Quantifying Ethanol Content of Beer Using Interpretive Near-Infrared Spectroscopy

Abstract

On the basis of absorption measurements in the near-infrared (NIR) spectral range, a new method for the quantification of the ethanol content of beer is presented. Instead of the multivariate calibration models most commonly employed in NIR spectroscopic works, we use interpretive difference spectroscopy: Two wavelengths are selected according to the assignment of the absorption bands of the main substances of content of beer in the NIR region, and the difference between the absorbances at these wavelengths is used for ethanol quantification. Absorption spectra of the dominating beer ingredients are discussed and the calibration procedure with ethanol/water mixtures is shown. Robustness against the carbohydrate content of beer samples was demonstrated by analyzing solutions of ethanol and maltose in water. Validation of the method was performed with various beer samples with an ethanol concentration range between 0.5 and 7.7 vol %. The pertinent advantage of the procedure developed in this work is the indication that the results are independent from seasonal variations of the ingredients, which is of high interest for products with natural ingredients such as beer.

Extraction of Chemical Information of Suspensions Using Radiative Transfer Theory To Remove Multiple Scattering Effects: Application to a Model Multicomponent System

“…In the wavelength region considered, the first overtone bands of ethanol are found at around 1680nm (C-H), 1684nm and 1692nm (C-H 3 ) and bands due to asymmetric vibrations of CH 2 and CH 3 at around1714nm and 1719nm 28 . Calibration models were built using PLS regression both with and without applying pre-processing.…”

Fused adjacency matrices to enhance information extraction: The beer benchmark

“…A clear alcohol content (% alcohol by volume, ABV%) gradient is recognizable along PC1, as shown in Figure 3b. Ethanol content is therefore efficiently represented by PC1, whose corresponding loadings (not shown) are characterized by two intense ethanol bands within the region 2200-2400 nm [37].…”

“…Beer has been the object of several studies, mostly focused on a specific beer type aiming either at gathering the composition [24][25][26][27] or controlling the brewing process [28,29]. To achieve these aims very different analytical techniques have been applied: NMR [24,25,27,[30][31][32], LC-MS [30,33,34], GC-MS [35,36], vibrational (NIR and IR) [24,26,28,37] and UV-Visible [38] spectroscopies. The benchmark beer dataset consists of three data blocks obtained from different spectroscopic techniques: Visible (Vis), Near Infra-Red (NIR) and Nuclear Magnetic Resonance (NMR), the latter as interval-resolved data.…”

Near-infrared imaging of liquid mixtures utilizing multi-channel photonic crystal wavelength filters

“…As a test target, we chose aqueous alcohol solutions (ethanol containing water). Noninvasive and remote monitoring of the mixture ratio of such a liquid is one of the major applications for NIRS in fields, such as bio-ethanol production lines, brewing processes of alcohol beverages, and postpackaging management of liquid products [14][15][16].…”

“…3(b). Note that both pure and ethanol-included water have broad absorption bands in the vicinity of λ ∼ 1450 nm [15,18]. The PhCFs were designed to cover this band.…”