Rapid authentication measurement of cinnamon powder using FT-NIR and FT-IR spectroscopic techniques

초록

Owing to the worldwide demand for cinnamon spices, true cinnamon (Cinnamomum verum) powder is often being adulterated with another inferior quality of cinnamon known as cassia cinnamon (Cinnamomum aromaticum). This study employed Fourier transform near-infrared (FT-NIR) and Fourier transform infrared (FT-IR) spectroscopic analysis to determine the spectral differences in assorted percentages after mixing with adulterants. The absorbance spectra of total 195 samples were collected of true, cassia and various adulterated samples (5-50 wt % adulterate) with 15 replicates for each sample. Independent component analysis was integrated with FT-NIR and FT-IR spectroscopic data for the detection of an unknown cinnamon mixture as a blind source separation tool that revealed distinctive peak difference. The partial least square regression (PLSR) models with spectral preprocessing methods were applied to predict the presence of cassia cinnamon in true cinnamon powder. The PLSR model for the FT-NIR and FT-IR data predicted adulteration with an R-p(2) of 0.97 with a root-mean square error of prediction (RMSEP) of 2.2% and an R-p(2) of 0.96 with an RMSEP of 2.5% respectively after applying Savitzky-Golay 2nd derivative as preprocessing. Thus, the predictive value of FT-NIR data was greater than the FT-IR data. In addition, the ratio of standard error of performance to standard deviation (RPD>2.5) and the range error ratio (RER>10) values were also calculated for both of the spectroscopic techniques to predict model accuracy for the independent validation set. The beta coefficient curve from the PLSR models also revealed the spectral peak differences among the samples concentrated with various amount of cassia cinnamon powder. These methods proved that FT-NIR and FT-IR spectroscopic techniques combined with multivariate analysis could be utilised as a controlled procedure or as an alternative rapid detection method to identify adulterated cinnamon powder.

키워드