Beer brewing with immobilized yeast cells - Current experiance and recent results

Abstract

Immobilization of yeast cells offers many potential advantages in beer brewing and during the recent years, it has gained increasing interest in brewing industry. Over free cell systems, such as higher cell densities and loads, it enables much higher fermentation rates and remarkable shortening of the brewing process. This paper outlines several favourable bioreactor designs for primary beer fermentation and results obtained in internal loop gas-lift bioreactor system, introduced in this field by our research group. Several extrusion techniques for cell immobilization were investigated for production of alginate beads. Application of extrusion under gravity force, extrusion under coaxial air-jet and electrostatic droplet generation resulted in beads with diameters which ranged from 0.3 to 2 mm. These beads were successfully used in repeated batch and continuous beer fermentation in an internal loop gas-lift bioreactor for up to 3 months. Alginate was shown to be a suitable carrier for yeast cells. During a period of 3 months immobilized yeast cells have shown unchangeable activity and viability. Fermentation time was reduced below 1 day and final beers had desired sensory and analytical profiles.