Dry Milling and Extrusion of Proso Millet and the Role of Millet Lipids on Extrudate Sensory Properties
Structurally, millet is a small grain, composed of an outer fibrous pericarp, a starchy endosperm and a germ body. The traditional milling method of millet is labor intensive, time consuming, and yields a poor endosperm fraction. Modern millet dry milling is a technique that has been used on a limited basis, but is not well understood. The purpose of this study, using abrasive dry milling, was to establish a laboratory process flow that will enhance baseline research and advance the commercial milling of millet. A commercial short flow abrasive dry milling system was developed for the production of low fat and fiber millet grits. The process is defined in two major steps; abrasive decortification and endosperm grit aspiration. The endosperm grit produced averaged a yield of 83.5 % with fat and fiber levels of 1.9 % and .61 %. In addition, this research was designed to focus on millet lipids and their role in off flavor formation in single screw extrudates. The design was created to compare refined millet and corn oil addition at increasing levels in a corn meal control to understand if millet lipids cause a higher rate of oxidation leading to off flavors and odors in extruded extrudates. This is important to understand if millet usage is to be increased using single screw extrusion to make snack foods and cereals. In this research, analysis by lipid chemistry, human sensory and direct ionization it was found that millet lipid addition to a base corn meal formula did not create abnormal concentrations of off flavors and odors in extrudates.