Diluted Acetic Acid Softened Intermuscular Bones from Silver Carp (Hypophthalmichthys molitrix) by Dissolving Hydroxyapatite and Collagen

Intermuscular bones (IBs) pose physical hazards that threaten consumer health and food safety. This study aimed to investigate the mechanism of softening IBs from silver carp with diluted acetic acid. IBs (separated from muscle) and fillets (without removing IBs) were treated with diluted acetic acid. Analyses of sensory attributes and the hardness of treated IBs indicated that diluted acetic acid (<10 mmol/L) could soften IBs effectively. Additionally, 0.5 mmol/L acetic acid softened IBs within fillets without significantly affecting the texture and flavor of fillets. Analyses of microstructure, minerals (calcium and phosphorus) and collagen content, and the Fourier transform infrared (FTIR) spectra of IBs indicated that acetic acid broke connections (formed by collagen that shared hydroxyl groups) between collagen molecules, and between collagen and hydroxyapatite (HAP), thus inducing the dissolution of collagen and HAP. The dissolution of HAP contributed more to IBs softening than collagen.