Controlled-Atmosphere Storage of Pork Under Carbon Dioxide

Abstract

Fresh pork loin slices were packaged under three different anoxic atmospheres (100% N2, 100% CO2 and 50% N2 + 50% CO2) and kept at two storage temperatures (−1°C and 4°C) and two pressures (1.0 and 1.2 atm.) in reusable, gas impermeable metal boxes. A gas headspace to meat weight ratio of >31 per kg was maintained. Carbon dioxide concentrations were unchanged (controlled) during storage. Microbiological, biochemical and physical measurements were made during the 3-week storage period.While atmospheric pressure did not have a significant impact on shelf-life, samples stored at −1°C were satisfactory at 21 days in both CO2 treatments. Samples under N2 did not fare so well, showing higher levels of psychrotrophic bacteria after 18 days at −1°C and 14 days at 4°C. Samples kept in N2 at 4°C were spoiled within 2 weeks. Bacterial growth was slowest under 100% CO2, but samples stored under 50%–50% N2–CO2 at 4°C were also observed to be in good microbiological condition at 21 days of storage. Use of CO2-containing atmospheres provided more than 7 extra days of shelf-life at 4°C over that attainable under 100% N2. Shelf-life at −1°C was improved by 3 to 4 days over that at 4°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 limited shelf-life.