State of the art in immobilized/encapsulated cell technology in fermentation processes

Abstract

Immobilized yeast cells are being used in various bio-industries but also could be beneficially implemented in industries based on ethanol fermentation. For reasons including faster fermentation rates in comparison to traditional processes, increased volumetric productivity, and the possibility of continuous operation, immobilized yeast technology has attracted increasing attention in these industries over the last 30 years. Nowadays, immobilized yeast technology is well established in a number of processes, such as sparkling wine production, secondary beer fermentation, and alcohol-free and low-alcohol beer production. However, some processes like wine fermentation, cider fermentation, and primary beer fermentation are still under scrutiny in the lab or at pilot-scale levels. These processes are significantly more complex and have various side reactions that are important in flavor formation and final product quality. At the moment, the major challenge facing the successful application of immobilized cell technology (ICT) on an industrial scale is yeast physiology control and fine-tuning of flavor formation during fermentation processes. In this review, the process requirements, carrier materials, and bioreactor design for fermentation with immobilized cells are discussed. In addition, the influence of ICT on the formation of flavor-active compounds (i.e., higher alcohols, esters, and vicinal diketones) is described.