Determination Of Ethanol In Beer Research Articles

Analysis of Ethanol in Beer Using Gas Chromatography: A Side-by-Side Comparison of Calibration Methods

An important objective of any analytical chemistry course is for students to generate and interpret data from the analysis of complex, real-world samples in order to assess the effectiveness of the analysis method, including the calibration. In this laboratory exercise, students directly compare calibration methods (external standards and standard addition, both with and without an internal standard) for the determination of ethanol in beer using an affordable benchtop gas chromatograph. The experiment allows students to evaluate the advantages and disadvantages of each method (including accuracy, precision, and sample preparation) using their own data.

Determination of Ethanol in Beers Using a Flatbed Scanner and Automated Digital Image Analysis

A new, simple, and low-cost method is proposed to determine ethanol content in beer samples. The method is economical and environmentally friendly because it uses low-cost materials based on natural indicators and generates only 200 μL of waste per test. The method is based in the reaction of ethanol with potassium dichromate in acid media generating Cr3+; 100 μL of K2Cr2O7 0.2 mol L−1 in sulfuric acid 20%, v/v was placed in wells of a 96-micro-well plate, then, 50 μL of samples or standards were placed in each well, after 1 h incubation at 60 °C, a digital image of the plate was obtained using a flatbed scanner, and RGB values were extracted automatically from all wells in less than 5 min using ImageJ’s plugin “ReadPlate.” The standard calibration plot was linear for an ethanol content ranging from 0.4 to 2%, with limits of detection and quantification of 0.09% and 0.27%, respectively. Ethanol content determined in beer samples with proposed method agree with those obtained with the microplate reader and with those claimed in labels. Thus, this method can be especially advantageous for countries were available resources for analytical equipment investments are scant.

A highly sensitive enzyme catalytic SERS quantitative analysis method for ethanol with Victoria blue B molecular probe in the stable nanosilver sol substrate

Using AgNO3 as precursor, a stable silver nanosol with strong SERS activity was prepared rapidly by light-wave procedure. A highly sensitive SERS quantitative analysis method for ethanol was developed, coupled the alcohol oxidase catalytic reaction with the Fe2+ catalytic reaction that the produced hydroxyl radicals not only oxidized the silver atoms on the nanosilver surface to form more dispersed and small size nanosilvers with weak SERS effect, but also oxidized the molecular probe Vitoria blue B (VBB) to fade. With the increasing of ethanol concentration, the more nanosilver and probe molecules were oxidized, resulting in SERS intensity decreasing at 1615 cm−1. The decreased SERS intensity was linear to ethanol in the range of 0.008–0.40 mg/L, with a detection limit of 3 μg/L. This method was applied to determination of ethanol in beer and serum samples, with satisfactory results.

A membraneless gas diffusion unit: Design and its application to determination of ethanol in liquors by spectrophotometric flow injection

This work presents new design of a gas diffusion unit, called ‘membraneless gas diffusion (MGD) unit’, which, unlike a conventional gas diffusion (GD) unit, allows selective detection of volatile compounds to be made without the need of a hydrophobic membrane. A flow injection method was developed employing the MGD unit to determine ethanol in alcoholic drinks based on the reduction of dichromate by ethanol vapor. Results clearly demonstrated that the MGD unit was suitable for determination of ethanol in beer, wine and distilled liquors. Detection limit (3S/N) of MGD unit was lower than the GD unit (GD: 0.68%, v/v; MGD: 0.27%, v/v). The MGD design makes the system more sensitive as mass transfer is more efficient than that of GD and thus, MGD can perfectly replace membrane-based designs.

