Study on Microbial Control of Food Using Carbon Dioxide

Carbon dioxide (CO2) is a safe and inexpensive gas that is used as a food additive. In this study, microbial control by pressurized CO2 was examined. Pre-solubilization of CO2 at 1 MPa at 4 degrees C markedly decreased the heat tolerance of vegetative bacterial cells through acidification of intracellular pH. Further, a 5- to 6-log reduction in vegetative bacterial cells was observed after incubation at around 60 degrees C for 1 min. The inactivation effect of pressurized CO2 on bacterial spores was increased in the presence of monoglycerol monocaprate (MC10; 0.05 % w/v). The pressurized CO2 accelerated MC10 adhesion to the spores as well as the release of dipicolinic acid from the spores, considerably decreasing physiological germination and/or heat resistance. When pressurized CO2 was applied during the fermentation of sardine fish sauce, the salt concentration required for the inhibition of undesirable microorganism growth was reduced from 20 % to 10 %. In addition, the reduction of salt in fish sauce improved its nutritional and sensory qualities compared to that produced by the conventional method. These findings support the practical application of CO2 for microbial control in foods and contribute to the development of improved food processing methods.