Effects Of Physical Processing On The Structure And Functional Properties Of Mussel (Mytilus Edulis) Protein

Mussel is one of the most important farming shellfish in China.Mussels are favored by consumers due to their high nutritional value,abundant protein content,and superior essential amino acid content and species than meat protein.At present,mussels on the market are mainly based on fresh sales,and the industrial utilization is extremely low,resulting in a great waste of resources.In this study,three kinds of environmentally-friendly and efficient physical processing methods,such as ball milling,high-pressure homogenization and ultrasonic were used to improve the structure and functional properties of mussel protein,making it better applied in the food industry.The main contents are as follows:(1)Ball milling treatment: The mussel protein isolate was treated by ball milling treatment(20 Hz,0,5,10,15,20 min).After ball milling treatment,the mussel protein bands of SDS-PAGE have no changed.The total sulfhydryl content did not change significantly,the free sulfhydryl content and the surface hydrophobicity of the protein was increased.Therefore,Ball-milling treatment did not change the primary structure of mussel protein,but caused changes of secondary structure.The tertiary and quaternary structure also changed.After 20 min of ball-milling treatment,the whiteness and oil-binding capability of mussel protein significantly improved from 13.67 to 26.62 and 43.8% to 196.0%,while the protein solubility and water-holding capability of mussel protein significantly decreased from 74.9% to 53.1% and 215.7% to 90.9%.Ball-milling treatment increased the in vitro digestibility significantly.(2)High pressure homogenization treatment: The mussel protein isolate was treated by high pressure homogenization treatment(20,40,60,80,100 MPa,3 cycles).The results showed that the homogenization treatment did not change the mussel protein bands of SDS-PAGE,but significantly changed the content of a-helix,β–sheet and β-turn.The free(3)Sulfhydryl group firstly increased and then decreased,and the values of surface hydrophobicity were increased.Therefore,High pressure homogenization treatment did not modify the protein profiles of mussel protein isolate,but caused changes in secondary,tertiary and quaternary structure.High pressure homogenization treatment improved functional properties of mussel protein isolate such as solubility,foaming ability,emulsifying activity and stability.(4)Ultrasound treatment: The mussel protein isolate was treated with ultrasound probe(20 kHz)at 200,400,and 600 W for 18 and 36 min.Ultrasound treatment did not modify protein profiles of MPI,but caused changes in secondary,tertiary,and quaternary structure.After ultrasound treatment,the solubility of mussel protein isolate was improved from 20.0% to 42.8%.The value of zeta potential was increased from 4.10 mV to 22.17 mV.And the surface hydrophobicity of the protein was increased from 113.81 to 178.22.Furthermore,as the ultrasonic power and time increasing,the molecular size of the protein was decreased;the emulsifying properties(emulsification activity and emulsion stability)and foaming properties(foaming ability and foaming stability)of the protein are also significantly improved.