 12, and 14 of display, patties were formed from both top and bottom portions of tissue exposed to high-oxygen. These patties contained predominantly oxymyoglobin and metmyoglobin at the time of formation and cooking. As display progressed, the percentage of oxymyoglobin decreased ( P < 0.05) and metmyoglobin increased ( P < 0.05) in the patties for both locations, whereas the percentage of deoxymyoglobin remained stable at less than 2%. Samples that were vacuum-packaged contained predominantly deoxymyoglobin. Patties from high-oxygen packages cooked to a temperature of 71.1 °C were prematurely brown ( P < 0.05) compared with vacuum-packaged samples. Patties containing predominantly deoxymyoglobin remained pinker than patties cooked directly from high-oxygen packages (lower visual color score, higher a * value; P < 0.05) on the interior after cooking. Data in this study clearly demonstrate that, regardless of time in display, nearly 100% of patties formed from high-oxygen-packaged ground beef would be prematurely brown when cooked and could pose a food safety problem if not cooked to an endpoint temperature ensuring safety.