Abstract: In the food industry, eliminating harmful microorganisms and inactivating enzymes are important for food quality and also for public health. That is the reason why heat treatment is the most utilized method for stabilizing foods because of its capacity to destroy microorganisms and also to inactivate enzymes. However, since, heat can alter the organoleptic properties of foods and diminish the contents or bioavailability of some nutrients, there is a growing interest in searching non-thermal method for food preservation. Ultrasonication combined sanitizers can accelerate the rate of sterilization and enzymatic inactivation. The advantages of ultrasound over heat treatment include: minimization of flavor loss and significant energy saving. In our research, we approach to a new way by using ultrasonic combined with perasan to inhibitate polyphenol oxidase activity. Microbial sanitation is also a benefit from this process. Main purposes of this research are to prevent black spot (melanosis) and sanitize microorganism on shrimp without effecting to texture (firmness) and apprearance (L) of finished product. Our results show that optimal parameters of ultrasonic combined PAA are as follows: amplitude (120 μ), chemical concentration (40 ppm), temperature (12°C) and time (9 min).