| Wheat bran was rich in dietary fiber, especially content of natural phenolic antioxidantferulic acid was high, and so it was becoming more and more attention. The wheat bran yieldwas higher in our country (annual output about24million ton), but its deep processing andutilization extensions were rather lower and waste resources seriously, which was mainly usedto produce animal feed. Therefore, its comprehensive utilization was increasingly active.Moreover, ferulic acid already attracted extensive attention because it was thought to bebeneficial to human health by exerting functional activity such as free radical scavenging,antisepsis and antiphlogosis, decreasing blood lipids, and antithrombotic, so it was possesseda good development and application prospect. However, the low water solubility, instabilityand easily oxidized of ferulic acid seriously affect efficacy exertion of its bioactivity.Therefore, this research subject used wheat bran as the raw material to prepare ferulic acid,and from the chemistry structure of ferulic acid, increased the glucosyl base in order to raisestability and solubility. Moreover, the vitro antioxidant activity between pretherapy and poststructure modification were compared in order to enlarge its application range. So thatprovided theoretical basis for comprehensive development and utilization of wheat bran. Inthis subject, the main results were as follows:The extraction rate of ferulic acid was taken as the index for investigation; the optimumconditions for extract ferulic acid from wheat barn by ultrasonic-assisted xylanase methodwere studied. The optimum technological parameters were obtained by orthogonal test asfollowing: solute weight to solvent ratio1:10(g/mL), ultrasonic power150W, ultrasonic time20min, enzymolysis temperature50℃, enzymolysis time45min, enzymy addition level1.2%,enzymolysis pH5.0, under these conditions,94.48%of extraction rate of ferulic acid in rawmaterials were reached.The crude products of ferulic acid were purified by column chromatography with ethanolas eluent. The results showed that the HPD100macro porous resin had the best separatingefficiency under the following conditions: In the adsorption process, ferulic acid concentrationin the work solution was330mg/mL, pH was5.0, and the adsorption velocity was1.5mL/min;and in the desorption process, the elution agent was50%ethanol, the elution flow rate was0.5mL/min. Under these conditions, thin layer chromatography (TLC) was used foridentifying purity of ferulic acid, the result showed the sample was well separated, and the purity of ferulic acid was93.7%.In this reaserch, the purified samples of ferulic acid modified with glucose were studied.The conversion ratio of ferulic acid as main index for investigation, the influences of solventscategory, reaction time, reaction temperature, enzyme concentration, acid-sugar molar ratio,substrate concentration and pH were discussed in detail, respectively. The optimization ofreaction condition was obtained. The results showed the best suitable solvent was methylethylketone in this reaction system, the reaction time was32h, the reaction temperature was65℃,the enzyme concentration was20%, the molar ratio of acid to sugar was1:1, the substrateconcentration was0.1mol/L and the reaction pH was7.0. Under these conditions, theconversion ratio of ferulic acid reached30.82%. Novozym435had a high stability; theconversion ratio of ferulic acid could still reached14.15%after it was used continuously sixtimes.By comparing the vitro antioxidant activity of ferulic acid and glucose ferulic acid esters,they were effective anti-oxidants. But the antioxidant activity of glucose ferulic acid esterswas better than ferulic acid. Meanwhile, the results of preliminary antimicrobial activity testshowed that ferulic acid and glucose ferulic acid esters had a certain inhibitory effect onEscherichia coli, Bacillus subtilis, Staphylococcus aureus and yeast. |
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