Salmon Skin Acid-Soluble Collagen Produced by A Simplified Recovery Process: Yield, Compositions, and Molecular Characteristics

Abstract

Acid-soluble collagen (ASC) is generally extracted by acid solubilization, followed by precipitation and dialysis. Such a process is typically time consuming and tedious, especially for dialysis. A simplified recovery process based on water washing/centrifugation of collagen pellets to replace dialysis was successfully developed. An ASC pellet from salmon (Oncorhynchus nerka) skin was obtained by salt precipitation (2.6 M). The pellet was washed with 50 volumes of distilled water (DW) and centrifuged for 0–3 cycles before lyophilization. As the washing cycles augmented, decreases (p < 0.05) in the NaCl content with a coincidental increase (p < 0.05) in the hydroxyproline content were attained. Similar protein patterns between all of the ASC samples, regardless of washing cycles, were noticeable. All of the ASCs were classified as type I collagen. FTIR spectra revealed that ASC possessed a triple helical structure with sufficient washing cycles. ASC washed with DW for three cycles (ASC-3C) was selected and characterized. ASC-3C showed high extraction yield (36.73%) and had high lightness. It exhibited high thermal stability (Tmax = 37 °C) and had an ordered phase structure. Glycine and imino acids were the dominant amino acids in ASC-3C. Therefore, a simplified recovery process could be adopted for ASC production, in which the shorter time was used without adverse effects toward ASC.