Graphite–Teflon composite bienzyme amperometric biosensors for monitoring of alcohols

Composite graphite–Teflon electrodes, in which the enzymes alcohol oxidase (AOD) and horseradish peroxidase (HRP), as well as the mediator ferrocene, are incorporated into the electrode matrix, are reported for the reliable monitoring of alcohols in food and beverages. The bienzyme electrodes are constructed by simple physical inclusion of the enzymes and the mediator in the bulk of graphite–70% Teflon rigid cylindrical pellets. The composite biosensors are robust and reusable because of the renewability of the electrode surface by polishing. Reproducible amperometric responses at 0.00 V were obtained with different electrodes constructed from the same pellet and from different pellets. No significant loss of the enzymes activities was found after at least 3 months of storage at 0 °C. The detection limits obtained by amperometry in stirred solutions can be advantageously compared with those achieved with commercial sensors for alcohols. The bienzyme electrodes are suitable to be used under flow-injection conditions, as well as for amperometric detection in HPLC. The bioelectrodes were employed for the determination of ethanol in beers, wines and liquors, using both batch- and flow-injection modes, and for the determination of methanol in wines and liquors by HPLC with amperometric detection. Only a dilution of the beverages was needed as sample treatment in all cases.

Determination of ethanol in beer by flow injection dual-pulse staircase voltammetric detection

Dual-pulse staircase voltammetry (DPSV), was studied for the determination of ethanol in beer using electrochemical detection and flow injection (FI). As the method did not require deaeration and had a sufficiently wide linear range to cover the area of application, it could be used for the direct determination of alcohol without any prior separation. Under the optimized conditions, in a 0.10 mol l–1 NaOH solution, the repeatability (relative standard deviation 1.9%, mean = 0.03 mol l–1 and n= 8), linear range (0.01–10 mol l–1) and detection limit (0.0006 mol l–1, 3s of the background current) of the developed method were found to be satisfactory for the determination of ethanol in beer samples by FI with a flow rate of 0.5 ml min–1, an injection volume of 100 µl and a maximum sample throughput of 60 samples per hour, prior to the overlapping of the FI peaks. No interfering effect was observed for additives at the concentrations commonly encountered in beer samples and the method was found to give similar results to the reference AOAC method. The method developed provides a general method for the electrochemical detection of alcohols and other organic compounds with alcoholic hydroxyl groups.

DETERMINATION OF ETHANOL IN BEER BY DIRECT INJECTION GAS CHROMATOGRAPHY: A COMPARISON OF SIX IDENTICAL SYSTEMS

Six identical gas chromatographic (GC) systems from the same manufacturer were evaluated for the determination of ethanol in beers. Each system was assessed for detector linearity and drift using standard ethanol solutions. Repeatability (r95) of each machine, repeatability (r95) of the GC method and reproducibility (R95) of the method over a range of ethanol concentrations (1–11% V/V) was determined using commercial beers. All six instruments were linear over the ethanol range 0–12% V/V and were in good agreement. Drift of the machines was negligible over the period of the analysis. Over the ethanol range 0.95 to 6.32% V/V the repeatability (r95) and reproducibility (R95) values were 0.050 and 0.083 respectively. Over the ethanol range 9.48 to 11.15% V/V the repeatability (r95) and reproducibility (R95) values were 0.153 and 0.227 respectively. Comparison of the precision values and those obtained in a recent IOB Analysis Committee Collaborative1 for the determination of ethanol by gas chromatography showed no significant differences between the two methods. The reported method is suitable for determination of ethanol in beers.

Stopped-flow near-infrared spectrometric determination of ethanol and maltose in beers

A near-infrared spectrometric procedure has been developed for the determination of ethanol in beer samples, based on the measurement of the ethanol absorbance maximum at 1693 nm above a base-line established between 1657 and 1720 nm, employing an 1 cm pathlength cell, and using a 4.5% (w/v) aqueous solution of maltose as a reference. For the analysis of real samples the method only requires a previous degassing of the samples, by filtration, and aqueous solutions of ethanol can be employed as standards. All types of beers, from regular beers containing about 5% (v/v) ethanol to low-alcohol beers with less than 1% (v/v) can be analyzed by using the same procedure. The method has a limit of detection of 0.07% (v/v) and a relative standard deviation of 0.2% for regular beer samples, and less than 2% for low-alcohol beer analysis. The use of the stopped-flow strategy provides a fast filling and cleaning of the measurement cells and a sample frequency of 120 injections per hour. Maltose can also be determined by additional measurement at ca. 1410 nm.

