Mechanochemical effects of micronization on enzymatic hydrolysis of corn flour

Corn flour samples with different particle size were prepared by ball milling, and then liquefaction and saccharification of the corn flour samples were carried out by using commercially available α-amylase and glucoamylase, respectively. Mechanochemical effects of micronization on the enzymatic hydrolysis were studied for developing a new technology of low-temperature enzymatic hydrolysis of corn flour.The commercial corn flour of 273.6 μm could be micronized to 17.5, 15.4, 14.6, 13.3 and 9.8 μm in median diameter by wet-milling for 20 min, 1, 2, 3 and 5 h, respectively. Microscopic observation and X-ray diffractometry revealed the starch crystal structure of corn flour could be destroyed by wet-milling for more than 3 h. All the wet-milled corn flours could be liquefied at 30 °C. The liquefaction rate of corn flour increased with increasing wet-milling time. The glucose yield was 46.8% for the 20 min milled corn flour. It was increased to 83.7% by wet-milling for more than 3 h. The increase of glucose yield corresponded with the destruction of starch crystal structure and the decrease of gelatinization temperature.Our experimental results indicated that wet-milling had mechanochemical effects, which resulted in a remarkable increase of glucose yield in low-temperature enzymatic hydrolysis of corn flour.