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KMID : 1007519990080040261
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Food Science and Biotechnology
1999 Volume.8 No. 4 p.261 ~ p.266
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Cell Damage and Recovery Characteristics of Lactobacillus plantarum by High Voltage Pulsed Electric Fields Treatment
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Pyun Yu-Ryang
Shin Hae-Hun
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Abstract
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The effect of high voltage pulsed electric fields (PEF) on the viability of Lactobacillus plantarum ATCC 14917 was investigated under controlled temperatures by using a circulating treatment chamber. The rate of inactivation increased with an increase in treatment temperature, and the extent of injury of cells increased as temperature and treatment time increased. The observed difference in survivability of the PEF treated cells on lactobacilli MRS and MRSS (MRS + 4% NaCl) media indicated that the lethal effect of treatment temperature on cells must be much more sensitive than the results assessed by usual plate count, and a considerably higher number of cells was actually injured but did not lose colony-forming ability, particularly at a relatively high treatment temperature and short treatment time. The cells treated with an electric field strength of 45 kV/㎝ at 50℃ for 500 ㎲ retained the general rod shapes, but indentations were observed on the cell surface by scanning electron microscopy. The cell wall was broken, and cytoplasmic materials leaking out of the cells were observed by transmission electron microscopy. The regrowth of PEF-treated cells was delayed by double the time of untreated cells and the final acidity of the culture broth was about 50% of untreated cells after 45 h cultivation.
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