SINGLE-STAGE SHORT-DURATION TEMPERING OF CORN FOR DRY-MILLING

Pilot-scale dry-milling runs were conducted to study the feasibility o f using a short-duration single-stage tempering procedure for the temp ering-degerminating system, instead of the 17.8-21.5 hr of conventiona l three-stage tempering procedures reported in the scientific literatu re. Using a Beall degerminator No. 0, pilot-scale dry-milling experime nts were conducted at 10 tempering levels: 0, 5, 10, 15, 30, 45, 60, 1 20, 180, and 240 min. Variation in moisture content of through- and ta il-stock fractions, degerminator throughput, ratio of tail- to through -stock, yields of different sized grits from tail- and through-stock f ractions, and the recovery of germ and pericarp were used to compare t empering periods. A decrease in the milling action was observed for te mpering durations >30 min. A tempering period of 15 min gave the highe st grit recovery and a 30-min tempering period resulted in the highest germ and pericarp recovery. Based on these results, it was concluded that short tempering periods of 10-30 min as compared to 17.8-21.5 hr could be used for the tempering-degerminator system.