Abstract: Tilapia skin was pretreated with 0.006 mol/L phosphoric acid at a solid to liquid ratio of 50 g/L for 3 h at 4 ℃ to facilitate the separation of dermis and epidermis. The dermis was treated with 0.035 mol/L acetic acid at a solid to liquid ratio of 100 (g/L) for 6 h at 4 ℃ to fully swell it, washed and extruded to obtain collagen. The results showed that tilapia dermis collagen contained 7.9% of hydroxyproline, and the collagen yield was as high as 27.6% (on a dry basis). The collagen mainly consisted of α1, α2 and β polypeptide chains according to sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis, with maximum UV absorbance at 230 nm, complying with the characteristics of type Ⅰ collagen. The attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectrum proved the presence of the triple-helix structure of collagen. The thermal denaturation temperature and shrinkage temperature of the collagen were 29.2 ℃ and 55.0 ℃, respectively. The study provides an alternative approach to the extraction of high-quality collagen and consequently efficient utilization of fish processing byproducts.

Key words: tilapia skin, dermis, epidermis, swelling, extraction