VIEW ARTICLE DOI: 10.1094/ASBCJ-39-0147
Factors Affecting Dissolved Oxygen Analysis in Beer and Water. T. J. Wisk, J. T. Weiner, and K. J. Siebert, The Stroh Brewery Co., Detroit, MI 48226. J. Am. Soc. Brew. Chem. 39:0147, 1981.
A number of chemical and instrumental dissolved oxygen techniques were studied for their response to added oxygen as well as to factors other than oxygen (pressure, flow, SO2, Cl2, and pH). Polarographic (IL 531, IL 540, IL 545) and galvanic (Hays meter) instruments showed similar increases in output with added oxygen (in beer), but the galvanic instrument gave different absolute values. The difference in absolute values was largely caused by the indigo carmine calibration technique (used to calibrate Hays meters), which responds to species other than dissolved oxygen. Pressure and flow rate had little effect on polarographic instruments, provided the oxygen concentration was below saturation. The Hays meter output decreased with decreasing flow rate. Decreasing the pH of water by the addition of phosphoric acid lowered the apparent oxygen content as assessed by the Winkler and IL 531 methods, whereas the Hays method showed an increase. Chlorine in water caused an apparent oxygen increase with the Hays meter and a decrease with the IL 531 analyzer. Sulfur dioxide in water produced an apparent oxygen increase with the IL 531 analyzer. Calibration of the Hays meter near the low end of its range produced low oxygen results. When an "offset" was introduced in the calibration procedure, the performance of the Hays meter improved. A single offset value was not useful with all Hays meters, as each instrument examined had a somewhat different response to oxygen.
Keywords: Beer, Calibration, Dissolved oxygen, Nonoxygen effects, Water