OPTIMUM POPPING MOISTURE-CONTENT FOR POPCORN KERNELS OF DIFFERENT SIZES

A single variety of commercial yellow popcorn was separated into five size-fractions by screening with round-hole sieves of 4.36, 4.76, 5.16 , 5.56, and 5.95 mm. Each of the five fractions and the control sample were conditioned to seven moisture content levels ranging from 11 to 14%. The conditioned samples were popped in a Cretor metric weight vol ume tester. The relationship between expansion volume and moisture con tent for each size-fraction and the control sample was described by a quadratic equation. The optimum moisture content for popcorn retained on the round-hole sieves at 5.95, 5.56, 5.16, 4.76, and 4.36 mm was de termined to be 13.18, 12.91, 12.85, 13.58, and 13.47%, respectively. W hen the moisture content varies from the optimum value by +/- 1%, the expansion volume could be reduced by as much as 2%. It was proposed th at kernels need only to be separated into two size classes using a 5.1 6-mm round hole sieve: 1) the suggested moisture content for kernels p assing through the sieve would be 13.5%;2) the suggested moisture cont ent for kernels remaining on the sieve would be 13%.