2009 Annual Report
Dry milling of grain sorghum is a small, but expanding segment of the milling industry. Limited publications exist on sorghum milling techniques, and processes developed for individual sorghum milling operations remain proprietary. However, as research regarding sorghum utilization continues to expand, milling techniques will be developed that take advantage of the unique characteristics of the sorghum kernel.
The objective of any flour milling operation is twofold: the first is to reduce the kernel into finer particles; the second is to achieve an efficient separation of the kernel entities. More specifically, it is desirable to produce the cleanest possible separation of endosperm, germ, and bran, while recovering a maximum yield of endosperm. Depending on the objective, either clean endosperm grits or flour are the desired end-products. For flour production—the focus of this review—there are two general approaches to milling. The first involves the removal of the germ and the kernel’s outer layers (including pericarp, seed coat, aleurone, and nucellus—referred to as “bran”), collectively called “degermination.” This step is followed by subsequent reduction of the remaining endosperm. This method is utilized in maize milling. Alternatively, the kernel can first be broken open, allowing the endosperm to be scraped from the bran layer. This method is primarily utilized for wheat and rye milling. With either method, the endosperm fraction should have as little bran and germ contamination as possible, as these products discolor the flour and affect the shelf-life of the product. Additionally, for both methods, a product composed of overlapping kernel fractions is obtained, designated as “shorts” or “fines.” Included in this fraction are portions of all milling streams, which due to composition, color, or most importantly, particle size, cannot be combined into the flour or bran fractions. To do so would sacrifice product quality.
The report herein is focused on the processing and utilization of sorghum and sorghum products in food applications not yet prevalent in the North American market. These areas include sorghum flour production, treatment, and batter bread and gluten free beer.
Activities of this project are monitored by frequent personal meetings, emails and phone calls, as well as through shared graduate students between the ADODR and PI.