Yeast immobilisation for brewery fermentation

Cell immobilisation is the physical restriction of cells in a delimited region by means of physical and chemical approaches. It usually comprises a solid support containing cell biomass. In brewing fermentations, yeast cell immobilisation was widely explored during the 1970s to the 90s, with the expectation that immobilised systems would revolutionise the brewing industry. The most studied immobilisation method has been the attachment to a surface and entrapment within a porous solid. Some industrial applications were developed, but the flavour profile of the product rarely matched that produced by batch fermentation. Numerous factors are important in immobilised yeast systems and its successful industrial implementation. Although cell immobilisation results in many advantages, such as high biomass loading and ease of cell reuse, there are drawbacks including physiological changes and mass transfer limitations. Therefore, in order to design a feasible brewing fermentation process using immobilised yeast cells, the solid support, immobilisation method and the bioreactor system require to be properly developed. In this review, yeast cell immobilisation technology in brewing is considered together with methods of immobilisation with the associated advantages and drawbacks. Physiological and metabolic alterations in yeast are also explored and industrial applications are highlighted. It is suggested that immobilisation technology has new opportunities as the market is increasingly open to novel flavours and styles. (c) 2021 The Institute of Brewing \& Distilling (AU)