Study Of High Pressure Treatment On The Inactivation Kinetics And Mechanism In Carrot POD And HRP

High pressure processing (HPP) technology is an emerging non-thermal food processing technology. Compared with the thermal processing, the qualuties of high pressurized food is closer to the natural quality with good flavor, high nutritional and more safety. Peroxidase can affect the products quality and is heat and pressure resistant, and is considered as the target enzyme in food processing.In the study, the inactavition conditions and isoenzyme changes of carrot peroxidase treated by HPP were studied using guaiacol method and PAGE electrophoresis, the effects of high pressure processing on conformation of horseradish peroxidase were studied using circular dichroism and fluorospectrophotometer. The study lay the foundation for using HPP to produce new carrot juice products. The results are as follows:1. High pressure treatment has obvious effect on the carrot POD inactivation. the residual activity of carrot POD decreased with the pressure increased, and the treatment of 200MPa for 15min had energized the activity, and the activity reached to 101.34%; the activity of carrot POD reach to the highest when the treatment temperature reach to 40℃and then the activity decreased rapidly with the temperature increased; pressure treatment for 15min had better inactivation of carrot POD; the quantity of isozymes changed with the pressure increased and the activity of carrot POD decreased.2. Kinetic parameters for inactivation of carrot POD by HPP treatment were obtained. Results showed that:at 20℃, the activity decreased rapidly with the increase in pressure, and it is sensitivity to pressure; At 20～50℃of constant temperature, higher temperature has resulted in a corresponding increase in the sensitivity of carrot POD activity; At 400MPa, activity decreased rapidly with the increase in temperature, and it is sensitivity to temperature; The prediction of the inactivation kinetic was certified to be well.3. The emission spectra characteristic peaks of pressurized horseradish peroxidase decreased the fluorescence intensity, the fluorescence intensity of samples treated by 100MPa,300MPa,500MPa were decreased by18.28%,5.46% and 4.04% in turn, and the differences are significant.(P<0.05)4. High pressure treatment changed the secondary structure of horseradish peroxidase. The content of a-helix in horseradish peroxidase pressurized by 100、300、500MPa increased 3.7%,3.5%,3.2%, and the content ofβ-sheet and random coils in horseradish peroxidase increased 4%,4.5%,4.5%and 3.7%,3.3%,3%, while the content ofβ-turn decreased 11.5%,11.4%,11.4%...