Detection of refined coconut oil as adulterant in virgin coconut oil using UV-Vis spectroscopy coupled with PCA

Abstract

Virgin coconut oil (VCO), one of the healthiest and most expensive edible oil, remains to be a target of adulteration with cheaper oils like refined coconut oil (RCO). UV-Vis spectroscopy was applied in combination with principal component analysis (PCA) for the differentiation and quantification of various concentration of RCO (20% increments, v/v) in VCO. The spectra of pure oils and mixtures, at 37°C, were collected using UV-Vis spectrometer. The pure VCO spectra has two observable crests between 200 nm to 300 nm range. In contrast, the RCO-adulterated versions of VCO have single peaks between 280 nm to 320 nm range. PCA was performed on spectral region 200 − 800 nm. Literature data and interpretation of the UV-Vis spectra indicate that the variation among adulterated samples could be explained by the different fatty acids present in VCO and in RCO. The first principal component scores may give insight about the purity of VCO. The variation in spectra among adulterated samples are amplified by their second principal component scores. It was concluded that UV-Vis spectra combined with PCA could detect and quantify the level of adulteration of VCO with RCO.