Study On The Structure And Function Of The Antarctic Krill Proteins Regulated By Ultrasound-coupled Succinylation Modification

Antarctic krill（Euphausia superba）is one of the largest and most successful single biological resources on earth.The whole krill contains 77.9-83.1%water,0.4-3.6%lipid,11.9-15.4%protein and about 2%chitin,considered to be a rich and suitable source of aquatic protein and lipids.Its proteins contain essential amino acids required by adults and produce peptides with antioxidant antibacterial and anti-osteoporosis activities,which is a potential fishery resource.However,Antarctic krill is currently widely used as animal feed,making full use of Antarctic krill to develop protein-containing foods is of great significance in the food industry.Although the nutritional appeal of the Antarctic krill proteins is important,their physicochemical functional properties are equally important,the demand for Antarctic krill products is increasing,but some functions of the proteins are lacking.For example,the low solubility of the Antarctic krill proteins at neutral p H limits their widespread application in the food industry.This article took the Antarctic krill protein as the main material,and used physical-chemical modification to explore the effect of modification on the physicochemical and functional properties of Antarctic krill.To study the application prospect of curcumin emulsion,this study provided a new idea for designing functional foods and opened up a new avenue for the application of Antarctic krill in the food industry.The main research contents and results are as follows:（1）Physicochemical and functional properties of succinylated modified Antarctic krill proteinThe Antarctic krill proteins was modified by chemical succinylation,and the effect of succinylation on the physicochemical properties of the Antarctic krill proteins was studied.The results showed that the structure of AKPs changed greatly with the increase of succinylation degree.The hydrophobicity of particle size decreased,the net negative charge on the surface increased,and the functional properties such as solubility,emulsifying,and emulsifiying stability were improved.In addition,the emulsion stabilized by S_0.5-AKP can better encapsulate curcumin,and further improved the light,heat and salt stability of curcumin,while reducing its degradation rate.The above results suggested that succinylation was an effective means to improve the physicochemical and functional properties of the Antarctic krill proteins.（2）Physicochemical and functional properties of the Antarctic krill proteins modified by ultrasound-assisted succinylationThe Antarctic krill proteins was modified by ultrasonic-assisted succinylation.The effects of two modification methods on the physicochemical and functional properties of the Antarctic krill proteins were studied,and the curcumin emulsion stabilized by the modified protein was used as a natural Fresh-keeping coating,which aimed to study bactericidal ability combined with photodynamics.The results showed that ultrasound-assisted succinylation could reduce the particle size of the Antarctic krill protein,increasing the negative surface charge,and further improve the functional properties such as solubility and antioxidant activity of the Antarctic krill proteins.In addition,the combination of photodynamic treatment can effectively decelerat the proliferation of the bacterials on the surface of salmon.The above results indicated that the combination of ultrasound and succinylation could further improve the physicochemical and functional properties of the Antarctic krill proteins,which developed a new way for the application of Antarctic krill in the food industry.（3）Exploring the ability of the curcumin emulsion stabilized by the Antarctic krill proteins combined with photodynamics on salmon surface colonies.The curcumin emulsion stabilized by the modified protein which used as a natural preservative to explore its effect on the preservation of salmon by coating.The quality of salmon stored at 4°C was systematically analyzed by microbiological,physical and chemical methods.The results showed that the curcumin emulsion coating can effectively reduce the growth rate of microorganisms in salmon,greatly reduce the production rate of TBARS,and delay the accumulation of free fatty acids after combining with photodynamics.Photodynamics can also effectively delay the coloration.The changes and loss of moisture together protect the texture and organoleptic properties of the salmon.Therefore,curcumin emulsion stabilized by modified protein combined with photodynamic technology proved to be an effective means of bacteriostasis and preservation.