Study On Walnut Oil Adultertion Based On Gas Chromatography Combined With Chemometrics

As an ideal health oil,walnut oil is more and more popular with consumers as people’s health awareness increases.The market price of walnut oil is much higher than that of other vegetable oils.In order to make huge profits,some unscrupulous operators mix cheap oil into walnut oil,which seriously damages the interests of consumers and disrupts the normal market economic order.Therefore,it is necessary to carry out research on oil fidelity technology.Therefore,this subject uses the GC method to systematically study the fatty acid composition and content changes of pure walnut oil and adulterated walnut oil.On this basis,combined with stoichiometric methods,a more complete qualitative and quantitative model of walnut oil adulteration is established.Provide technical support for walnut oil market supervision.The whole sample fatty acid composition,sn-2 fatty acid composition and triglyceride composition of walnut oil extracted from 87 kinds of walnuts from different regions of the country were analyzed to obtain the fatty acid composition and content range of walnut oil,providing data for walnut oil adulteration research.The whole sample fatty acid composition analysis method was used to analyze the changes in the fatty acid content of walnut oil before and after adulteration,and the detection limit was determined.When walnut oil is mixed with soybean oil,corn oil,sunflower oil,rapeseed oil,and peanut oil,the detection limits are 20%,10%,10%,10%,and 15%using pure walnut oil as the standard.Qualitative and quantitative analysis of walnut oil adulteration was carried out with the combination of fatty acid composition of the whole sample and stoichiometry.The results showed that the correct recognition rate of pure walnut oil by SVM method reached 100%,and the recognition rates of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil were 93.3%,93.3%,100%,100%,100%.The whole sample fatty acid combined with the PLS method has the best effect on the qualitative and then quantitative model of adulterated walnut oil.The R2 values of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil all reached above 0.96,and the RMSEP were 0.0477,0.0523,0.0365,0.0205,0.0366.The sn-2 fatty acid composition analysis method was used to analyze the fatty acid content of walnut oil before and after adulteration,and the detection limit was determined.When walnut oil was mixed with soybean oil,corn oil,sunflower oil,rapeseed oil,and peanut oil,the detection limits were 100%,50%,50%,15%,and 15%using pure walnut oil as the standard.The sn-2 fatty acid combined with stoichiometry was used for qualitative and quantitative analysis of walnut oil adulteration.The results showed that the correct recognition rate of pure walnut oil by SVM method reached 100%,and the recognition rates of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil were86.7%,86.7%,93.3%,100%,100%.The sn-2 fatty acid composition combined with the PLS method has the best effect on the qualitative and then quantitative model of adulterated walnut oil.The RMSEP of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil was 0.1947,0.1371,0.1220,0.0475,0.1272.The whole sample and sn-2 fatty acid fusion information combined with stoichiometry were used to qualitative and quantitative analysis of walnut oil adulteration.The results showed that,compared to the qualitative model of full-sample fatty acids and sn-2 fatty acids,the SVM qualitative model constructed by fusion information had the best prediction effect,and the accuracy of identifying pure walnut oil and adulterated walnut oil had reached 100%;The quantitative model of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil established by SVR method had R~2 above 0.70,and RMSEP were 0.1532,0.0919,0.0742,0.0630,0.0435.Combining triglyceride information with chemometrics for qualitative and quantitative analysis of walnut oil adulteration.The results showed that the correct recognition rate of pure walnut oil by SVM method reached 100%,but it was difficult to identify adulterated walnut oil 100%.Compared with the whole sample fatty acid and sn-2 fatty acid,the walnut oil adulteration quantitative model established by the combination of triglyceride information and PLS method has the best effect.The R~2 of walnut oil mixed with soybean oil,corn oil,sunflower oil,rapeseed oil and peanut oil was above 0.70,and the RMSEP were 0.1480,0.1402,0.1510,0.0702,0.0855.By comparing the whole sample fatty acid,sn-2 fatty acid and fatty acid fusion qualitative and quantitative models,it can be seen that the qualitative model established by the combination of fatty acid fusion information and SVM method has a correct recognition rate of 100%for pure walnut oil and adulterated walnut oil.The walnut oil adulteration quantitative model established based on the whole fatty acid combined with the PLS method has the best prediction accuracy.