| The large yellow croaker(Pseudosciaena Crocea)is also known as yellow croaker and cucumber fish.It is the main economic fish in China’s coastal waters and occupies an important position in China’s fishery economy.Because of its rich nutritional value and delicious taste,it is deeply loved by consumers.According to the 2018 China Fisheries statistical yearbook,the mariculture output of large yellow croaker reached 198,000 tons,of which the output of Fujian Province alone reached 165,400 tons,accounting for 84.75% of the country.Large yellow croaker roes accounted for 20-30% of the fresh weight of the fish,but they were not fully utilized as the main by-product.It has a broad market prospect because it is rich in nutrients such as n-3 polyunsaturated fatty acids(PUFAs).However,there are few studies on the extraction,purification,quality control and lipomics of large yellow croaker roe oil at home and abroad.Therefore,in this study,the enzymatic hydrolysis method was first used to extract fish roe oil and the extraction process was optimized.Then,the crude fish roe oil was refined.The quality and volatile components of large yellow croaker fish roe oil before and after refining were studied and compared,and finally,the intensive research was compared from the perspective of lipidomics.So as to provide theoretical basis for the realization of high value utilization of fish roes resources in Fujian Province.The main research contents and results are as follows:(1)The roe of large yellow croaker was taken as the research object,alkaline protease was selected as the best protease for extracting fish roe oil from large yellow croaker based on different enzymes,and the effects of different single factors on the extraction of large yellow croaker roe oil by alkaline protease were investigated.The extraction process was optimized by response surface methodology.The optimum extraction conditions were determined as follows: temperature 58.9 ℃,time 2.1 h and p H12.0.Under these conditions,the extraction rate of large yellow croaker roe oil was as high as 86.29±0.04%.(2)In this study,the fish roe oil of large yellow croaker was extracted by alkaline protease as the experimental material,and the refining experiments such as degumming,deacidifying,decoloring and deodorizing were performed in order.First,the degumming process was studied,and the effects of different degumming agents,degumming temperature,amount of degumming agent,and degumming time on the degumming effect were investigated.Second,the influence of the amount of alkali added,deacidification temperature,and deacidation time on the deacidification effect was investigated.Finally,the activated clay was mixed with activated carbon,and the effects of the added amount of the adsorbent,the reaction temperature,and the stirring time on the decolorization and deodorization effects were studied.The results showed that the best process parameters for degumming are: the addition of acetic acid is 2.0%,the degumming temperature is 65 ℃,and the degumming time is 1 min.The best process parameters for deacidification are: the amount of alkali added is 0.9%,the deacidification temperature is 70 ℃,and the deacidification time is 30 min.The best process parameters for decolorization and deodorization are: the mixed ratio of activated clay and activated carbon is 0.5: 1,the amount of adsorbent added is 8%,the decolorization and deodorization temperature is 75 ℃,and the reaction time is 15 min.(3)Fatty acid composition analysis,electronic nose,gas chromatography-ion mobility spectrometry(GC-IMS),and headspace solid phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS)were used to determine the quality,fatty acid composition and volatile flavor of fish roe oil before and after refining.The results showed that the content of DHA in PUFA increased after refining.It was found that ethanol,methane and sulfide had great changes in the response value of the sensor by electronic nose measurement.combined with HS-SPME-GC-MS and GC-IMS,it was found that the contents of carboxylic acids,aldehydes,alcohols,ketones and esters increased in varying degrees,while the contents of aromatic compounds,hydrocarbons and heterocyclic compounds decreased,and 2-butanone was only higher in fish roe oil before refining.(4)LC-MS lipidomics analysis was performed to evaluate the influence of purification on the large yellow croaker roe oil.The results showed that the overall expression pattern of lipids in the C1 group was significantly different from the JZ1 group.There were 43 differential lipids between the two groups,including 9 categories,and compared with JZ1 group,the lipid in C1 group was significantly lower than that in JZ1 group,and the lipid in the up-regulation were FAHFA 21: 2/26: 4,PC O-11: 0＿28: 0 and PC O-21: 0＿28: 0,the down-regulated lipids mainly include PI O-11: 0＿22: 3,FA 30: 5,FA 18: 2.FA 24: 6 and FA 20: 1.From the point of view of lipidomics,this study showed that the refining process had a greater influence on the lipid composition of large yellow croaker roe oil. |
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