Determination Of Ethanol In Beverages Research Articles

Semi-Automated Enzymatic Determination of Ethanol in Beverages: Collaborative Study for RIDA®CUBE Ethanol

Easy and quick methods to quantify ethanol reliably in beverages are always important. In 2022, the EnzytecTM Liquid Ethanol test kit was approved as AOAC Official MethodSM 2017.07 Final Action after a collaborative study was conducted with different beverages such as kombucha, juices, and beer. During set-up of this collaborative test, small sized companies asked to include the RIDA®CUBE Ethanol/RIDA®CUBE SCAN device since it is easy to use, suitable for a few samples only and contains the identical reagents as the EnzytecTM Liquid system. It is applicable to quantify ethanol in diluted kombucha, fruit juices, and alcohol-free beer samples around 0.5% alcohol-by-volume within 12 min. The overall relative reproducibility standard deviation across a wide concentration range for kombucha, was calculated to be 6.29%. Analysis of juices and beer showed an overall higher variation with an estimated overall RSD(R) value by regression of 14.4%. The data obtained by this collaborative study show that the RIDA®CUBE Ethanol in combination with the RIDA®CUBE SCAN device is suitable to quantify ethanol from matrices representing important alcohol-free liquid food categories.

Amperometric biosensors based on alcohol oxidase and peroxidase-like nanozymes for ethanol determination.

The aim of the current research is to design alcohol oxidase-based amperometric biosensors (ABSs) using hybrid metallic nanoparticles as artificial peroxidases (PO) or PO-like nanozymes (NZs). A lot of metallic PO-like NZs were synthesized and tested with respect totheir ability to substitute natural PO in solution and on amperometric electrode. The most effective PO mimetics were coupled with alcohol oxidase (AOX) on graphite electrodes (GEs) and characterized. Two types of modified GEs, namely, the AOX/nAuCePt/GE and the AOX/nFePtAu/GE show the highest sensitivities to ethanol (2600 A⋅M-1⋅m-2 and 1250 A⋅M-1⋅m-2, respectively), low limits of detection (1.5µM and 2.2µM), broad linear ranges (5 - 100µM and 12 - 120µM), as well as satisfactory storage stabilities. The most sensitive bioelectrode AOX/nAuCePt/GE was used as ABS for ethanol determination in real samples. The practical feasibility of the constructed ABS was demonstrated by determination ofethanol in beverages, human blood and saliva.

A Novel Amperometric Biosensor Based on Poly(allylamine hydrochloride) for Determination of Ethanol in Beverages.

Herein, we report on a new type of ethanol biosensor based on a screen-printed electrode modified with poly(allylamine hydrochloride). The alcohol dehydrogenase was immobilized on the surface of the sensor using the sol–gel matrix. Working parameters such as applied potential, pH, NAD+ concentration, storage conditions were optimized. A response range between 0.05 and 2 mM was found with a sensitivity of 13.45 ± 0.67 µA/mM·cm2 and a detection limit of 20 µM. The developed biosensor was used to detect ethanol in commercial beverages with good accuracy.

An Automated Single Interface Flow System for the Spectrophotometric Determination of Ethanol in Beverages Based on Schlieren Effect

A new and expeditious automated procedure for the determination of ethanol content in alcoholic beverages (distilled liquors and wine) by using a single interface flow analysis (SIFA) system with spectrophotometric detection is presented. The developed approach was simply based on refractive index gradient measurements, known as Schlieren effect, produced when acidified beverages samples were introduced in a single-line SIFA system that used deionized water as carrier (trailing) stream and a computer-controlled spectrophotometer as detector. In the implemented SIFA system, no chromogenic reagent is used, being the refractive index gradient a consequence of the mutual interdispersion of sample and carrier zones at the formed single interface, and no predefined volumes of both sample and carrier are required, which greatly simplifies system operation and optimization. The proposed methodology allowed the determination of ethanol concentrations between 4% and 24% (v/v) with good precision (RSD < 5.2%, n = 3) and a sampling frequency of about 58 h−1 with consumption of 400 μl of sulfuric acid 0.5 mol l−1 and 400 μl of sample per measurement. The developed procedure was applied to whisky, gin, rum, vodka, the sugar cane-based beverage “cachaca,” and white wine, and the obtained results were in a good agreement with those provided by the reference method (RD < 5.0%). Recovery values acquired in the analysis of spiked ethanol samples (between 90.0% and 111.0% of the added amount) were also satisfactory.

