Abstract:With Theragra chalcogramma skin as raw material and the extraction rate of collagen as the index，the optimal extraction process of collagen from Theragra chalcogramma skin by pepsin was determined by a single factor test and response surface optimization test.The basic properties of collagen from Theragra chalcogramma skin were identified by polyacrylamide gel electrophoresis，Fourier transform infrared spectroscopy，ultraviolet spectroscopy，and pre-column derivation-reversed phase high-performance liquid chromatography.In addition，the in vitro scavenging capacity and total reducing capacity of the collagen to hydroxyl free radicals，superoxide free radicals，and DPPH radicals were determined，so as to preliminarily studyits in vitro antioxidant activity.The results showed that the optimal extraction process of collagen from Theragra chalcogramma skin was as follows：enzyme of 1 500 U/g，reaction temperature of 41 ℃，reaction time of 3.9 h，and the collagen extraction rate under these conditions was 48.90%.The collagen extracted from Theragra chalcogramma skin by the process met the standard of type Ⅰcollagen products.At the same time，itsinfrared spectra contained five main collagen characteristic absorption peaks of amide，namely A and B，Ⅰ，Ⅱand Ⅲ.The ultraviolet absorption peak of type I collagen was obviously observed near 235 nm，and the Theragra chalcogramma collagen contained 17 kinds of amino acids in addition to tryptophan，with glycine，proline，alanine，glutamic acid，and histidine -rich in content.Finally，the in vitro antioxidant test showed that the extracted collagen from Theragra chalcogramma skin had strong antioxidant activity，and the half inhibitory concentration（IC50）of DPPH free radical，hydroxyl free radical，and superoxide free radical was 2.69，3.89 mg/mL and 4.42 mg/mL，respectively.