Nonthermal Pasteurization of Lactic acid bacteria by High Intensity Light Pulse

광 펄스에 의한 젖산균의 비열 살균

  • Cho, Hyung-Yong (Department of Food Science & Technology, Chonju Kijeon Women's College) ;
  • Shin, Jung-Kue (Cheiljedang Co., R&D Center of Foods) ;
  • Song, Young-Ae (Department of Agriculture Chemistry, WonKwang University) ;
  • Yoon, Seon-Joo (Department of Biomaterials Science and Engineering, Yonsei University) ;
  • Kim, Joong-Man (Department of Agriculture Chemistry, WonKwang University) ;
  • Pyun, Yu-Ryang (Department of Biotechnology, Yonsei University)
  • Published : 2002.08.01

Abstract

Lethality of high intensity light pulse on the pre-determined microbial populations has been investigated. Prior to the treatment, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Pediococcus pentosaceus were cultivated separately onto the surface of Lactobacilli MRS agar. Pre-determined microbial populations were applied to the test media and these sample were exposed to high intense light source with an exposure time ranging from 1 to $2500\;{\mu}s$. Results showed that at least 200 light pulses of $1\;{\mu}s$ duration were required to reduce L. Plantarum cells by 90% at 25 kV, the greater the number of light pulses, the larger the reduction in viable cell numbers. Viable cells of L. plantarum and the others were reduced by more than 5 and 6 log cycles at the upper exposure level of $750\;{\mu}s$, respectively. These study shows that pulsed light emissions can significantly reduce populations of lactic acid bacteria on exposed surface with exposure times. Killing efficiency for L. plantarum significantly increased with decreasing the distance between the lamp and the surface of samples.

Lactobacillus plantarum, Lactbacillus brevis, Leuconostoc mesenteroids, Pediococcus pentosaceus를 대상으로 하여 광펄스 처리에 따른 미생물의 영향에 대하여 검토하였다. 광원에 인가하는 전압의 세기를 15-25 kV로 하고 $2500\;{\mu}s$ 이내의 처리시간으로 젖산균 세포를 광 펄스 처리하였을 경우 빛의 세기가 증가할수록 사멸 속도와 사멸율이 증가하였으며, $1500\;{\mu}s$ 처리후에는 빛의 세기에 상관없이 7 log 정도의 동일한 사멸율을 나타내었다. 빛의 세기 25 kV에서 광원과 시료 표면의 거리를 60, 85, 110, 135 mm으로 변화를 주어 처리한 결과 광원과 시료 표면과의 거리가 가까울수록 높은 살균율을 나타내었다. 광펄스 처리시 시료 표면의 온도 상승은 $5^{\circ}C$ 미만으로 거의 나타나지 않았다. 광펄스 처리후 투과 전자 현미경으로 형태적인 변화를 관찰한 결과 광펄스 처리를 한 세포는 처리하지 않은 세포에 비해 세포내 물질이 상당 부분 손실되었으며, 일부 세포막과 세포벽에 손상이 일어났음을 알 수 있었다.

Keywords

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