Continuous Beer Fermentation Using Immobilized Yeast Cell Bioreactor Systems

Abstract

Traditional beer fermentation and maturation processes use open fermentation and lager tanks. Although these vessels had previously been considered indispensable, during the past decades they were in many breweries replaced by large production units (cylindroconical tanks). These have proved to be successful, both providing operating advantages and ensuring the quality of the final beer. Another promising contemporary technology, namely, continuous beer fermentation using immobilized brewing yeast, by contrast, has found only a limited number of industrial applications. Continuous fermentation systems based on immobilized cell technology, albeit initially successful, were condemned to failure for several reasons. These include engineering problems (excess biomass and problems with CO(2) removal, optimization of operating conditions, clogging and channeling of the reactor), unbalanced beer flavor (altered cell physiology, cell aging), and unrealized cost advantages (carrier price, complex and unstable operation). However, recent development in reactor design and understanding of immobilized cell physiology, together with application of novel carrier materials, could provide a new stimulus to both research and application of this promising technology.

Characteristics of High Cell Density Fermentations with Different Lager Yeast Strains

“…One main problem of most of the accelerated fermentation systems remains diacetyl, because of the higher production of its precursor α-acetolactate and the incomplete chemical conversion of α-acetolactate to diacetyl, causing incomplete removal of diacetyl by yeast, due to the short residence times 7 . However, several strategies can be followed to decrease the diacetyl content in beer, such as accelerated maturation using immobilised yeast 27 , supplementation of α-acetolactate decarboxylase to the wort 19 or the use of genetically manipulated yeast strains 20,32 .…”

Physicochemical Characterization of the Yeast Cells and Lignocellulosic Waste Used in Cell Immobilization for Ethanol Production

“…Cells were harvested by centrifugation at 6000 g and 4°C for 10 min and washed with increasing concentrations of ethanol in water (10,20, and 50% v/v). The resulting pellet was resuspended in 50% (v/v) ethanol.…”

“…The removal was performed with a solution of NaOH 0.1% by mechanical agitation at 150 rpm for 24 hours at room temperature. The drying was performed at 105°C by 12 hours [20].…”

Yeast: World’s Finest Chef

“…Enhancing beer and wine flavour through modification of by-products formation is another field of intensive research [30,39]. As it is the improvement of the fermentation process, through encapsulation/immobilization of yeast [48].…”