Abstract: During processing fruit and vegetable, the combined treatment of high-pressure jet and medium temperature cancontribute intrinsic colour, flavor and good quality to processed food, which will thus be extremely helpful in the field of foodproduction. Based on the impulsed pressurization brought by continuously high-pressure jet, the effects of the processing onthe peroxidase (POD) activity in wax gourd juices are discussed in this paper. Results show that the processing conditions suchas pressure, temperature, ambient pH value and treatment time can influence greatly the POD activity. POD can be inactivatedunder the pressure of >50MPa or the material temperature of 35℃ and 55℃, while this enzyme can be activated under <40MPa or the material temperature of 45℃. When the temperature of raw material is 35℃, the pressure is 20MPa and the treatmenttime is 4min, the acidity of pH 2.99 can inactivate subtotal POD, while the effect of pH 4.96 and 5.96 is contrary. In addition,POD is activated in the beginning, and then is inactivated gradually along with lasting of the treatment time. And the higher thepressure is treated, the shorter the processing time used to inactivate POD.

Key words: high-pressure jet, medium temperature, combined treatment, POD, activity