Abstract: This study investigated the effects of ultrasound treatment at different powers (0, 150, 300, 450 and 600 W) and a 20 kHz frequency for different durations (0, 5, 10 and 15 minutes) on the structure, physicochemical properties and emulsifying performance of sarcoplasmic proteins (SP) extracted from pale, soft and exudative (PSE)-like chicken meat. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed no significant changes in the composition of SP before and after ultrasound treatment. Circular dichroism (CD) spectroscopy showed that sonication did not alter the secondary structure of PSE-like chicken SP. Both ultrasonic treatment time and power had significant effects on the particle size, turbidity, potential, surface hydrophobicity, fluorescence intensity, ultraviolet (UV) absorption spectrum, solubility, and emulsifying properties of SP. With increasing ultrasonication time and ultrasonic power, the average particle size and turbidity of SP decreased significantly (P < 0.05), reaching minimum values of 237.2 nm and 0.018, respectively. The absolute value of zeta potential, solubility, surface hydrophobicity, and fluorescence intensity significantly increased. Experimental results showed that the most pronounced effects were observed at a 600 W power and 15 min, resulting in an up to 44.72% increase in solubility compared with the control group. In addition, ultrasonication could significantly increase the emulsifying activity index (EAI) and emulsion stability index (ESI) of SP, and reduced the turbiscan stability index (TSI) of the emulsion stabilized by SP (P < 0.05). The highest emulsifying performance of SP was observed after ultrasonication at 20 kHz, 300 W for 15 min, with a 79.18% increase in EAI and a 44.87% increase in ESI. In summary, ultrasonication changed the structural properties of PSE-like chicken SP and effectively improved its solubility and emulsifying properties.

Key words: pale, soft and exudative-like chicken, sarcoplasmic protein, ultrasonic treatment, structure, emulsifying properties