The Mechanism And Synergistic Measure Of Sterilizing Spores By High Pressure Carbon Dioxide

Spore is considered the strongest resistance in nature because of theirs special structure, and they bring many troubles in people's lives and production. High pressure carborn dioxide as a new sterilization technology, it not only can kill nutrition cells, but also spores in food. The mild temperature and the weak destory to sensitive materials, which is propitious to keep original characters. This thesis focused on technological conditions of sterilizing spores by supercritical carborn dioxide treatment, the effect of synergistic and bourgeoning reagents to kill spores, and the mechanism of sterilizing spores by supercritical carborn dioxide treatment. The main results were as follows:1) It was certain that the pressure, temperature and time were the main parameters by signal experiment. By orthogonal test the optimal decision to sterilize Bacillus subtilis spores was that pressure of 20MPa, temperature of 35℃,30mins and twice courses, and the log reduction of spores was 3.48.2) The ethanol and hydrogen peroxide have better synergistic reaction to kill spores. The log reduction can up to 4.85 by adding 0.6% hydrogen peroxide. But the function of isopropanol is rarely. L-alanine and glucose can also accelerate spores bourgeoning ordinary condition, but experimental group adding L-alanine has higher dead rate than adding glucose by supercritical carborn dioxide treeatment. The log reduction is 4.05 which adding 100mmol/L L-alanine.3) Compared with untreating samples, the spores treating by supercritical carborn dioxide, theirs shapes were changed partly observed by scan electron microscopy, and mechanical injure casued by pressure lead to dead. But the meantime formed bacteria hanging mission increased difficulty of sterilizing. For this reason, the degree of sterilizing is not thorough.4) Tested the leakage of protein and nucleic acid within spores, which leak by supercritical carborn dioxide treatment. But under the lower pressure and temperaure, the level of leakage was also less, and the ability of killing spores caused by mechanical force was feeble. So it was important to improve bourgeoning rate to sterilizing spores.