Effects of sodium nitrite and tocopherol incorporated poly (lactic acid) films on dark-cutting beef

Abstract

This study aimed to determine the effects of poly(lactic acid)-(PLA) films incorporating sodium nitrite and α-tocopherol on dark-cutting beef. A low-concentration (LC) PLA pellet was compounded with 0.12% sodium nitrite and 0.5% α-tocopherol. In addition, a high-concentration (HC) PLA pellet incorporated 0.6% sodium nitrite and 2.5% α-tocopherol. Extruded PLA pellets were oven dried before use. Pellets were compressed and molded using a hot press to form film sheets for packaging application. Steaks from seven dark-cutting loins (n = 7) were randomly assigned to either a polyvinyl chloride (PVC) overwrap, or a control, LC-PLA, or HC-PLA vacuum package. Normal-pH loins (n = 7) were sliced, and steaks were randomly chosen for PVC overwrap. Steaks were placed in simulated retail display for 6 d. Surface color was evaluated every 24 h with instrumental analysis and a trained color panel (n = 6). On d 5 of the display, half of the steaks were removed from the display and cooked to 71°C on a George Foreman grill to evaluate the cooked color. The remaining steaks on d 6 were used to evaluate microbial growth and lipid oxidation. The data were analyzed using the GLIMMIX procedure of SAS and considered significant at P < 0.05. There was a significant increase in redness for steaks in both LC-PLA and HC-PLA within the first 24 h of display. Additionally, HC-PLA steaks showed increased (P < 0.05) redness throughout the entire duration of display than all other dark-cutting steak treatments. Moreover, LC-PLA steaks showed greater redness (P < 0.05) than dark-cutting steaks in vacuum packaging during display. Once cooked, steaks packaged with HC-PLA showed greater (P < 0.05) external cooked color redness than all other treatments. In addition, HC-PLA steaks presented greater (P < 0.05) internal cooked color redness than dark-cutting steaks in vacuum and PVC overwrap and normal-pH in PVC. However, LC-PLA steaks demonstrated similar (P > 0.05) external and internal cooked color redness to dark-cutting steaks in vacuum packaging. In conclusion, the application of LC-PLA improved the retail display color without significantly impacting the cooked color of dark-cutting beef.