CONTROLLED-ATMOSPHERE STORAGE OF PORK UNDER CARBON-DIOXIDE

Fresh pork loin slices were packaged under three different anoxic atmo spheres (100% N-2, 100% CO2 and 50% N-2 + 50% CO2) and kept at two sto rage temperatures (-1 degrees C and 4 degrees C) and two pressures (1. 0 and 1.2 atm.) in reusable, gas impermeable metal boxes. A gas headsp ace to meat weight ratio of >3 1 per kg was maintained. Carbon dioxide concentrations were unchanged (controlled) during storage. Microbiolo gical, biochemical and physical measurements were made during the 3-we ek storage period. While atmospheric pressure did not have a significa nt impact on shelf-life, samples stored at -1 degrees C were satisfact ory at 21 days in both CO2 treatments. Samples under N-2 did not fare so well, showing higher levels of psychrotrophic bacteria after 18 day s at -1 degrees C and 14 days at 4 degrees C. Samples kept in N-2 at 4 degrees C were spoiled within 2 weeks. Bacterial growth was slowest u nder 100% CO2, but samples stored under 50%-50% N-2-CO2 at 4 degrees 0 C were also observed to be in good microbiological condition at 21 day s of storage. Use of CO2-containing atmospheres provided more than 7 e xtra days of shelf-life at 4 degrees C over that attainable under 100% N-2. Shelf-life at -1 degrees C was improved by 3 to 4 days over that at 4 degrees C. Except for the length of time in storage, treatments had only a minor effect on pH, color, water holding capacity and shear force. These physicochemical characteristics were not factors which l imited shelf-life.