科研之友
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摘要
Pulsed electric field (PEF) is a promising nonthermal food preservation technology that is based on the use of electric field to eradicate spoilage and pathogenic microorganisms in food products. The effect of various biological factors on the transmembrane potential of different microorganisms (Staphyloccocus aureus, Escherichia coli DH5 alpha, and Saccharomyces cerevisiae) was investigated by means of both numerical simulation and experimental method. The PEF resistance of different microorganisms in grape juice was compared by applying field strength of 12-24 kV/cm, treatment time of 30-180 mu s, and an initial temperature of 30 A(0)C. The results showed that S. cerevisiae exhibited the least resistance to PEF treatment, E. coli DH5 alpha the second, and S. aureus the third. The simulation results indicated that larger cells like S. cerevisiae presented the higher values of transmembrane potential and induced field strength around the cells compared to E. coli DH5 alpha and S. aureus, which led to a less resistance to PEF treatment. The effect of cell orientation on the induced transmembrane potential was very slight (1.67 % for E. coli DH5 alpha and 3.43 % for S. cerevisiae). The thicker cell membrane caused concentrated electric field in the cell membrane, which enhanced the sensitivity of microorganism to PEF treatment. However, both transmembrane potential and electric field strength decreased with the thickness of cell wall increasing. According to both experimental and simulation results, it was evident that there was significant difference in the inactivation rate between different microorganisms, which could be largely attributed to the biological factors of different microorganisms.
- 出版日期2014-7
- 单位浙江大学
