Beer and Beverage analysis

Flavor stability is a primary attribute of beer, beer mixed drinks, as well as other (non-) alcoholic beverages. Flavor changes are attributed to oxidative reactions that are promoted by radicals and suppressed by sample constituents with antioxidant properties. The EPR technique is accepted as being a highly effective and powerful tool to monitor oxidative stability.

MS-5000 EPR spectrometer for beer and beverage safety and quality control

  • EPR, using spin trapping reagents, is feasible to detect free radicals in beer and beverages.

  • The MiniScope MS-5000 benchtop ESR spectrometer is a compact and easy-to-use device, ideal for quality assurance in breweries and beverage producing industries.

  • The MiniScope MS-5000 helps to determine key parameters such as the Endogenous Antioxidative Potential (EAP/Lag-Time).

  • Equipped with an auto-sampler, the MiniScope MS-5000 enables effective handling of large sample amounts with minimal operator handling.

  • MiniScope MS-5000 comes along with the EPRStudio software, offering a user friendly platform for result calculation and documentation.

Beer Analysis Technique

Fig. 1: ESR measurement of beer, EAP after SO2 addition of 0,2,4,6 mg/L
Fig.2: BAX evaluation by linear fit of EAP values (BAX = slope)

The determination of the Endogenous Antioxidative Potential (EAP) and the Beverage Antioxidative index (BAX) using Electron Spin Resonance measurements (ESR) is an ideal tool for the evaluation of the beer’s oxidative flavor stability and shelf time. The bench-top ESR Spectrometer MS 5000 along with the novel Autosampler unit allows a fully automated measurement of these values.

Facts:

  • Fully automated handling of samples

  • Up to 30 samples per analysis

  • Temperature control up to 70°C

  • Automatic EAP and BAX calculation

  • State-of-the-art and user friendly software

 

Beer Analysis Technique:

Due to the chain reaction of beer-derived free radicals, carbonyl end products like aldehydes and ketones are created, which cause the staling of beer. However, the endogenous antioxidants inhibit the free radical oxidation until they are depleted. Hence this free radical oxidation can be minimized by optimizing brewery operations and storage conditions to provide a maximum antioxidant content on the packaged beer. At each stage of the brewing process the comprehensive antioxidant status of the beer/beverage can be detected by ESR measurements and the determination of the EAP- and BAX value. That way, the shelf life and flavor stability of a finished beer can be determined at the individual stages of the brewing process e.g. before packaging and distribution.

 

ESR EAP and BAX evaluation:

The EAP measurement is based on the indirect detection of the radical generation in beer during accelerated beer ageing at a raised temperature (60 °C). The thereby  formed short-lived reactive radicals can be monitored by trapping them with spin trap reagents (POBN) and detecting the stable spin trap adducts by using the MS 5000 Bench-Top ESR spectrometer. For a certain period of time the radical generation is delayed or prevented by the beer’s endogenous anti-oxidative activity (lag-phase). After the lag phase the amount of spin adducts begins to increase rapidly. The EAP value is a measure for the duration of the lag phase, hence a beer with a high EAP value has a long flavor stability and vice versa. Figure 1 demonstrates such an EAP determination of beer after the addition of different amounts of SO2. The novel EAP value is linear dependent of the SO2 content (fig. 2) and offers a new beneficial index number for the evaluation of the flavor stability; the so called Beverage Antioxidative index (BAX). The BAX provides additional information about the anti- and pro-oxidative properties of the beer matrix regardless of the SO2 content and gives information of the consumption rate of the existing antioxidative potential during storage.
With the MS 5000, its autosampler unit and the comprehensive software both values (EAP and BAX) can be measured fully automated and with high precision.

 

 


References

  • ASBC Methods of Analysis - Beer-46: Measurement of Oxidative Resistance in Beer by Electron Paramagnetic Resonance

  • MEBAK: Bd. “Würze, Bier, Biermischgetränke” (2012)  2.15.3 Endogenes Antioxidatives Potential (EAP-Wert) und Radikalgenerierung (T-Wert) von Getränken (ESR-Spektroskopie)

  • R. J. Elias, M. L. Mogens, L. Andersen, L. H. Skibsted, A. L. Waterhouse: Identification of Free Radical Intermediates in Oxidized Wine Using Electron Paramagnetic Resonance Spin Trapping; Journal of Agriculture and Food Chemistry Vol. 57, pp. 4359-4365 (2009)

  • M. Uchida, S. Suga; M. Ono: Improvement for Oxidative Flavor Stability of Beer-Rapid Prediction Method for Beer Flavor Stability by Electron Spin Resonance Spectroscopy; Journal of the American Society of Brewing Chemists, Vol. 54, no. 4, pp. 205-211 (1996)

  • H. Kaneda, Y. Kano, T. Osawa, N. Ramarathman, S. Kawakishi, K. Kamada: Detection of Free Radicals in Beer Oxidation; Journal of Food Science, Vol. 53, no. 3, pp. 885-888 (1988)