A novel and efficient immobilised tannase coated by the layer-by-layer technique in the hydrolysis of gallotannins and ellagitannins

• Tannase can be immobilised on eupergit and protected by LbL-coating without loss in activity.
• LbL-coated immobilised tannase retains its depsidase and esterase activities.
• LbL-coated tannase retains up to 50% of its activity after 7 days of continues use.
• LbL-coated tannase is still active on both gallotannins and ellagitannins.
• Reactions can be followed conveniently by a recently developed 31P NMR-based method.

Tannase (EC 3.1.1.20) was quantitatively immobilised onto Eupergit® C 250 L and coated by layers of alternatively charged polystyrene sulfonate and polyallylamine hydrochloride, respectively. The layer-by-layer (LbL)-coated immobilised tannase, i.e., LbL-tannase retained its original activity and showed significant resistance to deactivation and maintained 50% of its activity after seven consecutive cycles of hydrolysis reactions, each run for 24 h. The LbL coating did not hinder the substrate access to the active site of the enzyme. Both gallo- and ellagitannins were efficiently hydrolysed upon treatment with LbL-tannase. The formation of gallic acid and the reaction patterns were followed by HPLC and the recently developed 31P NMR analytical method for the characterisation of tannins.