Abstract
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•Collagen was pretreated with single frequency and tri-frequency ultrasound.•The pretreatment effectively improved the self-assembled quality of collagen.•The collagen is easier to digest and hydrolyze after the ultrasound pretreatment.•The polypeptides content in digestion of ultrasound treated collagen is 87.48%.
Chicken feet, aplenty by-products in the chicken industry, are rich in collagen and contain abundant amino acids so that it can be used as an important source for the collagen market. Pepsin-soluble collagen (PSC) was extracted from chicken leg skin and explored the effects of single- and tri-frequency ultrasound on the self-assembly and vitro digestion characteristics. By the diverging and tri-frequency ultrasound reactor, PSC was treated with 20 kHz/270w (C20H5m), 40 kHz/270w (C40H5m), 60 kHz/270w (C60H5m), 20/40/60 kHz/90w × 3 (CtH5m) for 5 min. Results showed that ultrasound could accelerate the process of collagen self-assembly, and 60 kHz/270w was the fastest. Microfiber diameters of C60H5m were 65–89 nm, which was significantly lower than the control without ultrasound (80–161 nm). The digestion results indicated polypeptides with relative molecular weights founded in the range 200–5000 Da were exceeded 85%. The final digested product had the highest content of oligopeptide, consistent rheological properties, and elastic behavior. The cavitation and mechanical of ultrasound have effects on the self-assembly process and collagen gel structure and digestion characteristics, which is of great significance for the development of the chicken industry and collagen market.