Kernel Moisture Content Variation in Equilibrated Rice Samples

An individual kernel moisture meter and an individual kernel oven drying procedure were used to quantify the kernel-to-kernel moisture content (MC) variation in equilibrated rough rice samples varying in MC from 9 to 37%, w.b. Average, bulk sample MCs were also determined using an oven drying method. No difference (p < 0.05) was found in the average MCs measured by the meter at three weeks or three months from the time the samples were conditioned. The average MCs measured by the meter and the individual kernel oven procedure were in close agreement with those determined by the bulk sample oven method. A characteristic response in the standard deviation of the individual kernel MCs measured by the meter was observed for both storage periods. The standard deviation increased exponentially from approximately 0.5% at 10% average MC to 4.5% at 26% MC. The coefficient of variation also increased dramatically with average MC, indicating that the hygroscopic response to MC change of individual rice kernels within a sample is different.