Micronization of maize flour: Process optimization and product quality.

Micronization refers to high temperature short time processing of grains using near infrared rays. The
present study is focused on optimization of process conditions for micronization of maize flour with an
emphasis on enhancing rapidly digestible starch (RDS) content for enhancing starch digestibility and
inactivation of peroxidase enzyme for probable extension of shelf-life. The study employed a central
composite design (CCD) with three variables namely, time (60e180 s), temperature (130e170 �C) and
moisture content (20e40%) with RDS and peroxidase contents as responses. The optimized micronization
conditions (173 s, 159 �C, 40% mc; 164 s, 166 �C and 40% mc) resulted in 7.1e7.7% increase in RDS
content and 92.5e96.2% inactivation of peroxidase enzyme, respectively, without significantly affecting
protein, carbohydrate and fat content of flour. Validation studies showed that experimental values
matched well with that of predicted, suggesting suitability of the model used. At the optimized conditions,
micronization was also able to inactivate lipase activity by 66.9e68.2%.