Effect of pulsed shock waves on the activity of polyphenol oxidase, alkaline phosphatase and green fluorescent protein

Pulsed shock waves (PSW), generated using a benchtop system constructed in our laboratory, have potential for the preservation of foods, pharmaceuticals and cosmetics, since they can inactivate micro-organisms as well as enzymes without heating. This paper presents the effect of PSW on polyphenol oxidase (PPO), which is related to food quality, and on alkaline phosphatase (AP), which is an indicator enzyme for milk pasteurisation. We also show the effect of PSW on green fluorescent protein (GFP). Results indicated that repeated applications of shock waves to enzymes and GFP at 4 °C were capable of reducing enzyme activity and the fluorescence of GFP. We showed that PSW decreased the activity of PPO and AP within a few microseconds at room temperature. The kinetics of enzyme activity reduction was affected by the number of applied shock wave pulses and followed an exponential relationship.