Study On Extraction Mechanism Of Sterilization In Supercritical Carbon Dioxide

Supercritical carbon dioxide is a non-thermal method which has received considerable attention for potential applications in a number of processing fields. There is a lot of the advantages than any old sterilizations such as low temperature,non-residual,nocontamination and nutritional.This article discusses the killing effect of supercritical carbon dioxide to E. coli under the conditions of different pressure, temperature, processing time, medium and the cell concentration,pH value of suspension.In addition,conduct an orthogonal experiment on the four factors of the three main levels, Given full consideration to the impact of the interaction of experiment.single-factor Experiments show that when pressure of 20MPa, temperature of 40℃, the processing time for 30min and bacteria suspension pH to 5, the sterilization is best If all factors be considered in isolation.The Orthogonal experiment shows that the pressure and temperature are two significant factors that affect the experimental results,the interaction of pressure and other factors is not significant.The experimental results show that The new technology to kill E. coli is more pronounced effective and in line with national standards in sterilization.Supercritical carbon dioxide is a good solvent. Supercritical carbon dioxide can extract function substances from microbial cells, cell membrane function and cell wall by which the microbial cells was damaged, so that the microorganisms die of the loss of activity. In this study, through the process of E. coli cell suspension by supercritical fluid we have found out the best conditions of sterilization process, and the changes in cell morphology of E. coli before and after the supercritical fluid processing. Analyzed the components of different time quantum extractive, traced back to their sources in E. coli microbial cell, investigated the extraction mechanism in supercritical carbon dioxide extraction process. Through analyzed the component of the time quantum extractive, it can be found out that the extractive mainly divided into two types of components:one is small molecule amino acid with low polarity,another is aliphatic acid. To visualize the changes occurring in the superciitic carbon dioxide treated and untread, the changes were unobvious. Through the analysis of supercritical fluid extraction treatment components, and traced the source of these components, which can be confirmed to contained in E. coli cells. It proved that the extraction did occured in the process of supercritical sterilization.