Effect Of Ultra High Pressure Treatment On Vibrio Parahaemolyticus And Its Application In Surimi Products

This study explored the mechanism of the microbial inactivation by high hydrostatic pressure, and investigated the damages inflicted on the Vibrio Parahaemolyticus cells treated by ultra high pressure. The work provided theoretic evidence by building the mechanical model of membrane under the pressure. Then the effect of ultra high pressure processing on fish balls as well as the shelf life of treated fish were investigated. The results were as followed.The effect of ultra high pressure treatment on the lethal rate, the ultra-structure, membrane permeability, ATPase activity of Vibio Parahaemolyticus were studied. Viable cell counts were not detected following pressure treatment at 300MPa. High pressure treatment caused changes in the microstructure of the cell, the membrane proteins of cells were damaged, and the cell membrane permeability increased, resulting in leakage of the cell. The membrane ATPase activity also decreased under high pressure treatment. This study showed that the damage of cell membrane was the main reason for microorganisms inactivated by ultra high pressure.In this study the mechanical model of membrane under the pressure was set up. In the model, we suppose some modulus and simplify the structure. The analysis of the model gave us some interprets for the biological phenomena on cell membrane damaged under pressure.Effect of ultra high pressure treatment on fish balls were studied, the single-factor experiments and a group of orthogonal experiments were carried out. The results showed that the different sterilization effect of three factors on the fish balls was:pressure>synergetic temperature> dwell time. The best optimal parameter of sterilization technology was that:400MPa of pressure,30℃of synergetic temperature,5 min of dwell time.The shelf life of the high pressure treated fish balls was investigated. The treated samples could achieve a 49-day shelf life at 0℃. The whiteness and springiness did not change significantly during chilled storage, the hardness and pH increased after 30 days storage. TVB-N and TBA values also did not change significantly during storage. So the ultra high pressure processing could improve the quality of surimi products while extending its shelf life.