Multi-enzyme Hydrolysis Of Maize Bran And Rice Straw

Ferulic acid esterase, arabinoxylanase, cellulase and Viscozyme L were used to prepare ferulic acid, oligosaccharides and monosaccharides from maize bran and rice straw. It is one of the ways to properly dispose agro by-products and make full use of these resources. The main results were as follows:Firstly, the optimal media for Aspergillus niger to produce ferulic acid esterase and arabinoxylanase used to hydrolyze de-starched maize bran and rice straw were respectively determined. The optimal medium for hydrolyzing de-starched maize bran was: wheat bran: maize bran: bagasse: water = 2: 1: 1: 8 added with 4% of (NH₄)₂SO₄ and 2.33% of MgSO₄ (on the basis of dry matter) respectively. The optimal medium for hydrolyzing rice straw was: rice straw: wawter =1:2 added with 4% of (NH₄)₂SO₄ and 2.33% of MgSO₄ (on the basis of dry matter) respectively. The enzymes were obtained by extracting with 7 times (5 times for 1st amd 2 times for the 2nd extraction) of water.Secondly, the optimal technology for hydrolyzing de-strached maize bran and rice straw by multi-enzymes were determined. When hydrolyzing de-strached maize bran (substrate), highest degree of hydrolysis was obtained when 16% of substrate was suspended in the enzymes from Aspergillus niger mixed with 5% of cellulase and Viscozyme L (on the basis of substrate) respectively and reacted at pH5.5, 45^C for 24 h. While for rice straw, highest degree of hydrolysis was obtained when 8% of substrate was suspended in the enzymes from Aspergillus niger mixed with 10% of cellulase(on the basis of substrate) and reacted at pH4.5, 45℃for 12h.Thirdly, 5 kinds of pretreatments of rice straw to enhance enzymic hydrolysis were investigated. The results showed that four pretreatment methods, including high-temperature combined with high pressure, ultrasonic, diluted acid and alkali treatments significantly increased enzymic release of ferulic acid, oligosaccharides and monosachharides but fermentation pretreatment did not.Fourthly, the released ferulic acid and sugars were analysed by HPLC and ion chromatogram. The results of HPLC showed that the phenolic acid prepared from maize bran and rice straw was mainly ferulic acid. The results of IC showed that the component of sugars prepared from maize were glucose (49.13%), xylose (27.82%) and arabinose (16.22%); and the component of sugars prepared from rice straw were glucose (63.48%), xylose (14.34%) and arabinose (5.85%). The results also showed that monosaccharides were the main components in maize bran hydrolysates while oligosaccharides were the main components in the hydrolysates of rice straw.