Maize milling

by Emily Wilson
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I was glad to read the article by Tony Evers, "Maize considered a versatile performer on the world stage," (see World Grain, September 2000, page 18). I am interested in dry milling of maize.

Our college succeeded in establishing one semi-dry maize mill plant in Tangshan, China, with a capacity of 220 tonnes per day of corn. A part of the floury endosperm (about 55%) can be converted to 1% germ oil and edible alcohol; the horny endosperm can be converted to pearl rice (grits).

I have a few questions for Mr. Evers about the floury endosperm. Would it be produced by fermentation of glucose? Can maize be dry milled with a traditional wheat flour mill line? How does one realize the whole procedure?

Jian Qin

Zhengshou Grain College,

Zhengshou, China

Editor's reply: Mr. Evers writes, "Glucose production is most frequently carried out by use of enzymes extracted from microorganisms. The starch is first gelatinized in the presence of thermostable alpha amylases, resulting in the production of dextrins. Subsequently, the filtered and decolorized digest is incubated with the enzyme glucoamylase to produce glucose. The fructose molecule is sweeter than glucose so conversion of some dextrose (glucose) to fructose is achieved by treatment with the enzyme isomerase.

"Milling of maize by conventional wheat milling machinery is possible but optimal results are achieved if the embryo and bran are removed before size reduction is attempted. Specialized equipment and flows are also beneficial in reducing particle size and purifying endosperm to give the required fractions. Information from machinery manufacturers should be beneficial here.

"To realize the whole procedure on a commercial scale will require consultation with a manufacturer of appropriate plant, or collaboration with an existing producer in China or another country."