Abstract:The effects of high pressure thermal sterilization (HPTS) combined with glucose on the sterilization effect and the impact on the inner membrane of Bacillus subtilis spores were investigated. The sterilization effect, ion release, intimal permeability, and membrane structure stability of Bacillus subtilis spores were studied through plate counting, conductivity measurement, flow cytometry analysis, and Fourier transform infrared spectroscopy analysis. The results showed that the inactivation rate of spores reached 4.64 lg with HPTS treatment of 600 MPa and 75 ℃, while the addition of 60% mass fraction glucose reduced the inactivation rate of spores by 2 lgs. As the mass concentration of glucose increased, the ion release of spores decreased significantly (P<0.05). The result of flow cytometry showed that the proportion of the positive region (M2) in the sample under 600 MPa and 75 ℃ with 60% mass fraction glucose treatment was 92.88%, indicating a significant increase in the intimal permeability of spores (P<0.05). By analysis of infrared spectroscopy in the 3 000~2 800 cm-1 band, it was found that compared to the HPTS treatment alone, HPTS combining with glucose resulted in a significant reduction in the absorption peak intensity of the characteristic functional group —CH2/—CH3 in the inner membrane of spores. Glucose contributed to the stability of inner membrane structure of spores. Therefore, the mass concentration of glucose has an important influence on the inactivation effects of HPTS on Bacillus subtilis spores.
