Publication no. C-2001-0411-02R |  VIEW ARTICLE

Influence of Temper Duration and Weight Distance on System Output in the Corn Dry-Milling Process.

S. K. Mehra (1) and S. R. Eckhoff (2). (1) Former doctoral student, Department of Agricultural Engineering, University of Illinois, Urbana, IL 61801. Presently with Cargill Foods, Dayton, OH. (2) Professor, Department of Agricultural Engineering, Univ. of Illinois, Urbana, IL 61801. Corresponding author. E-mail: <seckhoff@uiuc.edu> Cereal Chem. 78(3):222-225. Accepted November 30, 2000. Copyright 2001 American Association of Cereal Chemists, Inc.

Initial uniform distribution of moisture in the corn kernel is trans­formed into nonuniform distribution through tempering to facilitate easy fractionation of corn components. Proper temper duration is essential for effectiveness of the tempering process: a short temper time is insufficient to cause necessary nonuniformity; a long temper duration may allow mois­ture to redistribute 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 dependent on weight distance. Throughput values are lower at longer weight distances. At a temper duration of 0.066 m, throughput was approximately 33-50% at 0.053 m weight distance. Tail stock fraction rapidly and nonlinearly decreases with increase in temper duration; the rate of decrease is higher 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, respectively. Germ recovery improved due to tempering, and differed only by approximately 0.5% at the two weight distances. Tempering lowered the oil content of flaking grit, but the temper duration did not have much influence on moisture content of various fractions.