Isolation and characterization of collagen from the outer skin of squid (Doryteuthis singhalensis)

•Isolated collagen was characterized by type I and also higher imino acid content.•Doryteuthis singhalensis skin waste as a potential and rich sources of type I collagen.•Isolated collagen was higher thermal stability comparison to other fish skin collagens.•D. singhalensis collagen could be used as alternative source of mammalian collagen.•Isolated collagen could be used in foods, cosmetics and pharmaceutical industries.

Acid and Pepsin soluble collagens (ASC & PSC) were isolated from the outer skin of squid (Doryteuthis singhalensis) caught in the Indian waters with the yields of 56.80% for ASC and 24.60% for PSC, respectively. The total yield of ASC and PSC was 81.40% on the basis of lyophilized dry weight, which is higher compared to other sources. ASC and PSC were characterized as type I collagen, containing as α1 and α2 chains. The amino acids analysis of the ASC and PSC contained glycine (332 and 328 residues/1000 residues) as the major amino acid and had imino acids of 223 and 225 residues/1000 residues and the FTIR spectra confirmed that limited digestion by pepsin did not disrupt the triple helical structure of collagen. Thermal denaturation temperatures (Td) of the ASC and PSC measured by viscometry were 35.70 and 34.80 °C, respectively. The higher thermostable of squid skin collagen suggested that the possibility of its utilization as a substitute for commercial collagen. Squid skin collagen has potential for use as a supplementary source of collagen. Thus, collagen from squid skin could serve as an alternative source of collagen for further application in food, nutraceutical and pharmaceutical industries.

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