A new lab scale corn dry milling protocol generating commercial sized flaking grits for quick estimation of coproduct yield and composition

Abstract

The objective was to develop a 100g lab scale dry milling protocol to determine effects of corn cultivars on coproduct fraction yields and composition. Six yellow dent, three colored and one white cultivar of corn were processed using 100g samples to generate six coproducts, namely large grits, medium grits, small grits, fines, germ and pericarp. Compositional characteristics (crude protein, crude oil and neutral detergent fiber) of corn kernel and coproduct fractions were determined and compared against commercial samples. After increasing moisture to 23.5% on wet basis, corn kernels were passed through a degerminator. Sieving and aspiration steps were used to separate endosperm, germ and pericarp fractions without using a roller mill. True sized flaking or large grits were recovered which was not possible in earlier lab scale dry milling protocol. Coproduct yields were estimated with small coefficients of variability (<10.0%). Crude oil content of large and medium grits for hard endosperm cultivars of yellow dent corn was <1.1% (db). Grits from colored corn cultivars had higher crude oil and crude protein content compared to yellow corn cultivars. Hybrid effects were responsible for variations in coproduct yield and composition. Large grits yield was correlated with absolute density (r=0.89) and test weight (r=0.85). The protocol estimated coproduct yields with low standard deviations with respect to means and yielded true sized large grits. This new 100g dry milling protocol should be helpful for industry in ascertaining dry milling characteristics of newly developed corn cultivars with small sample sizes.