This paper presents an application of fuzzy logic control to isomerized hop
pellet production. The hop is very important in the brewing industries bec
ause a hop of high quality provides a good aroma to the beer and gives cons
istency to the foam. The iso-merited pellets in this case study, are produc
ed by warming stabilized pellets to approximately 50 degrees C and holding
them for one-two weeks. The alpha acids are almost completely isomerized un
der these conditions. The fuzzy controller was shown to have a high degree
of robustness producing good results such that the quality of the product i
s guaranteed. A comparison with other control approaches widely used in the
industry is performed using a nonlinear computer model. (C) 1999 Elsevier
Science Ltd. All rights reserved.