VIEW ARTICLE    DOI: 10.1094/ASBCJ-41-0068

A New, Dissolved-Oxygen Analyzer for In-Line Analysis of Beer. R. Mitchell and J. Hobson, Samuel Webster's Brewery, Ovenden Wood, Halifax, England; N. Turner, Orbisphere UK Ltd., Staveley Hall, Staveley, Chesterfield, Derbyshire S43 3TW; and J. Hale, Orbisphere Laboratories, 1222 Vesenaz, Geneva, Switzerland. J. Am. Soc. Brew. Chem. 41:0068, 1983.

Experiments are described that prove the suitability of an Orbisphere membrane-enclosed dissolved-oxygen sensor for in-line use in a brewery. Also, a selection was made of the optimum membrane material and thickness for wort-and beer-monitoring tasks. Determinations are reported for four membranes of the usual parameters, such as the range of linear response to oxygen concentration, the sample flow requirement, and the speed of response to oxygen-concentration changes at various temperatures between 0 and 30° C. Resistance of the sensor to various physical and chemical conditions commonly encountered in a brewery was also investigated. The steady-state sensitivity of the sensor was unaffected by applied pressure in the range to 20 bars, and a simulated "hot-cleaning" operation at 90° C caused a temporary small increase of + 3% in sensitivity which, after 2 hr, decayed to + 1%. Extensive tests also showed that the specific sensitivity of the sensor towards oxygen was not influenced by the simultaneous presence of carbon dioxide, in both gaseous and beer samples. A preliminary report is given of 12 months of in-line experience with the sensor for oxygen monitoring at various points in a brewery.

Keywords: Dissolved oxygen analysis, Feedback control of dissolved oxygen, Oxygen probe