Influence of Subzero Isochoric Treatment on Qualityof Ground Beef during Refrigerated Storage

Microbial contamination and oxidative processes limit the shelf life of fresh ground beef. In this study, subzero isochoric cooling was used to extend the shelf life of ground beef. The meat samples were packed with negligible headspace, treated at −9 °C/72 MPa for 1 or 3 days, and stored in the refrigerator at 5 °C for 14 days. Nontreated refrigerated samples were used as controls. In addition, the effects of adding mixed tocopherols were evaluated. Control samples rapidly browned during refrigeration, accumulated metmyoglobin, and showed increased microbial load and lipid oxidation. In comparison, subzero isochoric cooling for 1 day and 3 days retained microbial load below 5 Log CFU/g for 6 and 10 days, respectively. Also, isochoric-treated samples maintained the most redness and the least discoloration throughout the refrigeration period due to the low metmyoglobin concentration. The addition of tocopherols to ground beef samples led to increased lipid oxidation during refrigeration. In contrast, when ground beef samples were subjected to isochoric treatment, the addition of tocopherols did not result in lipid oxidation. This study shows that subzero isochoric cooling significantly enhances the shelf life and color stability of fresh ground beef by reducing microbial growth, limiting metmyoglobin formation, and mitigating lipid oxidation during refrigerated storage.