Drying characteristics of grain corn subjected to different drying techniques

Abstract

Grain corn is one of the most important crops for feed production in Malaysia. Freshly harvested grain corn contains a significant amount of moisture content ranging from 25% to 30% (wet basis), which must be reduced to a safe level through the drying process for storage stability. In view of this, whole grain corn was subjected to various drying techniques to evaluate the drying performance and its quality retention. Grain corn was harvested at an optimum maturity of 110 days after planting and dried in ambient, sun and oven at 40°C. Ambient drying of whole grain corn showed the longest drying time, followed by sun drying and oven drying at 40°C. The time taken to reduce moisture content to less than 12% (wet basis) was observed to be 359 hrs for air-dried samples, 292 hrs for sun-dried samples and 55.5 hrs for oven-dried samples. Mathematical modelling for each drying technique demonstrated that Midili’s equation displayed the best fitting to describe the drying characteristics of air-dried samples of grain corn, while the diffusion approach’s equation was the best mathematical model for sun and oven-dried samples. The concentrations of total carotenoids in the final products for all drying treatments were in the range between 0.290 mg/g to 0.346 mg/g for all drying techniques indicating better stability with low deterioration rates when subjected to low temperature drying.