VIEW ARTICLE    DOI: 10.1094/ASBCJ-53-0039

Applications for an Electronic Aroma Detector in the Analysis of Beer and Raw Materials (1). Timothy P. Bailey and Roger V. Hammond, BRF International, Nutfield, Surrey, England RH1 4HY, and Krishna C. Persaud, Department of Instrumentation and Analytical Science, University of Manchester Institute of Science and Technology, Manchester, England M60 1QD. (1) Based on a presentation at the American Society of Brewing Chemists Annual Meeting, Tucson, AZ, June 1993. J. Am. Soc. Brew. Chem. 53(1):39-42, 1995. Accepted August 3, 1994.

A prototype electronic aroma detector (Odourmapper) has been developed by the University of Manchester Institute of Science and Technology and is undergoing trials at BRF International. The trials are being conducted to determine its ability to differentiate between beers and to recognize the presence of important beer aromas and varietal/quality parameters of malt and hops. Purified air displaces the headspace above a sample, which passes over an array of conducting polymers mounted on an electronic chip. The change in conductivity of the sensors at the interface with molecules present in the vapor flow is measured as a voltage. The responses from these polymers are rapid and reversible at room temperature. The change of resistance of each polymer is displayed in real time on a personal computer, which stores data. The software includes a neural network pattern recognition program with which, after appropriate training, differentiation between control beers and beers spiked with hydrogen sulfide, dimethyl sulfide, or diacetyl has been achieved. There is promise for some hop varietal differentiation. Further development will be required to utilize these findings for commercial use, but there are many potential uses for quality assurance. Keywords: Beer aroma, Conducting polymers, Diacetyl, Dimethyl sulfide, Electronic aroma detector, Hops, Hop varietal differentiation, Hydrogen sulfide, Neural network, Sensory analysis