Chincmys Reevesii Lipids Analysis Based On UPLC-qTOF-MS Technolgy And Oxidation Evalutaion

In order to improve the benefit of the Chincmys reevesii processing industry,researching extraction,identification,oxidation evaluation and application of Chincmys reevesii viscera oil?CRVO?.We optimized the condition of aqueous enzymatic method,combined GC-MS and UPLC-ESI-Q-TOF-MS/MS methods to evaluate completely the nutritional value and applied to oil-in-water emulsion system to carry?-carotene,and explored suitable oil-in-water delivery system.The main achievements are as follows:1.According to optimized extraction parameters of CRVO by aqueous enzymatic method and got the highest oil extraction yield of 66.56±1.25%at the conditions of using alkaline protease,enzymatic time of 0.5h,enzyme concentration of 0.5%?w/w?,temperature of 55?,pH7 and solid-liquid ratio of 1:4.A total of 16 fatty acids including isomers were detected in the lipids of muscles,viscera,fat mass and eggs by GC-MS,and the highest content fatty acid was c18:1n-5.In addition,a certain amount of EPA?0.29%⁰.6%?and DHA?0.36%⁰.53%?were also detected in CRVO.The unsaturated fatty acid content?70.49%⁷9.62%?of CRVO was calculated.A total of139 lipid components were detected by UPLC-ESI-Q-TOF-MS/MS analysis,including4 diglycerides,7 phosphatidylcholine,3 sphingomyelins and 125 triglycerides.Moreover,the principal component analysis?PCA?showed that the lipid compositions of the fat mass was similar to the viscera,but different from other parts.2.With the process of accelerated oxidation at 60?,the free radical content increased constantly.The content of free radicals and POV values and TOTOX value had good linear relationship?R²=0.9302 and R²=0.9476 respectively?by fitting of line.During the process of accelerated oxidation at 60?of lipids,there were no relaxation significant between low field nuclear magnetic resonance?LF-NMR?T2 relaxation characteristics time and peak area ratio with the traditional oxidation index.With the process of accelerated oxidation at 90?,the free radical content increased in the oxidation of CRVO in a short time,and then decrease quickly.electron spin resonance technology is not very good to evaluate CRVO oxidation process of oxidation rate faster,high degree of oxidation.low field NMR showed a good linear relationship between T₂₃ and acid value?AV?,indicating that T₂₃ could better predict the change of acid valence in the oxidation process of CRVO.By the composition of fatty acid,during60?oxidation process,the content of DHA and EPA declined significantly,and other fatty acids contents have no change significantly;at 90?oxidation,the contents of DHA and EPA rapidly declined,and oleic acid and linoleic acid content decreased significantly.3.Lecithin?LEC?emulsion had the worst stability at different ionic strength,whey protein isolate?WPI?and gum Arabic?GA?emulsion had better physical stability at different ionic strength.Moreover,the salt ion concentration had no significant effect on the degradation of?-carotene.Under different pH conditions,WPI emulsion is extremely unstable at pH5,and obvious stratification was observed.?-carotene degradation is accelerated when pH is acidic,and all of three emulsifiers had limited protection against degradation of?-carotene at different pH.Temperature can significantly affect the oxidation of emulsion.The oxidation degree of WPI is lower than that of GA emulsion and LEC emulsion,so the protection of?-carotene is higher.The order of digestibility of the three emulsions was as follows:GA>WPI>LEC;The digestion rate of GA emulsion and WPI emulsion were faster than LEC emulsion.