Control of Thermophilic Spore Activity with Pressurized COSub2 and Egg-WhiteLysozyme

摘要

The shelf life of low-acid (pH 5.4-5.6), thermally processed military rations,such as mixed vegetables or stews, can be limited by the metabolic activity of gram-positive, heat-resistant spore-formers, such as Bacillus stearothermophilus. For that reason, an investigation was initiated to evaluate the feasibility of using carbon dioxide (CO2) alone or in combination with egg white lysozyme to inactivate foodborne thermophilic sporeformers. Results showed that vegetative cells of B. stearothermophilus were very sensitive to hyperbaric (pressurized) CO2. During 3.5 h of incubation in AAMS broth at 25 deg C and 200 psi CO2, a 5-6 log10 cycle decrease occurred in the cell density. Similarly, at 400 psi CO2, a 6-7 log decrease occurred in the cell population. However, in the spore state, results indicated that B. stearothermophilus was more resistant to CO2 inhibition than vegetative cells.