Preparation Of Phenolic Acids From Corn Bran And Cobs By Membrane Separation Technology

In this research, ferulic acid, feruloylated oligosaccharides from corn bran, andcoumaric acid from corn cobs were prepared using membrane separation technology. Themain results were as follows:1. Membrane separation technology for ferulic acid from corn branFerulic acid was released from corn bran by alkaline-ethanol aqueous solution, thussignificantly decreased the viscosity of the extracts and makes it easy for furtherpurification by membrane separation. The optimal extraction technology was: one weightof corn bran was suspended in10volume of extraction solution (0.25mol/L NaOHdissolved in50%ethanol solution) and extracted at75C for2h under constant stirring at120rpm. Ferulic acid in the extracts was concentrated and purified using ultrafiltrationand nanofiltration successively.86.4%of ferulic acid was recovered in the permeats whenthe extracts were ultrafiltrated using the membrane with5kDa molecular cutoff and0.6m2available membrane area. The permeats after ultrafiltration was then nanofiltratedusing a membrane with150Da molecular cutoff and0.25m2available membrane area;when the concentration factor reached4.3,94.3%of ferulic acid was maintained in theretentate; the pH value of which was then adjusted to2.0and the crystal of ferulic acidwas obtained. After the extraction and separation processes, it yielded16.5g/kg of ferulicacid powder with the purity of55.8%.2. Membrane separation technology for coumaric acid from corn cobsCoumaric acid was released from corn cobs by alkaline hydrolysis, and then separatedand purified by ultrafiltration and nanofiltration successively.84.3%of coumaric acid wasrecovered in the permeats when the extracts were ultrafiltrated using the membrane with5kDa molecular cutoff and0.6m2available membrane area. The permeats afterultrafiltration was then nanofiltrated using a membrane with500Da molecular cutoff and0.25m2available membrane area and87.8%of coumaric acid was recovered in thepermeats; the permeates continue to be nanofiltrated using a membrane with150 Damolecular cutoff and0.25m2available membrane area, when the concentration factorreached2.0,76.3%of coumaric acid was maintained in the retentate; in which, the pHvalue was adjusted to2.0and the crystal of coumaric acid was obtained. After theextraction and separation processes, it yielded10.4g/kg of coumaric acid powder with thepurity of86.4%.3. Membrane separation technology for feruloylated oligosaccharides from corn branUltrafiltration (membrane with5kDa molecular cutoff and0.6m2available membranearea) and nanofiltration (membrane with150Da molecular cutoff and0.25m2availablemembrane area) were applied to separate and purify the feruloylated oligosaccharidesreleased from corn bran by oxalic acid autoclaving process. It was found that91.8%ofreleased feruloylated oligosaccharides were recovered in the ultrafiltration permeats, and95.3%of feruloylated oligosaccharides were maintained in the nanofiltration retentate.After the extraction and separation processes, it yielded159.2g/kg of feruloylatedoligosaccharides powder; in which, the contents of total ferulic acid, reducing sugars, totalsugars were3.2%,77.3%,86.2%, respectively.