Ultrasound accelerates pickling of reduced-sodium salted duck eggs: An insight into the effect on physicochemical, textural and structural properties

Abstract

In this work, high-intensity ultrasound (HIU) was used to accelerate the pickling of the reduced-sodium salted duck eggs (RSSDE). Meanwhile, it was evidenced that HIU treatment was also helpful to improve the overall quality of RSSDE. When the optimized HIU at 80 W was used, it resulted in favorably higher hardness (1.83 N), springiness (4.20 mm), and chewiness (4.83 mJ) of RSSDE whites, while the lowest hardness (1.12 N) of RSSDE yolks. The average particle size of RSSDE whites was significantly reduced (230.37 nm, 7.14%) as well. Apart from that, the absolute zeta potential and hydrophobicity were increased to −8.63 mV by 14.30% and 164.70 μg by 3.12%, respectively, attributed to the destruction of protein aggregation by cavitation effects. The oil exudation showed an obvious rising during the 14 days of the salting. HIU treatment at 80 W destroyed the emulsification state of lipid droplets and led to higher oil exudation (39.30%). The structural analysis of RSSDE proteins revealed marked alterations following HIU, with a reduction in α-helix and an increase in β-turn and random coil. The highest r-value reached 1.32 after HIU treatment at 80 W, which was attributed to the exposure of both tyrosine and tryptophan residues caused by the hydrophobic rearrangement of RSSDE protein. Scanning electron microscopy revealed that HIU altered the architecture of RSSDE proteins, resulting in more irregular pores. This work proved that HIU was a promising tool to shorten the salting period of RSSDE with much better quality.