Authentication of citrus peel oils from different species and commercial products using FTIR Spectroscopy combined with chemometrics

Abstract

Citrus fruit is widely grown in Indonesia. The skin of the fruit contains essential oils which can be used as aromatic ingredients in the perfume, pharmaceutical and culinary industries. Orange peel oil, extracted from different species, has different organoleptic qualities, specific gravity, refractive index value, acid number, ester number and solubility in 96% ethanol. This research aims to determine the differences in the essential oil components of sweet orange, lime and lemon peels and to determine the composition of commercial orange peel oil products. The method used to determine the differences in orange peel oil components is ATR-FTIR spectroscopy combined with two chemometric methods, PLS and PCA, to prove the differences quantitatively and qualitatively. The results of the PLS combination FTIR analysis showed that the most optimal wave number was shown in the 1450–1650 cm-1 area with an RMSEC value of 0.00553, then continued with PCA which showed the separation between samples. Results confirmed that the chemometric model effectively differentiated between essential oils from sweet orange, lime and lemon peels and those available on the market.