405 - Dark Storage of Enhanced Dark-cutting Beef in Nitrite-embedded Packaging Increased Metmyoglobin Formation upon Repackaging

The objective of this study was to evaluate nitrite-embedded packaging (NEP) and enhancement effects on the color of dark-cutting beef after repackaging into polyvinyl chloride (PVC) for display. From a commercial packing plant, dark-cutting beef strip loins (n = 8; pH = 6.39) and USDA Low Choice beef strip loins (normal-pH, n = 6) were collected. Bisected dark-cutting loins were randomly assigned to nonenhanced dark-cutting (DCN) and enhanced dark-cutting (DCE) with glucono delta-lactone and rosemary. Steaks (1.91 cm) sliced from nonenhanced normal-pH, DCN, and DCE loins were randomly assigned to 3, 6, or 9 d in dark storage, and DCE steaks were packaged in nitrite-embedded packaging (NEP) while normal-pH and DCN steaks packaged in vacuum packaging. At dark storage d of 3, 6, or 9, steaks were repackaged in PVC and displayed for 6 d. The instrumental color was evaluated every 12 h, and metmyoglobin formation was calculated using the ratio of reflectance of 572 nm and 525 nm. Delta E was calculated to determine the change in color over time using the change in L*, a*, and b* values from h 0 to h 12 of display. Data were analyzed using the Mixed Procedure of SAS, and least squares means were considered significant at P < 0.05 and separated using the PDIFF option. Metmyoglobin formation increased (P < 0.05) within 12 h of repackaging DCE steaks held for 3 d and 6 d of dark storage. At h 12 of display, DCE steaks had significantly more metmyoglobin formation than DCN and normal-pH steaks. The DE of DCE steaks was negative, indicating a decline in color after 12 h of display, while the normal-pH and DCN steaks had a positive DE value indicative of improved surface color. Therefore, repackaging DCE steaks resulted in decreased color stability and increased metmyoglobin formation.