Abstract: The effect of thermal treatment time on physicochemical properties and film-forming ability of acid-soluble collagen (ASC) from tilapia skin was investigated. No significant difference in UV absorption or molecular weight distribution of ASC was observed during thermal treatment. With increasing thermal treatment time, the specific viscosity of ASC was decreased, and the denaturation temperature and thermal transition temperature were decreased from 32.6 to 27.0 ℃ and from 38.15 to 29.19 ℃, respectively. When thermal treatment time was more than 10 min at 42 ℃, The results of turbidity experiments indicated that the ASC did not possess fibril-forming ability after 10 min treatment at 42 ℃. Furthermore, the fibril formation of natural collagen was also hindered by thermally denatured collagen. On the other hand, the tensile strength of collagen films was increased from 30.81 to 41.33 MPa, the elongation at breaks from 8.95% to 11.59%, and the transparency value from 2.42 to 3.33 with increasing thermal treatment time. Based on the results of scanning electron microscopy, it was found that the fibrous structure of collagen films was gradually converted to a wrinklelike structure during thermal treatment. From the above results, it could be concluded that the fibril-forming ability of ASC from tilapia skins was decreased after thermal denaturation, while the film-forming ability was increased.

Key words: acid-soluble collagen, thermal treatment, fibril-forming ability, film-forming ability, tilapia skin