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Wet-milling Characteristics of Propionate-treated High-moisture Maize I.

Cereal Chem. 69(1):43-46.
Wang, C. and L.A. Johnson. 1992.

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 propionic acid (99% pure, pH 1.7), a mixture of sodium propionate and sodium acetate (as might be recovered from fermentation) 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 maize was forced-air dried (25°C) to 12% moisture and used as an untreated control. Treated maize was stored at 25°C for six months before wet milling. When the grain was treated with propionate, yields of germ were lower and contained less protein and more oil compared with untreated air-dried maize because of increased leaching of protein from germ during steeping. Starch yields increased because of propionate treatment, but residual protein levels in the recovered starch were unacceptably high. Gluten yields and purities of propionate- treated high-moisture maize were lower than those of untreated air-dried maize.