Electrostatic generation of alginate microbeads loaded with brewing yeast

Abstract

The substantial concern with the possible use of immobilized yeast cells for beer production is reduction of internal mass transfer resistance during continuous fermentation. One way to minimise this problem is to use small-diameter beads. The effects of bead diameters in the range 0.3-2.0 mm on yeast cell immobilization and growth over a short-term cultivation were investigated. Bead diameters in the range 0.5-0.6 mm were optimal and provided rapid cell growth and the highest final cell concentration (2.33 x 10(9) cells/ml of beads). Electrostatic droplet generation was investigated as a technique for production of alginate microbeads. The effects of applied potential, internal needle diameter and electrode position on bead diameter were assessed. The results have shown that this method can be used for controlled production of small-size microbeads loaded with yeast. Depending on applied conditions it was possible to produce the beads in the range 250 mum-2.0 mm in diameter.