Synthesis of propyl gallate from tannic acid catalyzed by tannase from Aspergillus oryzae: Process optimization of transesterification in anhydrous media

Improving the catalytic capability of enzyme is an important challenge of biocatalysis in organic medium. Optimization of organic reaction system and reaction mode can elevate the catalytic ability. In order to enhance the catalytic efficiency of tannase-catalyzed transesterification from tannic acid, process parameters of the reaction and reaction mode were optimized further to improve the conversion rate of substrate. The result showed that with hexane as solvent, a conversion rate of substrate, 75%, was achieved at 40 °C in 20 mL reaction mixture composed of 0.75% water and 7.5% n-propanol, and that semicontinuous catalysis was the most favorable for production of propyl gallate, its average production rate was 2.5-fold that of batch catalysis. By SCC, a noted computative conversion rate of approximate, 90%, was obtained. Thus, it is expected that this study may present an efficient and ecofriendly method for industrial production of PG.