Kinetic Changes of Moisture Content and Lightness of Milled Rice during Storage in Plastic Packaging

A kinetic study was carried out to assess the moisture content (MC) and lightness (L*) changes of milled rice during storage in some plastic packagings at room temperature. There were our three types of plastic packaging selected (polypropylene/PP, polyethylene/PE, polyamide/PA), as a comparison, the changes of the milled rice without packaging was also carried out. Logarithmic plot for MC and L* values produced reasonably straight lines, indicating that the increase of moisture content in milled rice kernel followed first-order kinetics to a fair approximation for all kinds of plastic bags as well as milled rice without packaging. The rate (k) of MC increases were in the range of 5?10-3 to 9?10-3 % per week. Unlike the MC, the L* values decreased during storage in plastic packaging which was noted as minus values for the rate (k) changes in the range of 7?10-3 to 1.6?10-2 per week.