Partial least squares−near infrared spectrometric determination of ethanol in distilled alcoholic beverages

Abstract

In this study, using near infrared (NIR) spectrometry-partial least squares (PLS) calibration model was used for the determination of ethanol content in distilled alcoholic beverages. In NIR, 1660–1720 nm, the PLS modeling and analysis made use of 24 standards which contain 2–15% (w/w) ethanol with 0.1–1% (w/w) methanol. One-half was used for calibration and the other half for validation. Derivative, mean centering and subtracting minimum value were used as data treatment techniques for noise reduction and baseline correction. Mean centering has given the best partial least squares model with R² = 0.999 and root mean square error of prediction (RMSEP) = 0.06 for ethanol and R² = 0.929 and RMSEP = 0.08 for methanol, respectively. The percentage recovery obtained for ethanol and methanol ranges from 97–98% (w/w). The developed method produced good agreement with reference method, gas chromatography.

KEY WORDS: Distilled alcoholic beverages, Ethanol, Methanol, Near infrared spectrophotometry, Partial least squares, Chemometry, Gas Chromatography

Bull. Chem. Soc. Ethiop. 2017, 31(2), 201-209.

DOI: http://dx.doi.org/10.4314/bcse.v31i2.2