Enzymatic hydrolysis of micronized corn flour at low temperatures

In order to develop a new technology for enzymatic hydrolysis of corn flour at low temperatures, two-step enzymatic hydrolysis was performed for commercial corn flour(with median particle size of 273.6 μm) and micronized corn flour(with median particle size of 17.1 μm), and the effects of liquefaction temperature on the liquefaction rate and glucose yield were studied at the temperature range of 30～70℃. Experimental results showed that the relationship between the liquefaction rate and the liquefaction temperature could be expressed by an Arrhenius equation at the temperature range of 40～70℃ for commercial corn flour and at the range of 30～70℃ for micronized corn flour. The activation energy of liquefaction for commercial corn flour was 4.63×10⁴ J/mol. It was decreased to 2.15×10⁴ J/mol for micronized corn flour. At 40℃, the liquefaction rate of micronized corn flour was 2.5 times higher than that of commercial corn flour. In the enzymatic hydrolysis of micronized corn flour, the effect of liquefaction temperature on glucose yield was not significant. A glucose yield of 95.4% was obtained for micronized corn flour, which was considerably higher than 79.2% for commercial corn flour. It was found that liquefaction temperature could be decreased, and liquefaction rate and glucose yield could be increased by the micronizing of corn flour.