Silver carp was treated by using single frequency ultrasound, dual-frequency ultrasound and tri-frequency ultrasound respectively, and the surface hydrophobicity and surface sulfydryl amount of silver carp myofibrillar protein were studied. The results indicated that surface hydrophobicity and surface sulfydryl amount increased firstly and then decreased as ultrasonic time extended. The surface hydrophobicity and surface sulfydryl amount increased to the maximum when the protein was treated with single frequency ultrasound and tri-frequency ultrasound respectively for 15 min and 10 min. The surface hydrophobicity of the protein treated with 80 kHz ultrasonic for 15 min and tri-frequency ultrasound increased by 56.88% and 65.34% individually compared to protein without ultrasound treatment, Meanwhile, surface sulfydryl amount increased by 11.19% and 13.32%, respectively. The effect of dual-frequency ultrasound on the surface hydrophobicity and surface sulfydryl amount was higher than the effect of single ultrasound but lower than that of the tri-frequency.
