Determination of ethyl octanoate in Chinese liquor using FT-NIR spectroscopy

Abstract

To quantitatively detect ethyl octanoate in Chinese liquor, Fourier-transform near-infrared (FT-NIR) spectroscopy was performed in the present work, with 162 Chinese liquor samples selected from Luoyang Dukang Distillery. The chemical values of ethyl octanoate were determined by gas chromatography (GC), and spectral data from 12,000 to 4000 cm-1 were collected. The calibration model was established with partial least squares (PLS) regression, and then validated using internal cross-validation. The predictability of the model was further confirmed by the validation set as external validation. After comparing the effects of the models set up with sample data under different pre-processing methods, the model was built within the spectral region of 6101.7 - 5449.8 cm-1; based on the SNV pre-processing method which was selected as the optimal model. The coefficient of determination (R2) for cross-validation of the model was 0.9507, and the corresponding root mean square errors of cross-validation (RMSECV) was 3.91 mg L-1. The R2 for external validation was 0.9537, and the root mean square errors of prediction (RMSEP) was 3.62 mg L-1. The results demonstrated that using NIR spectroscopy to determine ethyl octanoate in Chinese liquor is feasible and can achieve satisfactory results.