Determination of ethanol in beverages by flow injection, pervaporation and density measurements

A fast, clean and easy to automate flow injection-pervaporation method for the determination of ethanol in different beverages using density measurements is proposed. The method is based on separation of the ethanol from the sample using a pervaporation module; the analyte being collected in water as acceptor liquid. The density of this water–alcohol mixture is measured at the detector. After optimisation by either a univariate or multivariate approach as required, a linear range between 0 and 40% was established. Then, the assessment of the method versus a reference one was studied in terms of repeatability (0.12% v/v), reproducibility (0.32% v/v), detection limit (0.11% v/v) and traceability. The sample throughput was 15 samples h −1. The method was in agreement with the reference methods used in the European Union.

Amperometric determination of ethanol in beverages at copper electrodes in alkaline medium

Abstract The anodic oxidation of ethanol at copper surfaces in alkaline medium has been reported. The participation of electrogenerated Cu(III) species in the electrocatalysis of the oxidation of ethanol at copper surfaces was investigated by rotating ring-disc voltammetry and a mechanism involving the participation of radicals was proposed. The copper oxide sensor was assembled in a wall-jet electrochemical cell and a FIA method that incorporates flow extraction of ethanol through a PTFE membrane at room temperature was developed. Under optimal experimental conditions the peak current response (measured at 0.5 V versus Ag/AgCl) increases linearly with ethanol concentration over the range 2–10% (v/v). The repeatability of the electrode response in the FIA configuration was evaluated as 3% ( n =20) and the limit of detection of the method was 0.4% ( S / N =3). The analytical frequency was estimated to be 120 h −1 . Experiments to investigate the selective of the PTFE membrane were carried out and they demonstrated that only small molecules such as methanol may interfere in the determination of ethanol. For some samples of different alcoholic beverages, the results showed excellent agreement ( r =0.998) with the ones obtained by using gas chromatography.

Extraction and Gas Chromatographic Determination of Ethanol in Beverages

Extraction and Gas Chromatographic Determination of Ethanol in Beverages

Spectrophotometric method for the determination of ethanol in beverages and beer samples using cerium (IV) as reagent

A simple and rapid (15min) spectrophotometric method for the determination of subpercentage ethanol in beverages is based on the colour reaction between ethanol and Ce(IV). Other alcohols and reducing substances interfere, but may be minimized by distilling the alkali and mercuric chloride treated sample. Calibration was linear up to 0.78% v/v, with r.s.d. of 5.0% at the ethanol level of 0.34% v/v. the ethanol contents of a number of non‐alcoholic beverages and beer samples were determined and compared with results from AOAC and gas chromatographic methods.

Derivative Fourier transform infrared spectrometric determination of ethanol in alcoholic beverages

A derivative Fourier transform infrared (FT-TR) spectrometric procedure was developed for the direct determination of ethanol in alcoholic beverages, from beers to spirit samples. The method is based on first-order derivative FT-IR measurements between the peak at 1052 cm −1 and the valley at 1040 cm −1, which are present in aqueous solutions and alcoholic beverages, by using a micro flow transmittance cell with ZnSe windows and a spacer of 0.029 mm. The method involves the accumulation of ten scans and provides accurate results in the determination of ethanol in alcoholic beverages without requiring any previous chemical treatment of the sample or a previous separation or extraction step. The limit of detection corresponds to 0.025% (v/v) and results obtained in the analysis of real samples of beer, wine, vodka, gin and whisky agree with those found by different reference procedures. For the determination of ethanol in beverages containing high concentrations of sugars, it is necessary previously to determine the sugar content by measuring the derivative value between 1164 and 1147 cm −1 and subsequently to correct the negative interference of sugars on the determination of ethanol between 1052 and 1040 cm −1.

Flow-injection determination of ethanol by fiber-optic chemiluminescence measurement

A new approach for the determination of ethanol in beverages is presented. The hydrogen peroxide generated in the enzymatically catalyzed oxidation of ethanol is measured by the luminol chemiluminescence reaction using potassium hexacyanoferrate(III) as a catalyst. Alcohol oxidase is immobilized on aminopropyl glass beads packed in a glass column. The chemiluminescence measurement is made using an optical fiber to transport the luminescence from the flow cell to the detector in conjunction with a flow system. This assay system responds linearly in the ethanol concentration range 3 × 10 −6-7.5 × 10 −4 M with a precision of 2.4% and an analysis time of 1.5 min.

Gas-diffusion dilution flow-injection method for the determination of ethanol in beverages without sample pretreatment

The combination of immobilized alcohol oxidase (AOD) with a gas-diffusion membrane in a flow-injection system greatly enhanced the specificity of ethanol determination. This gas-diffusion flow-injection system with amperometric detection of hydrogen peroxide had a linear range of analysis from 0.0006 up to 60% (v/v) ethanol. Silicone-modified polypropylene membranes of different thickness were used. Undiluted samples of beer, wine, spirits and medicine could be investigated with excellent correlation with standard methods ( r > 0.997). The frequency of analysis was 120–180 samples h −1 and the operational half-life of the immobilized enzyme was 8000 injections within 44 h.