关键词: 玉米皮渣, 酸降解, 响应面法, 蒸汽爆破处理, 还原糖

Abstract:

In order to increase reducing sugar yield from corn bran as a by-product of the production of corn starch by
wet milling, the optimal conditions for preparation of reducing sugar from corn bran by steam explosion combined with
acid hydrolysis were investigated in this research. First of all, the one-factor-at-a-time method was employed to examine
the effects of sulphuric acid concentration, hydrolysis time, temperature and material-to-liquid ratio on reducing sugar
content. Subsequently, the optimization of process parameters for improved reducing sugar content was performed using
Box-Behnken design and response surface methodology. Hydrolysates were analyzed by ion chromatography. The results
showed that the maximum reducing sugar content of 54.61% was obtained under the following optimal conditions: sulphuric
acid concentration, 1.66%; hydrolysis time, 1.5 h; temperature, 120 ℃; and material-to-liquid ratio, 1:10 (g/mL), which
was increased by 9.58% as compared to that obtained without steam explosion pretreatment. Ion chromatography analysis
indicated that the hydrolysate obtained was mainly composed of D-glucose (19.34 mg/mL), D-xylose (16.01 mg/mL)
and L-arabinose (10.37 mg/mL). In comparison to the raw material, the fiber structure of the residue left after the preparation of
reducing sugar was more loose and more significantly cracked, showing more holes and cracks on its surface, revealing that the
cellulose, hemicellulose and lignin in corn bran can be well decomposed by successive steam explosion and acid hydrolysis. This
result is in accordance with the reducing sugar content in the degradation solution obtained after both treatments.

Key words: corn bran, acid hydrolysis, response surface methodology, steam explosion, reducing sugar