Simultaneous control of apparent extract and volatile compounds concentrations in low-malt beer fermentation.
Volatile compounds cause undesirable flavor when their concentrations exceed threshold values in beer fermentation. The objective of this study is to develop a system for controlling apparent extract concentration, which indicates the fermentation degree and which should be decreased below a targeted value at a fixed time under a constraint of tolerable amounts of volatile compounds. In beer fermentation, even though the production of volatile compounds is suppressed by maintaining a low fermentation temperature, a low temperature causes a delay in the control of apparent extract concentration. Volatile compound concentration was estimated on-line, and the simulation of apparent extract consumption and volatile compound production was performed. To formulate various beer tastes and conserve energy for attemperation, optimal temperature profiles were determined using a genetic algorithm (GA). The developed feedback control of the brewing temperature profile was successfully applied, and apparent extract and volatile compound concentrations at a fixed time reached their target concentrations. Additionally, the control technique developed in this study enables us to brew a wide variety of beers with different tastes.
Kobayashi
Michiko
M
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, 565-0871 Osaka, Japan.
Nagahisa
Keisuke
K
Shimizu
Hiroshi
H
Shioya
Suteaki
S
D000143:Acids / Q000032:analysis*; D000438:Alcohols / Q000032:analysis*; D001515:Beer / Q000032:analysis* / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism; D002523:Edible Grain / Q000737:chemistry; D005285:Fermentation; D008954:Models, Biological; D012440:Saccharomyces / Q000378:metabolism; D013649:Taste; D013696:Temperature; D014835:Volatilization
D000143:Acids; D000438:Alcohols; D002245:Carbon Dioxide