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Dilute sulfuric acid pretreatment of corn stover was used to obtain a solution of high concentration of xylose from the hemicellulosic fraction and a relatively low concentration of glucose, which not only saved the hemicellulase but also made a full use of corn stover. Then the study considered the selectivity (xylose-glucose ratio) as an important parameter to optimize the hydrolysis conditions. The results optimized by response surface methodology (RSM) showed that the optimum conditions for pretreatment were found to be H2SO4 concentration of 2.4% and reaction time of 100min at 100°C. Under these conditions, 78.8% of xylose yield was achieved and the glucose yield was lower than 11.6%. To confirm these results, the optimum condition was performed and the actual results of xylose yield and glucose yield were 78% and 11.3%.

Ferulic acid, a compound showing antioxidant ability, is found in abundance in wheat bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans, ligin, cellulose and so on. Response surface methodology and orthogonal design were respectively used to evaluate the effects of NaOH concentration, alkali/ethanol ratio, extraction temperature and pH on ferulic acid extraction yield from wheat bran. The released ferulic acid concentration was determinated by HPLC method Experiments carried out under the predicted optimal conditions，with NaOH concentration of 5.76%, pH of 3.2, alkali/ethanol ratio of 1.39:1, temperature of 59.75 °C, the actual extraction yield in agreement with the expected yield, with 4.45mg.g-1 extraction rate of ferulic acid in wheat bran . And the results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme.

ABSTRACT:The effects of drying method on the sugar conversion of corn stover during dilute sulfuric acid pretreatment were studied. oven-dried corn stover (oDCS) was more sensitive to temperature and time during dilute sulfuric acid pretreatment than air-dried corn stover (aDCS). The yield of the total reducing sugar reached 43.9% when oDCS was pretreated for 50 min at 120°C, which was even higher than the value of the aDCS treated for 90 min. The glucose yield of oDCS was 1.6-to 1.9-fold higher than aDCS. These results indicate that rapidly losing water is a better drying method compared to air drying.