Carbon Dioxide as a Controller of the Spoilage Flora of Pork, with Special Reference to Temperature and Sodium Chloride

Abstract

The microflora of native pork and cured pork (3% NaCl) stored in air or CO₂ (89–100%) at 0°C and 4°C were studied. The flora on native pork was followed both on fat and on lean surfaces. At 0°C the time taken for the lean pork to reach 10⁶ cfu/cm² was 6 times longer in CO₂ than in air (4 times at 4°C). The corresponding factor for cured pork was 10 at 0°C. The microflora was identified at the point of spoilage or just before. On lean and fat pork stored in air Pseudomonas spp. dominated. On fat significant amounts of Alteromonas spp. and Brochothrix thermosphacta were also found. The cured pork stored in air was dominated by B. thermosphacta while Pseudomonas constituted 20% of the flora. In CO₂ Lactobacillus spp. dominated to 100%, except on fat where Alteromonas spp. were also found. The combination of CO₂ and storage at 0°C suppressed growth of B. thermosphacta, Enterobacteriaceae, yeasts and molds. The study points to two practical implications: (a) storage in 100% CO₂ at 0°C gives the meat a shelf-life of about 3 months, (b) a combination of curing and storage in 100% CO₂ at 0°C gives the meat a shelf-life of more than 5 months.