Establishing Identification Methods For Olive Oil Origin By High Throughput Spectrscopic And Polyphenol Liquid Chromatographic Fingerprints

Olive oil as a kind of high-grade edible oil containing a lot of unsaturated fatty acids and functional active ingredients is widely welcomed by consumers.With the spread of Mediterranean diet culture and the circulation of world trade,the production and processing of olive oil are expanding from traditional producing countries to nontraditional ones.Driven by commercial interests,counterfeiting events of the false origin are also more and more frequent,so it is of practical significance to carry out the study of origin identification.In this study,extra virgin olive oils originated from Italy,Turkey and Spain were used as raw materials.A high-throughput micro titer plate reader was used to obtain UV-Vis fingerprints of olive oil samples.The ultra-high performance liquid chromatography(UPLC)fingerprints of the polar polyphenols of olive oil were established by using the UPLC.These two fingerprints were respectively combined with chemometrics to construct the method of identification of olive oil.In addition,we optimized the traditional liquid-liquid extraction method of olive oil polar polyphenols by three factors: extraction solvent and concentration,extraction times and material liquid ratio.On this basis,a Box-Behnken experimental design was applied,the interactions of each factor on the polar polyphenols’ concentration of olive oil’s extraction were investigated and the optimal extraction condition was determined.The solid phase extraction method was optimized two factors: eluent solvent and eluant solvent.Also,the advantages and disadvantages of traditional liquid-liquid extraction and solid-phase extraction in olive oil polar polyphenols extraction were compared in dimensions.The results showed that the accuracy of prediction value of UV-Vis spectrum combined with PLS-DA was 97.92%,and that of UPLC fingerprint of polar polyphenols combined with PLS-DA was 89.54%.In conclusion,these two fingerprint methods both can provide reference for the identification of olive oil producing origin.The optimal conditions of liquid-liquid extraction were 80% methanol solution used as the extraction solution,3 extraction times,2.5 m L/g liquid-solid ratio.The theoretical total polar polyphenol concentration was 176 mg/kg.The optimized solid phase extraction condition was as follows: a diol-based column was selected as the SPE cartridge,n-hexane-cyclohexane(1:1,v/v)was used as the eluent solvent,and methanol was used as the eluant solvent to elute the SPE cartridge.The total polyphenol content of the actual extract was 170 mg / kg.Comparing the details and extraction effect of liquid-liquid extraction and solid-phase extraction on the extraction of polar polyphenols from olive oil,the solid-phase extraction method has a simpler operation,a higher repeatability,the shorter total extraction time,and is more suitable for the extraction of large numbers of samples.