Author(s):
Brányik, Tomáš 
; Silva, Daniel Pereira da ; Vicente, A. A. ; Silva, João B. Almeida e ; Teixeira, J. A.
Date: 2005
Persistent ID: http://hdl.handle.net/1822/3520
Origin: RepositóriUM - Universidade do Minho
Subject(s): Continuous; Beer fermentation; Sensorial evaluation
Description
Continuous beer fermentation offers a wide range of advantages, mostly of economic nature over
the traditional batch process. However, due to increased complexity of operation comparing to batch process,
flavor problems, risk of contamination, yeast viability, carrier price and inconvenience of immobilization, the
continuous beer fermentation has found few practical applications so far. The carrier cost represents a
significant part of the investment costs and therefore the need for a cheap support material easy to regenerate
is still relevant. This work deals with a complete continuous fermentation system for beer fermentation and
maturation consisting of an airlift and a packed-bed reactor containing brewing yeast immobilized on spent
grains and corncobs, respectively. The objective of this study was to verify the long-term performance of the
system and the suitability of these new cellulose-based carrier materials made from brewing and agricultural
by-products. Further the influence of feed rate and aeration rate on bioreactors fermentation performance,
immobilized biomass load, ethanol production and flavor profile of both green and maturated beer was
followed. The influence of process parameters on sensorial quality of beer has been studied by
physicochemical methods as well as by sensorial analysis (acceptance and description tests) carried out by
both consumers and experienced tasters. This work clearly demonstrated the technological feasibility of the
continuous brewing based on yeast immobilization on cheap alternative carriers (spent grains, corncobs) for
continuous production of a beer with a balanced flavor profile.
