Study On Soybean Quality Evaluation Technology Based On Near Infrared Spectroscopy

Edible vegetable oil is the basic raw material and the most basic living material in modern food industry.The triglycerides that from oil fatty acid and glycerol of edible vegetable oil by acetylation reaction are stable,and their content up to 95%.The composition of most of the triglycerides and fatty acids are similar in different varieties of vegetable oil,which main including palmitic acid,stearic acid,arachidic acid and other saturated fatty acids,oleic acid,linoleic acid,linolenic acid and other unsaturated fatty acids.This paper studied the composition and content of fatty acids and triglycerides mainly through three instruments detection methods(GC?HPLC-ELSD?Triple-TOF-MS/MS),and analyzed by chemometrics.Meanwhile,on the basis of the above,the authenticity of vegetable oil was characterized which provide a method for the identification of plant oil adulteration.Firstly,the qualitative analysis of fatty acid composition of sesame oil,rapeseed oil,soybean oil,peanut oil,sunflower oil and maize oil were analyzed by gas chromatography,and the area normalization method was used for quantitative analysis.There were differences between different vegetable oils at fatty acids level.Oleic acid and linoleic acid content is equally matched in sesame oil,the range of oleic acid and linoleic acid content were 35.88%to 42.83%and 38.70%to 44.32%,respectively.The saturated fatty acid content in rapeseed oil was the lowest among the six vegetable oils.Linoleic acid content is about two to three times higher than the oleic acid content in soybean oil.The content of more than twenty carbon fatty acids in peanut oil is higher than that of other vegetable oils.The content of arachidic acid,behenic acid and lignoceric acid were 1.25%to 2.06%,2.22%to 3.55%and 1.23%to 1.56%,respectively.Sunflower oil and maize oil show similar fatty acid compositions and contents with sesame oil.Principal component analysis was performed on the six kinds of vegetable oils that based on fatty acid compositions and contents,three principal components of the cumulative contribution rate reached 97.53%which was based on the ratio of fatty acids.The result is better than those of PCA based on fatty acid composition and content.The results show that the fatty acids of different vegetable oils have a characteristic map in composition and content,and can be used to characterize the authenticity of vegetable oils.Secondly,high performance liquid chromatography coupled with evaporative light scattering detection and high performance liquid chromatography tandem quadrupole time of flight mass spectrometry can be used to determine the triglyceride with different carbon equivalent in vegetable oils.The basic ECN profile can be determined by the separation of triglyceride in vegetable oils through HPLC-ELSD.The six kinds of vegetable oil mainly contain the triglyceride of ECN42,ECN44,ECN46 and ECN48;the ECN composition of high erucic acid rapeseed oil is more complex than the ECN composition of low erucic acid,high erucic acid oil contains the triglycerides of ECN54 and ECN56.The contain of triglyceride of ECN50 from peanut oil is higher,this is because the saturated fatty acid in peanut oil which carbon content are more than twenty percent,such as arachidic acid,behenic acid and tetracosanoic acid,are much higher than other vegetable oils.Therefore,according to the characteristics of different ECN triglycerides in vegetable oils can also be used to characterize the authenticity of vegetable oils.At the same time,Triple-TOF-MS/MS can be used for the accurate determination of triglycerides which have same ECN,analyzing the mass spectrum data and determining the types of triglycerides,which can provide a theoretical basis for the characterization of plant oil and the identification of adulteration.Lastly,the fatty acid composition and content of pure sesame oil which mixed with different proportions of rapeseed oil,soybean oil,sunflower oil and corn oil were studied,and different fatty acid ratio models were established.A two-dimensional model of sesame oil adulterated with rapeseed oil and soybean oil was established by palmitic acid/stearic acid(P/S)and oleic acid/linolenic acid(O/Ln),the model can identify 5%rapeseed oil or soybean oil adulteration.Because of the composition and content of fatty acids in sunflower oil and corn oil are similar to those insesame oil,a three-dimensional model of sesame oil mixed with sunflower oil or corn oil was established by oleic acid/palmitic acid(O/P),linoleic acid/stearic acid(L/S)and oleic acid/palmitic acid + linoleic acid/stearic acid(O/P+L/S),the adulteration detection limit is 15%.