Influence of micronization on physicochemical properties of maize grains.

Micronization of maize varieties viz. Nityashree (NAH-2049) and Arjun (EH-434042) was carried
out in a near-infrared (NIR) based system. Infrared (IR) processing conditions such as moisture
content and time of exposure were standardized to inactivate peroxidase and lipase enzymes and,
to improve starch digestibility. Micronization of maize at 200°C for 4 min resulted in 16–20%
increase in rapidly digestible starch (RDS) content. The process was effective in completely
inactivating peroxidase enzyme and reducing lipase activity by 83–86%. The process did not
induce any marked changes in total carbohydrates and protein contents. Reduction in pasting
viscosities, peak viscosity (PV), and set back viscosity (SV) of micronized maize flour indicated
partial gelatinization of starch. Micronized Arjun flour exhibited higher RDS content, which was
correlated with lower viscosity profile values compared to Nityashree flour. Inactivation of
enzymes in micronized maize provides the scope for shelf-life extension of flour. Improvement
in RDS content increased water absorption capacity, and low viscosity profile provides an
opportunity for its inclusion in preparing calorie dense foods having high solids concentration.