Investigating the effects of ultrasound and alkaline pH on protein recovery from Acipenser baerii heads: Insight into ultrastructural, functional and antioxidant attributes

This study investigated the effects of ultrasound combination and alkaline pH adjustment on protein extraction from Siberian sturgeon (Acipenser baerii). Optimal protein extraction, solubility, and essential amino acid content were achieved at pH 11.5, within the tested range of 10.5 to 12.5. Ultrasound, applied at power levels ranging from 100 to 400 W, enhanced protein yield and functional properties, including foaming, which peaked at 65.35 % at pH 11.5, and emulsification, which increased to 82.50 % when combined with 400 W ultrasound at the same pH. Additionally, gelation properties and water-holding capacity were improved. The treated proteins also exhibited significantly enhanced sensory quality compared to the control group. Increased ultrasound power correlated with reduced particle size, altered protein structure, and higher protein recovery. Moreover, 400 W ultrasound significantly boosted antioxidant properties, as observed through ABTS and DPPH free radical assays at pH 11.5, indicating a correlation with inhibition percentage, as evidenced by increased radical scavenging capacity and reduced iron levels. Consequently, the combined application of alkaline pH adjustment and ultrasound processing significantly improved the sensory, functional, and antioxidant properties of proteins extracted from Siberian sturgeon.