The optimum thermosonication parameters, temperature and ultrasound energy density (UED), determined by using response surface methodology to inactivate polyphenol oxidase (PPO) and protecting the quality parameters, especially color of strawberry nectar. The PPO inactivation was successfully achieved by thermosonication treatment. Increasing of temperature resulted with decreasing of browning index and increasing of hydroxymethyl furfural. High temperature-low UED combination can be applied to obtain minimum change in Delta E* and maximum protection of ascorbic acid. Thermosonication at mild temperature (similar to 50 degrees C) and UED (similar to 230 J/g) ensured the maximum levels of total monomeric anthocyanin and total phenolic content. The combination of 59 degrees C and 455 J/g was the conditions of optimum thermosonication to minimize quality parameters which cause undesirable changes like color degradation in nectar and maximize desirable ones which have beneficial effects on characteristics of nectar or on human health like phenolic content of nectar.