ARS | Publication request: Crude protein, ash, phosphorus, neutral detergent fiber and starch concentrations in particle size distributions of corn steam flaked to varying bulk densities

Submitted to: Proceeding of Plains Nutrition Council Symposium
Publication Type: Abstract Only
Publication Acceptance Date: March 25, 2009
Publication Date: April 9, 2009
Citation: Hales, K.E., Cole, N.A., Leytem, A.B., Galyean, M.L. 2009. Crude protein, ash, phosphorus, neutral detergent fiber and starch concentrations in particle size distributions of corn steam flaked to varying bulk densities [abstract]. 2009 Plains Nutrition Council Spring Conference, April 9-10, 2009, San Antonio, Texas. Texas AgriLife Research & Extension Pub. No. AREC 09-18. p. 94.

Technical Abstract: The particle size distribution that results from steam flaking cereal grains could be related to differences in the chemical composition of steam-flaked (SF) vs. unprocessed grain. Particle size distribution and associated crude protein (CP), phosphorus (P), neutral detergent fiber (NDF), and starch concentrations in corn steam flaked to bulk densities of 22, 26 or 30 pounds/bushel was evaluated by tempering whole shelled corn to13% moisture (wt/vol) for approximately 18 h, steam conditioning for 20 m, followed by flaking to the desired densities. Resulting SF corn was sieved to determine the proportions in particle size categories of > 8,000 micro-u, 4,760 to 8,000 micro-u, 2,360 to 4,760 micro-u, 1,180 to 2,360 micro-u, 600 to 1,180 micro-u, and < 600 micro-u. Concentrations of CP, P, NDF, and starch were analyzed in the particle size fractions and in the whole flakes. Data were analyzed as a completely randomized design with batch (5 to 6 batches per bulk density) as the experimental unit using the Mixed procedure of SAS. There was an interaction (P < 0.01) between sieve size and bulk density for the proportions of chemical components within each sieve size. The proportion of starch, CP, ash, and NDF in particles collected on the largest sieve (>8,000 micro-u) decreased (P < 0.05) as bulk density decreased. In addition, the proportion of total starch within particles of 4,760 to 8,000 µm was greater (P < 0.05) for 22 and 26 than for 30 pound/bushel flakes. For total CP, the proportion collected on the 1,180 and 4,760 micro-u screens was greater (P < 0.05) for 22 than for 30 pound/bushel flakes. The proportion of P in particles greater than 4,760 micro-u in size decreased (P < 0.05) with more extensive grain processing, whereas it was greater (P < 0.05) for 22 than 26 and 30 pound/bushel flakes in the particles smaller than 1,180 micro-u. The proportions of total NDF and ash in the 1,180 µum size particles increased (P < 0.05) with decreasing bulk density. Concentrations of starch, CP, ash, P, and NDF in the whole flakes were not affected by bulk density. The greatest proportion of corn grain particles were in the 8,000 micro-u screen, whereas the 600 µm sieve had the least particles. Therefore, within the range of bulk density we evaluated nutrients are not lost during steam flaking; however, these nutrients may accumulate in finer particles created during the steam flaking process. If smaller particles are disproportionately sampled, flaked corn could seem to differ in composition from the intact grain.