Optimized production of tannase and gallic acid from fruit seeds by solid state fermentation

Purpose: To investigate the possibility for gallic acid production from different tannin-rich fruit seeds using Aspergillus oryzae via solid-state fermentation. Methods: Fruit seeds of apple, guava, tamarind, black plum and watermelon were analyzed to estimate the synthesis of an enzyme tannase and its product gallic acid. Various physicochemical parameters were optimized to increase the gallic acid yield. Gallic acid was extracted by Soxhlet apparatus and identified by Fourier-transform infrared spectroscopy (FTIR). It was quantitatively determined by high performance liquid chromatography (HPLC). Results: Amongst the various substrates tested, black plum seeds gave the highest activity of 34.40 U/g for tannase and 16.66 mg/g for gallic acid under optimized physicochemical conditions, i.e., 1:3 substrate: moisture ratio, 30 degrees C, 96 h incubation period and pH 5.5. Addition of carbon source had a negative effect on production while ammonium sulphate (0.2 %) as nitrogen source increased the yield of both products. The gallic acid produced was 98.5 % pure, compared to the standard. Conclusion: Production of tannase and gallic acid via solid-state fermentation conditions has been optimized in vitro. The optimized conditions can be utilized on a commercial scale for economically viable production of gallic acid.