Characterization of Acid- and Pepsin-soluble Collagens Extracted from Scales of Carp and Lizardfish Caught in Japan, Bangladesh and Vietnam with a Focus on Thermostability

Acid- and pepsin-soluble collagens (ASC and PSC) from scales of carp and lizardfish from temperate and sub-tropical countries were studied in regard to thermostability. SDS-PAGE revealed that ASC and PSC were classified as type I collagen, and the molecular weight of ASC was greater than that of PSC. Both types of collagen from sub-tropical fish scales contained greater imino acids compared to those from temperate fish scales. Carp from Japan and Bangladesh showed similar thermal stability, but lizardfish from Vietnam showed higher stability than lizardfish from Japan for both collagen types. Overall, PSC possessed a slightly lower denaturation temperature than the corresponding ASC, suggesting that a relationship between thermostability and the molecular mass of collagen, as observed in SDS-PAGE, might exist. Maximal solubility was noticed at acidic pH (1-4) and solubility obviously declined at a high salt concentration (>2 %). ASC and PSC from these fish scales could be applicable to the food industry in place of mammalian collagens.