| In recent years,people's requirements for quality of life are getting higher and higher,and the requirements for the quality and safety of foods such as edible oils and fats are also increasing.Therefore,more rapid,accurate and perfect use is needed in food quality and safety testing.The components contained in vegetable oil are complex,and it is difficult to effectively identify the various components contained in it by a single analytical detection technique.Therefore,it is necessary to combine various detection techniques to detect vegetable oil.Peanut oil and soybean oil are common edible vegetable oils in life.Therefore,this paper uses gas chromatography,solid phase microextraction and gas chromatography-mass spectrometry,ultra performance liquid chromatography-time-of-flight mass spectrometry(UPLC-Q-TOF/MS)and chemometrics to analyzes and identifies components of peanut oil and soybean oil.The main research contents are as follows:The first part describes the main chemical components of peanut oil and soybean oil and their related physiological activities.In addition,it also introduces the application of analytical and detection techniques commonly used at home and abroad in vegetable oil research.Including the application of physical and chemical methods,spectroscopy,chromatography,and chemometric methods in the analysis and identification of edible vegetable oils.The second part qualitatively and quantitatively the fatty acids,total phenols and tocopherols in peanut oil and soybean oil.The total phenol was determined by colorimetry,the fatty acid was determined by gas chromatography,and the tocopherol was determined by liquid chromatography.The results showed that the content of five fatty acids C16:0,C18:0,9cC18:1,9c12cC18:2,C20:3 was higherin peanut oil,and the content of fatty acid 9cC18:1 was up to 385.91~589.72mg/g.Secondly,the content of fatty acid 9c12cC18:2 is 199.0-1~388.69mg/g,the content of fatty acid C16:0 is 85.06~126.62mg/g,the content of C18:0 is 25.99~40.27mg/g,and the content of C20:3 is 15.08~28.54mg/ g.The content of five fatty acids C16:0,C18:0,9cC18:1,9c12cC18:2,9c12c15cC18:3 was higherin Soybean oil,the fatty acid9c12cC18:2 content is up to 444.41~537.80mg/g,followed by fatty acid 9cC18:1 The content is 154.60~216.30mg/g,the content of fatty acid C16:0 is 89.80~111.85mg/g,the content of 9c12c15cC18:3 is 54.95~93.87mg/g,and the content of fatty acidC18:0 is 33.12~45.93mg/g.It can be found that the content of 9cC18:1,9c12cC18:2 is higher in peanut oil and soybean oil.In addition,the content of fatty acid9c12c15cC18:3 in soybean oil is also higher.The content of polyphenols in peanut oil and soybean oil varied greatly,and the total polyphenol content in soybean oil was27.275~116.798?g/g.The total polyphenol content in peanut oil was23.081~79.492?g/g.Overall,the total phenolic content of peanut oil and soybean oil is higher in the crude oil than in the refined oil.Four tocopherols were detected in peanut oil.The total tocopherol content ranged from 30.963 to 50.694mg/100 g,of which ?-tocopherol was the highest,reaching 13.989~28.147 mg/100 g.Secondly,the content of ?-tocopherol was higher at 12.084~23.322mg/100g;?-tocopherol content is between 1.281~2.291mg/100g;?-tocopherol content is between0.991~1.655mg/100 g.Four tocopherols were also detected in soybean oil,and the total tocopherol content was between 98.963 and 152.943 mg/100 g,of which ?-tocopherol content was the highest,reaching 63.288~99.326mg/100g;followed by higher?-tocopherol content,between 23.99~49.563mg/100g;?-tocopherol content is between8.982~17.048mg/100g;?-tocopherol content is between 1.619~2.297mg/100 g.In general,the content of tocopherol in soybean oil is higher than that in peanut oil and the content of tocopherol in crude oil is higher than in the refined oil.In the third part,the volatile substances and their contents in peanut oil and soybean oil were analyzed by gas chromatography.The experimental results showed that 54 kinds of volatile components of peanut oil were identified,and 51 kinds of volatile components of soybean oil were identified.The content of2-ethyl-5-methylpyrazine,3-ethyl-2-5-dimethylpyrazine,2,5-dimethylpyrazine,2,3-di h-ydro-benzofuran,hexanal,furfural,heptane and 2-pentylfuran are higher in refined peanut oil;The content of2-ethyl-5-methylpyrazine,3-ethyl-2-5-dimethylpyrazine,2,5-dimethylpyrazine,2,3-dihydro-benzofuran,hexanal,furfural,guaiacol are higherin crude peanut oil.The content of2-(5-oxohexyl)-cyclopentanone,hexanal,(reverse,trans)2,4-heptadienal,limonene,trans-2-octenal,trans-2-nonenal are higherin refined soybean oil.The content of2-(5-oxohexyl)-cyclopentanone,hexanal,(reverse,trans)2,4-heptadienal,2,6,10-trimethyldodecane,2-butyl-2-Octenal,plant alcohol are higherin crude soybean oil.The relative contents of volatile oils of peanut oil and soybean oil were introduced into statistical analysis software SIMCA-P13.0 to construct PCA model.It was found that peanut oil and soybean oil can be clearly distinguished.There are significant differences between the volatile substances ofpeanut oil and soybean oil.Among them,the content of methylpyrazine,guaiacol,2,5-dimethylpyrazine,2-ethyl-5-methylpyrazine,3-ethyl-2-5-dimethylpyrazine,2,3-dihydro-benzofuran,trans-cinnamic acid,1-(2-hydroxy-5-methylphenyl)ethanone,2-pentylfuran are higher in peanut oil,the content of 1-hexanol,2-octyl methoxyacetate,(reverse,trans)2,4-heptadienal,octadecyl,1-phenyl-1-butene,quinaldine,2-(5-oxohexyl)-cyclopentanone,2-butyl-2-octenal are higher in soybean oil.In the fourth part,UPLC-Q-TOF/MS was used to analyze the methanol extracts of peanut oil,heat-processed peanut oil,metamorphic peanut oil,genetically modified soybean oil and non-GM soybean oil.Then peanut oil,hot processed peanut oil,metamorphic peanut oil,genetically modified soybean oil and non-GMO soybean oil were analyzed and identified by chemometrics software using principal component analysis,volcano map analysis and cluster analysis,qualitative analysis was carried out on the differential compounds in peanut oil,heat-processed peanut oil,metamorphic peanut oil,genetically modified soybean oil and non-GMO soybean oil.Finally,the discriminant model of five different vegetable oils was constructed by partial least squares discriminant analysis(PLS-DA).The established model is real and effective,and the prediction accuracy is up to 100%.It can be applied to the quality identification of different vegetable oils. |
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