Low O2 master bag for beef patties: effects of primary package permeability and structure

The contribution of the structure and permeability of case-ready units on the colour changes of ground beef patties during low O2 storage in master bags, aerobic blooming and display life was investigated. We selected the following case-ready solutions: PVC 8000-+-closed-cell expanded polystyrene (EPS) tray, PVC 20000-+-closed-cell EPS tray, linear low-density polyethylene (LLDPE) 26000-+-closed-cell EPS tray and PVC 20000-+-open-cell EPS tray. Patties packaged onto a closed-cell tray and wrapped with PVC 20000, but never stored in master bag, were taken as a control. We monitored oxygen depletion in the headspace of the master bags, the microbiological indexes and the appearance of the patties (colorimetric measurements and scanning images). During the storage in master bags, the use of a very high permeability wrapping film and an open-cell EPS tray allowed the best colour stability of the bottom and upper sides of patties through 7-days. After master bag opening, the same combination of materials favoured the blooming of the upper surface pigments of the product and the stability of the oxygenated pigments during the display life. Moreover, the open-cell trays helped in reducing the discolouration of the bottom side of patties. Hence, this low O2 master bag system can enhance the colour stability of ground beef patties and therefore extend their distribution life.