Cereal Chem 69:47-49   |  VIEW ARTICLE

Wet-Milling Characteristics of Propionate-Treated High-Moisture Maize. II. Qualities of Starch and Gluten.

C. Wang and L. A. Johnson. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

High-moisture (25.6%) maize was treated with three forms of 1.0% propionate (weight treatments adjusted to obtain equivalent moles of propionate ion). These were propinoic acid (99% pure, pH 1.7), a mixture of sodium propionate and sodium acetate acidified with HCl to the pKa of propionic acid (pH 4.8), and the same mixture of sodium propionate and sodium acetate acidified to the natural pH of propionic acid (pH 1.7). Another sample of the maize was forced-air dried (25% C) to 12% moisture content. Propionate- treated and untreated maize samples were stored at 25 C for six months before wet milling. Starch recovered from propionate-treated maize contained greater amounts of residual protein than did starch from untreated air-dried maize and was more yellow in color. Starch from propionate-treated maize had lower pasting viscosities than did starch from untreated air-dried maize, indicating partial hydrolysis. No differences in the thermal properties of the starches were observed. Gluten from propionate-treated maize contained lower concentrat ions of protein and was less yellow than gluten from untreated air-dried maize. Addition of a small amount of sodium chloride to the mill-starch slurry improved starch-gluten separation in propionate-treated maize.