Factors Affecting Dissolved Oxygen Analyses in Beer and Water. Charles W. Hahn and Jerome C. Hill, Adolph Coors Company, Golden, CO 80401. J. Am. Soc. Brew. Chem. 38:0053, 1980.

The responses of the primary instrumental methods of dissolved oxygen (DO) analysis-polarographic probe and galvanic cell analyzers-to the influences of beer carbonation level, pH, and temperature were investigated. Temperature change in the measured fluid had a significant effect on meter response but could be compensated for in the polarographic analyzer by proper calibration techniques. Beer carbonation level changes produced DO deviations in the galvanic cell as high as 3 µg/kg per 0.10 increase in carbonation level. In the second phase of testing, responses of the various analyzers were compared with the absolute DO values determined by theoretical calculations from gas/liquid equilibria. At a constant temperature, all analyzers performed satisfactorily in measuring incremental changes in DO in water and beer. However, deviations were shown in the absolute level of DO depending upon the method of calibration: the indigo carmine method produced significantly higher levels than those obtained by instrumental calibration of air or other methods highly specific for oxygen. A possible reason for this deviation is the existence of irregularly occurring electron transfer agents.

Keywords: Dissolved oxygen, Dissolved oxygen calibration methods, Gas/liquid equilibrium absolute DO values, Instrumental analysis