OPTIMIZATION OF SOLID-STATE MIXED FUNGAL FERMENTATION OF TOTAL PHENOLIC COMPOUNDS FROM DEFATTED RICEBERRY BRAN USING SUBCRITICAL WATER EXTRACTION

Abstract

The aim of this study was to optimize the proportion of mixed culture fungi: Aspergillus oryzae, Aspergillus awamori and Monascus purpureus for enhancing the total phenolic compounds from defatted Riceburry bran (DRB) via solid-state fermentation (SSF) and employing Response Surface Methodology (RSM) with modified Box Behnken Design. In addition, fermented DRB was extracted the bioactive compounds by using subcritical water extraction at 200°C for 30 minutes. In all experiments, the fungal growth was almost uniform through the DRB at a room temperature for 5 days, 55% moisture content, pH 5.5 and 6 x 10⁷ spores/g DRB. The optimum of SSF conditions for mixed cultures of fungi as A. oryzae and M. purpureus was the proportion of 0.07 to 0.93. A. awamori has no significant influent on enhancing active compounds with mixed cultures of fungi. The prediction values of total phenolic content obtained 20.22 mg gallic acid equivalent / g dry DRB, which increased 1.7 times of non-fermented DRB. Thus, the model fitted almost seamlessly to the experimental data.