Derivative Fourier transform infrared spectrometric determination of ethanol in beers

A direct derivative Fourier transform infrared (FTIR) spectrometric procedure was developed for the determination of ethanol in beer samples. The method can be applied to the analysis of all types of beers, from regular to low-alcohol beers, and only requires a previous de-gassing of the samples as a preparation step. For the analysis of regular samples, with an alcohol content higher than 1% v/v, the method involves the use of the second-derivative FTIR measurements between the baseline, established from 1055 to 1037 cm–1, and the valley at 1046 cm–1 using a micro flow cell with ZnSe windows and a spacer of 0.029 mm after the accumulation of 10 scans. For the analysis of low-alcohol beers with less than 1% v/v of ethanol, the use of the first-derivative FTIR measurements, between the peak at 1052 cm–1 and the valley at 1040 cm–1, is more convenient than the use of the second-derivative measurements. However, in this instance the measurements must be corrected, taking into account the presence of maltose, which can be quantified by measuring the height between the peak at 1160 cm–1 and the valley at 1144 cm–1 in the first-derivative spectra. In the analysis of all types of beers, aqueous solutions of ethanol can be used as standards. The limit of detection of the proposed procedure is 0.025% v/v and typical relative standard deviations of 0.8 and 1% were obtained for five independent analyses of real samples containing 5 and 1% v/v of ethanol, respectively. The aforementioned procedures were applied to the analysis of real samples and the results obtained were coincident with those obtained by a reference method.

DETERMINATION OF ETHANOL IN BEER BY GAS CHROMATOGRAPHY (DIRECT INJECTION)-COLLABORATIVE TRIAL

A method employing gas chromatography for the determination of ethanol in beer has been collaboratively tested by the Analysis Committee of the Institute of Brewing. It was judged that precision values were independent of concentration over the range 0.93 to 6.05% V/V ethanol. Repeatability (r95) and reproducibility (R95) values of 0.061 and 0.136 respectively, were obtained over this range. At a mean level of 9.17% V/V, the r95 and R95 values were 0.154 and 0.284 respectively. This was probably due to dilution errors as the sample had to be diluted to bring it within the linear range of the method. A comparison of the precision values given by the gas chromatographic method, with those obtained in 1991/1992 by 8 laboratories in a major brewing company using 12 sample pairs, for the IOB Recommended Distillation Method, revealed that there is no significant difference between the precision data for the two methods.

Direct determination of ethanol in all types of alcoholic beverages by near-infrared derivative spectrometry

A rapid and accurate method has been developed for the direct determination of ethanol in all types of alcoholic beverages. The method, which does not require any sample treatment (except for simple de-gassing for beer samples or dilution with distilled water for spirits), is based on the use of the first derivative of the near-infrared absorbance spectrum. Measurements, carried out between the 1680 nm peak and the 1703 nm valley, provide a typical calibration graph [dA/dλ= 0.00002+ 0.0127 c(where c is the concentration of ethanol in % v/v)] for a concentration range up to 25% v/v with a regression coefficient of 0.999992 and a limit of detection (for k= 3) of 0.1% v/v. The interference of sugars in the determination of ethanol can be seen by the presence of bands in the derivative spectrum in the range between 1300 and 1800 nm and can be corrected. Results comparable to those found by a reference pycnometric procedure or by gas chromatography were obtained when the proposed method was applied to the determination of ethanol in beer, white and red wines, whisky, gin and rum samples and also in sweet wines and fruit liqueurs.

Malt Beverages and Brewing Materials: Gas Chromatographic Determination of Ethanol in Beer

Abstract The American Society of Brewing Chemists collaboratively tested a gas chromatographic method for determination of ethanol in beer. Ten laboratories collaborated in a comparison of the ASBC reference method for alcohol by distillation with the GC method. The latter was shown to be at least as precise as the former, it is more rapid, and it can be used for in-line or process monitoring. The method has been adopted official first action.

Gas Chromatographic Analysis for Ethanol in Beer

This note discusses the selection and optimization of a gas chromatographic method for the determination of ethanol in beer. The reasons for the choice of separating medium and sample size are pres...