Study On Ultra High Pressure Assisted Extraction Of Fish Oil And Enrichment Of N-3 PUFA

Tuna is mainly marketed in fresh and canned forms.The by-products produced during the main processing process account for more than 50% of the total weight,but these by-products are rich in fat and protein.In order to improve the utilization value of tuna by-products.This paper uses ultra-high pressure combined with enzymatic hydrolysis to extract tuna fish oil,and analyzes its physical and chemical properties and fatty acid composition,and explore the mass transfer mechanism of ultra-high pressure assisted extraction of fish oil.Then,using the extracted tuna fish oil as raw material,the ethyl ester type of fish oil was prepared by the alkaline catalysis method,the ultra-high pressure auxiliary urea inclusion method was used to enrich ethyl ester type of n-3 PUFA,the enrichment parameters were optimized.The physicochemical properities of the urea inclusion compound were characterized;the electronic nose was used to analyze the changes in the acid value,peroxide value and volatile odor components of ethyl esters type of n-3 PUFA during storage.The oxidation stability of ethyl ester type of n-3 PUFA was analyzed by differential scanning calorimeter and Rancimat oil oxidation stability tester.The research conclusion is as follows:(1)The ultra-high pressure combined with enzymatic hydrolysis method was used to extract tuna fish oil,and its technological parameters were optimized.Under the conditions of 200 MPa pressure,10 min holding pressure,1.0% enzyme addition,and 60 min digestion time,the extraction rate of fish oil can reach 99.60%;the sensory quality and physical and chemical properties of tuna fish oil extracted by ultra-high pressure combined with enzymatic hydrolysis have reached the first-class standard of crude fish oil;the saturated fatty acids in fish oil mainly include lauric acid(C14: 0),palmitic acid(C16: 0),and stearic acid(C18: 0),the content is 28.29%;saturated fatty acids mainly include palmitoleic acid(C16: 1,n-7),oleic acid(C18: 1,n-9),and peanut oleic acid(C20: 1,n-9),the content is 32.70%;polyunsaturated fatty acids mainly include EPA(C20: 5,n-3)and DHA(C22: 6,n-3),with a content of 33.96%.The ultra-high pressure technology generates a pressure difference and a reverse pressure difference through the action of pressure,causing structural changes such as loosening and breaking of biological tissue cells,thereby improving the extraction rate of fish oil.(2)The ultra-high pressure assisted urea encapsulation method was used to enrichethyl ester type of n-3 PUFA,the mathematical model of the process was established,and the enrichment process parameters were optimized.Under the condition that the ratio of urinary ester is 3.5: 1,the ratio of alcohol to urea is 2: 1,and the treatment pressure is 275 MPa,the content of DHA and EPA of ethyl ester of n-3 PUFA reaches 56.18%.Infrared spectroscopy,differential scanning calorimeter and field emission scanning electron microscope were used to analyze the urea inclusion complex,which proved that ultrahigh pressure can promote the formation of urea inclusion complex.(3)The electronic nose was used to analyze the changes of acid value,peroxide value and volatile odor components during storage of ethyl ester type of n-3 PUFA.Under the low temperature environment of-20 ? and 4 ?,the volatile components of fatty acid ethyl ester did not change significantly during storage.Under the environment of 25 ?,the volatile odor components of ethyl ester type of n-3 PUFA changed significantly during the storage period,and the change of volatile odor components was consistent with the change trend measured by the peroxide value and acid value.(4)The oxidation stability of ethyl ester type of n-3 PUFA was analyzed by Rancimat method and DSC thermal analysis method.According to the Rancimat method,it is inferred that the shelf life of ethyl ester type of n-3 PUFA at 25 ? is 12 days.The DSC curve of fatty acid ethyl ester was analyzed by Flynn-Wall-Ozawa method and Kissiger method,and the activation energy of ethyl ester type of n-3 PUFA was calculated to be198.22 KJ/mol and 190.64 KJ/mol,respectively.Two methods have certain consistency.Therefore,the ultra-high pressure technology is suitable for assisting the extraction of fish oil and enrichment of ethyl ester type n-3 PUFA.