Effects of ultrasonic treatment on physico-chemical properties and structure of tuna (Thunnus tonggol) myofibrillar proteins

•The physico-chemical properties of MPs were affected by ultrasonication.•The particle size distribution became more uniform after ultrasonic treatment.•The hydrophobic group was exposed to the surface of protein after ultrasonic treatment.•The values of the rheological parameters' were higher than that of control group. The effects of different ultrasonication times (0 min, 6 min, 12 min, 18 min, and 24 min) at 280 W and of ultrasonic powers (0 W, 160 W, 280 W, and 400 W) for 12 min on the physico-chemical properties, electrophoresis pattern, particle size distribution, thermal stability, and rheological behavior of tuna myofibrillar proteins (MPs) were investigated. The results indicated that protein solubility and active sulfhydryl content changed little with the increase in ultrasonic power, while myofibrillar protein content decreased with the increase of ultrasonication time. The surface hydrophobicity of myofibrin increased with the increase in ultrasonication power and time. The results of ultraviolet spectrum analysis showed that the hydrophobic group was exposed to the surface of protein after ultrasonic treatment, and the particle size distribution became more uniform after ultrasonic treatment. The dynamic rheology results indicated that the storage modulus G′ and the loss modulus G′′ are increased.