Rapid Quantitative Analysis of Ethanol and Prediction of Methanol Content in Traditional Fruit Brandies from Romania, using FTIR Spectroscopy and Chemometrics

Abstract

Fourier Transform Infrared (FTIR) spectroscopy in combination with chemometrics were applied for the quality control of 26 fruit brandies made by traditional technology in Romania. Firstly, for the identification and quantitative evaluation of methanol and ethanol in such samples, 4 mixtures of methanol and ethanol standard solutions and a spiked sample were fingerprinted in the 1200 - 950 cm-1 FTIR spectral range, identifying specific wavelength of 1020 and 1112 for methanol, 1047 and 1087 for ethanol. Then, the FTIR spectra of all brandy samples in the range 3500 - 750 cm-1 was registered and the methanol and ethanol concentrations were determined according to the previous calibration. By PCA (Principal component analysis) of FTIR areas (1170 -1000 cm-1), the variability and discrimination between samples was possible, discriminating between the biological and geographical origin of brandy samples. Based on peak areas and intensities, it was predicted the concentration of methanol in all samples, using Partial least squares regression (PLS). The correlation between FTIR and the reference method (GC-FID) was well correlated and significant (p<0.05). It was demostrated that FTIR technique offer a good prediction and statistical correlation with GC-FID technique for methanol quantification.

FTIR–ATR spectroscopy applied to quality control of grape-derived spirits

“…Indeed, Yucesoy and Ozen (2013) reported RPD values of 8.4 (r 2 = 98%) for methanol determination in Raki beverages using mid-IR spectral data samples. Coldea et al (2013) obtained good models between FTIR and GC-FID analyses for methanol quantification in fruit brandies made by traditional technology in Romania. Lachenmeier (2007), who analysed spirit drinks and beer and compared the reference methods with the spectral results from FTIR in combination with multivariate data analysis, obtained a correlation model with an r 2 = 99.7% for cross-validation and an r 2 = 98.1%…”

“…A similar region was used for methanol and ethyl acetate content evaluation in traditional fruit brandies from Romania using FTIR-ATR (Coldea et al, 2013).…”

Advances in Distilled Beverages Authenticity and Quality Testing

“…Actually, recent statistics place Romania as the first country in Europe for illicit alcohol consumption. Still, an exact amount of alcohol consumed cannot be given because, especially East European countries have their own tradition for homemade producing and consumption of distilled beverages [15][16][17][18][19][20].…”

“…The expensive reference methods tend to be replaced by simpler ones, non-destructive and easy to handle. The Fourier Transform Infrared Spectroscopy (FTIR) technique, in combination with chemometrics is a fast and reproducible way to identify the authenticity and adulteration of beverages [19,94]. As for wine, vinegar or olive oil, distilled beverages have also geographical indication denominations.…”

Characterization of ethanol concentrations at ultraviolet wavelength region

“…Nowadays, spectroscopy techniques has received much attentions in investigating the ethanol compound at Ultraviolet (UV) [1][2], Near-infrared [3][4] and Mid-Infrared (MIR) wavelength regions [5][6][7]. Spectroscopy offers repeatable and reliable results and has simple sample as compared to fiber optic sensors which is fragile and tedious to be fabricated [8][9].…”