Research Of Preparation And Detection Technology Of Soft-shelled Turtle Oil

Soft-shelled turtle is a high-value commercial species used as medicinal cuisine and food in daily life in many Asian countries,such as China,Korea and Japan.Soft shelled turtle can be served as one of the nutrient-dense food,which is rich in EPA,DHA,?-linolenic acid and other physiological active substances.It also can be used to anti-inflammatory,lower blood viscosity and cholesterol.In China,the large-scale farming of Chinese soft-shelled turtles has been growing rapidly to support the food industry,which produce abundant by-products.If it can be processed reasonably,environmental pollution and waste of resources would be greatly improved.The main results were as follows:1.The fatty acid composition,volatile compounds,sensory experiments were used to evaluate the extraction efficiency of five turtle oil extraction methods: enzymatic hydrolysis,organic solvent extraction,dilute alkali hydrolysis,ultrasonic-assisted organic solvent extraction and water bath extraction.The results showed that POV and AV of soft-shelled turtle oil acquired by dilute alkali hydrolysis and water bath extraction were higher,while the value of IV was lower,which indicated that the oxidative rancidity of these oil is serious.The ultrasonic-assisted organic solvent method was superior in extraction efficiency,while the obtained oil own light color,weak fishy smell,high content of health beneficial ?-3 PUFA.The analysis of the volatile compounds of oil showed that the content of aldehydes was higher in water bath extracted oil,which represents the strong fishy and oil smell.According to the above conclusions,the quality of soft-shelled turtle oil obtained by ultrasonic-assisted organic solvent method was obviously superior to other four methods,which provides a theoretical basis for the further optimization of the soft-shelled turtle oil extraction method.2.Hydrophilic interaction chromatography(HILIC-MS)was used as an accurate technique to extract,characterize and quantify the phospholipids in three strains of soft-shelled turtle oil.The extraction conditions of soft-shelled turtle oil were optimized as follows: 50? extraction temperature,2 mL elution solvent volume,30 min extraction time.A total of 22 PC molecular species,23 PE molecular species and 10 PI molecular species were detected by HILIC-MS in QXW,ZXH and ZWE.After optimizing the mobile phase,the phospholipids molecular species were quantified by the results of single ion current response of XIC function and the normalization of relative content.Furthermore,in principle component analysis(PCA),these soft-shelled turtle samples were well clustered into three statistically significant groups.The lipid composition of three soft-shelled turtles were significantly different,and m/z 790,818,866 could be used as potential markers for the differentiation of each strain of soft-shelled turtle according to the loading plot.3.The volatile compounds of soft-shelled turtle oil was analyzed by new laser-assisted desorption combined with headspace solid phase microextraction-gas-chromatography-mass spectrometry.53 volatile compounds were detected in soft-shelled turtle oil under optimal conditions of 10 W laser irradiation power,5 min irradiation time and 3 g sample,including 11 aldehydes,10 alcohol,11 ketones and 5 other volatile compounds.The content of volatile compounds which can produce the fishy and oil flavor,such as hexanal,furfural and 1-penten-3-ol,were high in turtle oil.In addition,some heterocyclic compounds which can be used to modify the overall flavor were also existed in the soft-shelled turtle oil.Meanwhile,compared with the traditional method of HAD-HS-SPME-GC/MS,LID-HS-SPME-GC/MS can be employed for rapid and efficient detection of volatile compounds in oil sample.4.The volatile compounds,POV,AV and the fatty acid composition were used as indicators to compare the antioxidant efficiency of three natural antioxidants during the storage,including tea polyphenol,VE and rosemary extract.The optimal amount of tea polyphenol,rosemary extract and VE are 0.06%,0.04% and 0.08% according to the optimization experiments.Gas chromatographic was employed to analyze the fatty acid composition with the aim of further explore the antioxidant ability of three antioxidants under the optimal amount,the result was as follows: 0.04% rosemary extract > 0.06% tea polyphenol > 0.04% VE.The above results can lay a solid foundation for further improve the stability of soft-shelled turtle oil and extend the shelf life.In this paper,the optimum extraction technology of soft-shelled turtle oil was investigated.The lipidomics of three stains of soft-shelled turtle oil was analyzed by HILIC-MS,while the volatile compounds and stability of the same samples were also studied.The above experiments are helpful for the development and production of soft-turtle oil,promotes the utilization of turtle by-products with higher economic benefits,which can be well applied to the composition analysis of three strains of soft-shelled turtle oil with good application prospect.