Studies Of The Effects On The Microbial Life Structure & Activity By Dynamic Actions

Dynamic pasteurization is a developing non-thermal process for food preservation. This paper was concerned about the effects on the microbial life structure and activity by the dynamic actions, such as the strong cut, high-speed impaction, sharp friction, and sudden pressure drop, etc. Saccharomyces cerevisiae and Bacilus subtilis suspensions were used.Observed from optical microscope and Transmission Electron Microscope, microbial body was part-penetrated, broken, ruptured, even fragmented. The results of observation showed that impaction, shake, friction and cut were the obvious dynamic actions, resulted in break, penetration, peel-off and worn-out, respectively. The results showed that the yeasts were dead in single pass when the homogenization pressure is over 120Mpa. The number of (Bacillus subtilis was dropped by 105 to 107 times by the dynamic actions, but no marked effects on the life activity of (Bacillus subtilis' spores were found. It can be concluded from the observation results that the breakage to bacterial cells included two ways: dominant breakage and recessive breakage. Both of them influenced the life activity of bacterial cells.The feasibility of dynamic pasteurization was studied based on the raw milk. After processed, the number of coliform colony reduced to below 10 cfu/ml; the total plate counts reduced to 3-log, which was close to the effects of pasteurization.