Preparation Of Ferulic Acid And Oligosaccharides From Maize Bran By Ferulic Acid Esterase And Arabinoxylanase

The liquid and solid mixture enzymes containing ferulic acid esterase and arabinoxylanase were prepared by ultrafiltration and lyophilization, respectively, and the enzymes were used to hydrolyze the destarched maize bran (DSMB) to release ferulic acid and xylo-oligosaccharide.Hollow fiber membrane with molecular cutoff weight of 20,000 was applied to concentrate mixture of ferulic acid esterase and arabioxylanase. The optimal parameters of ultrafiltration were: inlet pressure of 0.10～0.15MPa, temperature of 25~30℃, and pH value of 8.06. Under these conditions, the enzymes were concentrated more than six times, thus more convenient for preservation and transportation. Moreover, if the concentrates were diluted by 10 times and ultrafiltrated once more, 90% of oligosaccharides and ferulic acid could be removed and the substrate inhibition was avoided.A solid mixture of ferulic acid esterase and arabinoxylanase was prepared by freeze-drying using a lyophilizer. The results showed that the enzymes were not denatured during the freezing process, but partial activities were lost in drying process. In the lyophilization process, the optimal thickness of fermented broth was 6～7 mm and the most efficient agent for maintaining the activity of enzymes was PEG. When 1%～2% of PEG were added to fermented broth, more than 95% of total activity for arabinoxylanase and nearly 100% of total activity for ferulic acid esterase were recovered after freeze-drying. The preservation test showed that both liquid and solid enzymes were quite stable during storage at 4℃.Releasing of ferulic acid and xylo-oligosaccharides from DSMB by mixture enzymes was also investigated. The optimal parameters for enzymic hydrolysis of DSMB were 100ml of enzyme solution (pH=4.4) which contained 8g DSMB and reacted at 40℃. Under the optimal condition, 23.5% of ferulic acid and 18.4% of reducing sugars were released by enzymic hydrolysis for 24 hours. Meanwhile, the effect of thermal and high-pressure pretreatment of DSMB for enzymic hydrolysis was researched. It...