Isolation, Preparation, Properties And Application Of Collagen From Tuna Fish Skin

Collagen is a kind of biopolymer synthesized by animal cells.It is widely found in cartilage,skin and other connective tissues of animals.It has been widely developed and applied in food,medicine and cosmetics due to its unique physiological activity.Deep sea fish is a good source of collagen extraction.In this paper,the different extraction conditions of fish skin collagen were optimized by using tuna skin as raw materials.The physical and chemical properties and functional properties of the three collagens were analyzed and compared.The specific results are as follows:1.According to the extraction rate of collagen,the optimal conditions for different extraction methods of tuna skin collagen were determined by single factor and orthogonal experiments.Hot water method: extracting at a ratio of material to liquid of 1:20 and temperature of 70 ? for 7 h,the extraction rate is 62.4 %;acid method: extraction with acetic acid concentration of 0.5 mol/L,ratio of material to liquid of 1:20 and temperature of25 ? for 11 h,the extraction rate of 82.6 %;complex enzyme method: in the ratio of complex enzyme(neutral protease: trypsin)1:1.5,the ratio of material to liquid was 1:15 and the temperature was 35 ? for 6 h,and the extraction rate was 81.0 %.The extraction effect of acid method and complex enzyme method is obviously better than that of hot water method.2.The physicochemical properties and structure of the three collagens were studied separately.Ultraviolet absorption spectroscopy results showed that all three collagens have characteristic absorption peaks of collagen;fluorescence microscopy and infrared spectroscopy showed that the collagen extracted by the complex enzymatic method had been unraveled,and the other two collagens retained the complete triple helix structure.The results of amino acid composition analysis showed that all three collagens had typical amino acid composition of collagen,which accorded with the structural characteristics of type I collagen;differential scanning calorimeter results showed that the thermal shrinkage temperature of collagen extracted by acid method was 65 ?,and the complex enzyme method collagen did not undergo thermal contraction.3.The functional properties of three collagens were studied separately.The results showed that all the three collagens had good water absorption;the wettability of the collagen extracted by the complex enzyme method was better than the other two proteins;the oil absorption and foaming of the collagen extracted by the hot water method and the acid method were both better than the complex enzyme method.The results of molecular weight measurement showed that the relative molecular weight of collagen extracted by acid method was reduced to 11 kDa,and the molecular weight of collagen which extracted by complex enzyme method was 1.5 kDa.In summary,the acid extraction rate is the highest,but it will cause enviro nmental pollution;the compound enzymatic extraction rate is slightly lower,but it has higher biosafety,and the extracted collagen has good water absorption and wettability,and has certain oil absorption and foaming properties,which is suitable for further development and utilization.