The authentication of olive oil and its adulteration with lower priced oils are still serious problems in the olive oil industry. In this study, a method based on the intensity ratio of the Raman spectroscopy vibration bands, especially on the intensity ratio of the cis ( ==C-H) and cis (C=C) bonds normalized by the band at 1441 cm(-1) (CH(2)), was established to authenticate genuine/fake olive oil. These intensity ratios of the vibration bands given in the form of a two-dimensional chart allow first the discrimination between the various grades of olive oil and the seed oils and then the detection of olive oil fraud by the line of y = 0.7, which is observed under most experiments and dot charts. This method can reliably distinguish the genuine olive oils from the olive oils containing 5% (volume percentage) or more of other edible oils, such as soybean oil, rapeseed oil, sunflower seed oil, or corn oil. Compared to the traditional principal component analysis method, this method is more intuitive, more precise, and easier to use. Moreover, this method also has the advantages of simplicity efficiency and has no need for sample preprocessing, being especially suitable for on-site testing in field applications.

A method for the rapid determination of apple juice mingled with pear juice was proposed by a portable Raman spectrometer combined with chemometrics.The Raman shift for pear juice was the same as that for apple juice,and the functional groups and vibrational modes obtained for the Raman spectra of fruit juice were given.Slight differences of the Raman signals at 866 cm-1 and 1 126 cm-1 were found between the spectra of apple juice and pear juice,which may be due to the difference of fructose isomers content.Based on the presented method,19 apple juices and pear juices were easily distinguished by four different kernel functions of support vector machines(SVM).A mathematical model with SVM was established to analyze the content of pear juice added to apple juice.The relative errors for most of the analyzed samples were less than 10%.