Milling and air classification of alkali peeled wheats
1978
Stringfellow, A.C. | Burbridge, L.H. | Pfeifer, V.F. | Brekke, O.L.
3 classes of wheat, hard red winter (HRW), soft red winter (SRW) and soft white winter (SWW), were debranned by treating 10-lb wheat samples with 10 lb 40% NaOH for 45 min at room temp. After neutralization and drying, the peeled wheat was conditioned to usual moisture levels before milling in a Buehler laboratory mill. Peeled kernels were obtained in a 92% yield for each wheat class. Final flours were lower in protein content by 0.5-1.7% and in yield by 3-10% and higher in ash by 0.2-1.3% compared with milled control samples. The least change was shown by SWW. Final flours were pin milled and air classified into 8 fractions, at cut points approx. 10, 12, 15, 18, 24, 30 and 45 μm. The 1st 3 fractions (high protein) from HRW had a combined yield of 15.5% vs. 23.4% for the control. The coarse fractions showed a corresponding increase. Each peeled wheat fraction had lower protein content than the corresponding control fraction, protein shift value was 27 vs. 42% (control), and in general properties of peeled HRW flour resembled those of hard red spring flour. Yield of the 1st 3 fractions of SRW flour was 24.6% vs. 26.8% for the control, and the protein shift was 64% vs. 60% (control). Yield of the 1st 3 fractions from peeled SWW flour was 31.7% vs. 28.8% for the control. The corresponding protein shifts were 74 and 73%. Protein and ash contents and yields for the milling and air classifying operations are tabulated.
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