Noël Girardet, Buhler, Uzwil, Switzerland; F. H. Webster, Francis Webster & Associates, Branson, Missouri, U.S.A.
OATS: Chemistry and Technology, Second Edition
Pages 301-319
DOI: https://doi.org/10.1094/9781891127649.014
ISBN: 978-1-891127-64-9
Abstract
Grain milling has been practiced since the beginnings of civilization. The earliest milling processes were extremely primitive. The first attempts by humans to mill grain ultimately led to the development of the mortar and pestle. The grain was crushed between two rocks, one of which had a large, flat surface with a slight indentation; the other (pounding stone) was oval, with a rounded bottom and a top that fit easily into the hand. The next major advance in milling was the burr mill, in which the grain was ground between a stationary circular, flat stone and a similar but rotating stone positioned directly above it. The distance between the stones determined the flour granulation. Milling technology remained rather primitive until the latter part of the nineteenth century. As the technology developed, iron or porcelain rolls gradually replaced the stone mills. These advances, coupled with changes in power options, led to more efficient mills that produced more-refined and better-quality flours and meals.
Oats are one of several grains that provide a unique challenge to millers. The traditional oat kernel, as harvested, is encased in a hull that consists of an outer and inner layer botanically known, respectively, as the lemma and the palea (see Chapter 5). These hulls must be removed before the grain is processed into finished products. Fortunately, the hull and kernel are not fused together, as is the case for barley and rice, and thus may be removed with minimal disruption of the kernel tissue. The first major improvement to oat milling was a dehuller that was patented in 1840 by a U.S. miller. The next major advance occurred in 1875 when Ferdinand Schumacher of the United States patented a cutting machine. It allowed the oats to be cut into three or four pieces with minimal production of fines. The resulting steel-cut oats rapidly replaced the coarse meal produced by burr mills as the preferred product for oat porridge. Although steel-cut oats took longer to cook, they had a significantly longer shelf life. At that time, processed oats were stored in open barrels and were subject to the development of rancidity. The crushed meal, due to the larger surface area, was much more likely to develop oxidative rancidity.
The capability of cutting oats, coupled with the development of roller mills, provided the basic technology needed to produce rolled oats as we know them today. Subsequently, steam was added to the process to serve as a binder and reduce the amount of fines produced during rolling. The steaming partially precooked the flakes and was the first step in the development of “instantized” products. The first “instantized” ready-to-cook product was marketed in 1877, using the “3 minute” symbol (Thorton 1933).
Oat milling has undergone several refinements since those early days. This chapter describes the various steps involved in modern oat storage, handling, and processing. Additionally, specifications for milling-quality oats are discussed in detail.
