Enzymatic synthesis of gallic acid esters using microencapsulated tannase: effect of organic solvents and enzyme specificity

Enzymatic synthesis of gallic acid esters from gallic acid and alcohols in organic solvents was studied using microencapsulated tannase from Aspergillus niger. Microencapsulated tannase showed higher synthetic activity than free enzyme. The water content of the system can significantly affect the equilibrium shift. In water–hexane system, the equilibrium-controlled reaction was favorable to synthesis of propyl gallate with increase of organic solvent content. The effects of various organic solvents (log P: −1.3 to 6.6) on the enzymatic reactions were investigated and the highest yield was 44.3% in benzene (log P: 2.0). Enzyme specificity for the alcohol portion (C1–C18) of the ester showed that the most suitable substrate was 1-propanol.