AN EXPERT-SYSTEM APPLIED TO THE PHYSIOLOGICAL ANALYSIS OF EARLY-STAGEOF BEER FERMENTATION

A fuzzy expert system was applied to the knowledge analysis of yeast p hysiology in the early stage of beer fermentation, when the wort was a erated. We used ergosterol and glycogen concentration in the wort as a suitable marker of physiological state of the cell population. The am ount of both compounds influences the rate of fermentation, cell growt h and the final taste of beer. The concentrations of ergosterol and gl ycogen including the number of cells can not be measured immediately d uring the relatively short aeration period, and incomplete experimenta l data are therefore found in laboratory logbooks. We therefore sugges ted that the fuzzy relation between the directly measurable dissolved oxygen concentration and the rate of ergosterol or glycogen formation should be identified and a fuzzy expert system should be used to analy ze the behavior of the yeast.