Influence of temper duration and weight distance on system output in the corn dry-milling process

Initial uniform distribution of moisture in the corn kernel is transformed into nonuniform distribution through tempering to facilitate easy fractiona tion of corn components. Proper temper duration is essential for effectiven ess of the tempering process: a short temper time is insufficient to cause necessary nonuniformity; a long temper duration may allow moisture to redis tribute uniformly. Untempered corn suffers from lack of beneficial swelling stress and therefore produces lower yields of flaking grits, coarse grits, and germ. For tempered corn, the system throughput exponentially decreases with temper duration and then stabilizes; the period of stabilization is d ependent on weight distance. Throughput values are lower at longer weight d istances. At a temper duration of 0.066 m, throughput was approximate to 33 -50% at 0.053 m weight distance. Tail stock fraction rapidly and nonlinearl y decreases with increase in temper duration; the rate of decrease is highe r at longer weight distance. The peak values of flaking grits can exceed 50 % at some combinations of weight distance and temper duration. Coarse grit yields were 9-19% and 16-24% for the shorter and longer weight distances, r espectively Germ recovery improved due to tempering, and differed only by a pproximate to0.5% at the two weight distances. Tempering lowered the oil co ntent of flaking grit, but the temper duration did not have much influence on moisture content of various fractions.