Production of high-content galacto-oligosaccharides mixture using β-galactosidase and Kluyveromyces marxianus entrapped in polyvinylalcohol gel

The production of a high-content galacto-oligosaccharides mixture (GOS) by immobilised beta-galactosidase and yeasts in LentiKats (R) lens-shaped polyvinylalcohol (PVA) capsules was evaluated. Galacto-oligosaccharides were produced from lactose (300 g L-1) by immobilised fungal beta-galactosidase and the yeast Kluyveromyces marxianus in polyvinylalcohol hydrogel in batch mode. The low-content GOS mixture produced by the immobilised enzyme consisted of 71.7 g L-1 with a final purity of 22.7 % after 30 h of transgalactosylation reaction at 30 degrees C and pH 4.5. The low-content GOS mixtures were subsequently used in 20 repeated batch runs with immobilised yeasts for increasing the GOS content. Digestible sugars were fermented to ethanol and the resulting mixture consisted of 88 mass % of GOS after 26 h of fermentation. The PVA lenses exhibited high fermentative stability without any mechanical deformations. (C) 2016 Institute of Chemistry, Slovak Academy of Sciences