Preparation of baicalein from baicalin using a baicalin-β-D-glucuronidase from Aspergillus niger b.48 strain

•Baicalin-β-d-glucuronidase from Aspergillus niger b.48 strain was purified.•Purified enzyme, M.W., 45 kDa; optimal temperature, 50 °C; optimal pH, 5.0.•Pure enzyme hydrolyzed baicalin to baicalein, did not hydrolyze glycyrrhizin.•1% baicalin was reacted at pH 5.0 and 50 °C for 24 h into baicalein by crude enzyme.•10.7 g baicalein was obtained from 20 g baicalin, molar yield, 88.4 %.