Wheat middlings

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Wheat middlings (also known as millfeed, wheat mill run, or wheat midds) is the middle of three grades into which flour and meal are classified: patents, middlings, and clears. Middlings are often used in animal feed.[1]

The term is somewhat imprecise, as it does not take into account the various mill streams and proportions that are combined and ultimately constitute the product's final composition. As a consequence of this inconsistent terminology, difficulties are encountered when ascertaining nutritional value and establishing economic worth. Wheat midds are sometimes referred to negatively as 'floor sweepings' although such products are generally captured long before they would end up on the floor.

From a human nutrition standpoint, it is notable that wheat milling methods to produce white flour eliminate those portions of the wheat kernel (bran, germ, shorts, and red dog mill streams) that are richest in proteins, vitamins, lipids and minerals. For example, highly refined patent flour may contain only 10 to 12% of the total thiamine and niacin, 20% of the phosphorus, and 50% of the calcium of the parent grain [2]

Durum semolina is a kind of wheat middlings made from durum wheat; it is used to produce pasta, breakfast cereals, puddings, and couscous.

When used in feed for livestock or horses, middlings can be a good source of protein, fiber, and phosphorus, along with various other nutrients. However, flour milling products arising from a fairly homogeneous parent grain can vary greatly depending upon the objectives of the milling process. Thus, the degree of nutrient variation in wheat midds can be a major consideration in determining whether its inclusion in a ration or formula feed is beneficial.[3] It has 96 percent of the energy value of barley and 91 percent of the energy value of corn.[4] It is also used frequently as an inexpensive filler for pet food for animals such as dogs and cats, who do not digest wheat products as readily.[5]

Due to its high energy content and low price, wheat middlings is being researched as a biofuel.[6] A burner designed to make good use of it is the USDA-OARDC AFBC, a small scale Atmospheric Fluidized Bed Combustor.[7] This technology originated in the 1920s in the chemical industry and was adopted by the power sector in the 1980s. Dr. Harold Keener has led the research on the OARDC-AFBC for the past twenty years, though the project lost some funding after the resolution of the energy crisis associated with the 1990 oil price shock.[8]

Nutrient Value[4]
Analysis Percentage

Dry Matter 89%
Crude Protein 16.5%
Crude Fiber 7.5%
Neutral Detergent Fiber 32%

Sources

  1. Cook's Illustrated, January 1981, p. 55, as quoted in the Oxford English Dictionary s.v. middling 2b
  2. Shellenberger, J. A. 1970. Nutritional values of wheat and wheat by-products as affected by modern production and milling techniques. Proc. Intern. Symp. “Wheat in Livestock and Poultry Feeds.” June 18–19, Okla. State Univ. p. 34–41.
  3. Wheat Middlings Composition, Feeding Value, and Storage Guidelines
  4. 4.0 4.1 Ingredients101
  5. Best Grain Free Dog Foods
  6. Ohio State University
  7. FryMulti.com
  8. Case Study Technology & Innovation – Atmospheric Fluidised Bed Combustion Technology in the United States