Jm. Membre et Jl. Tholozan, MODELING GROWTH AND OFF-FLAVORS PRODUCTION OF SPOILED BEER BACTERIA, PECTINATUS-FRISINGENSIS, Journal of Applied Bacteriology, 77(4), 1994, pp. 456-460
The genus Pectinatus includes strictly anaerobic Gram-negative non-spo
re-forming mesophilic bacteria often referred to as beer-spoilage bact
eria. Pectinatus frisingensis was chosen as the reference strain. The
organisms were grown in batch cultures under stringent anaerobic condi
tions in a synthetic medium and with pH regulation. Various glucose an
d lactate concentrations were used, and a low inoculum reproduced spoi
lage conditions in bottled beer. Propionate and acetate are the major
compounds responsible for the off-flavour of beer. Gompertz curves wer
e fitted to acid-biomass production and glucose consumption; thereby t
he lag-phase, production rate and final concentrations were derived. V
olatile fatty acids production began 19 h after biomass growth. There
was no linear effect of substrate on final concentration of propionate
, acetate and biomass. An additive model is proposed for the predictio
n of bacterial growth and acid production on both glucose and lactate.