2012 Annual Report
1a.Objectives (from AD-416):
The overall goal of this project is to improve the quality of high soluble fiber oat cultivars. Specific objectives for the project period: Optimize methodologies for the extraction and analysis of soluble oat fiber components; determine environmental variation in the quantity and quality of ß-glucan as characterized in the first objective in newly developed high ß-glucan cultivars and other oat cultivars; and determine relationships between oil concentration and ß-glucan concentration in segregating crosses for these traits, as to how each affects groat breakage during dehulling.
1b.Approach (from AD-416):
Health benefits derived in humans from the consumption of oats are currently understood to be related to the molecular weight of the soluble fiber component commonly called beta-glucan and the increased viscosity of the gut contents created by high molecular weight beta-glucan. We will develop optimized methodologies for the extraction of beta-glucan in order to evaluate its physical and structural, molecular weight, and viscometric properties. We will collect oats samples, including those from newly developed high soluble fiber cultivars, from replicated plots grown in diverse environments over several years. Then we will use our newly developed methods for the analysis of soluble fiber quality to determine how environment might affect the quality and concentration of beta-glucan, especially in the newly developed high beta-glucan cultivars. Finally, we will test how beta-glucan affects the milling quality of oats. Because beta-glucan is in the cell walls of oats, it is thought to provide a strengthening effect, which reduces groat breakage during dehulling. However, high oil in oats also seems to prevent groat breakage, and currently breeders have been unable to separate the traits of high oil and high beta-glucan in oats. A collaborating genetics program has developed populations of recombinant inbred lines from oat crosses designed to be segregating for high oil and high beta-glucan. We will evaluate the phenotypes of these lines and test their behavior during dehulling to determine the relative roles of oil and beta-glucan in preventing groat breakage during oat milling.
Recent emphasis of this program has been on development of protocols for rheological analyses of beta-glucan extracts and analysis of treatments on rheological properties on beta-glucan. In particular, effects of hydrothermal treatments on groats, effects of drying of isolated beta-glucan, and the effect of growth environment of rheological properties of isolated beta-glucan have been emphasized. Measurements include apparent viscosity in flour slurries with a spindle viscometer, intrinsic viscosity in soluble extracts using an Ubbelohde-type capillary viscometer, and shear viscosity analysis with a cone and plate rotational rheometer. Efforts continue to determine effects of environment on beta-glucan properties and to determine the basis for resistance to groat breakage during dehulling.
A simple laboratory test for Fusarium Head Blight resistance in wheat. Fusarium Head Blight is a common plant fungal disease affecting wheat, barley, and oats that has caused billions of dollars of crop losses over the past decade. An ARS scientist in Fargo, North Dakota, in collaboration with scientists at North Dakota State University, has developed a simple laboratory method to test for resistance to this disease in wheat cultivars that involves growing the fungus in the laboratory on gels containing bran from wheat genotypes being selected for resistance properties. Fungal growth is lower in cultures containing bran of wheat genotypes more resistant to Fusarium infection. The method is cheaper and simpler than tests currently used to test for Fusarium resistance and may accelerate development of Fusarium resistant cultivars.
Effects of hydrothermal treatments on oat soluble fiber viscosity. High viscosity generated by oat soluble fiber in the gut is necessary for the health benefits attributed to oats in the diet. An ARS scientist in Fargo North Dakota, in collaboration with university scientists from Fargo, North Dakota and Ames, Iowa, have determined that hydrothermal treatments like steaming and toasting change the viscosity of oat soluble fiber. Steaming appears to make the fiber molecule stretch out where it entangles more with other fiber molecules, which enhances the viscosity. Toasting seems to make the fiber molecule fold up on itself, entangle less with adjacent polymers, and generates less viscosity. Results suggest steam treatments may enhance health benefits of oat soluble fiber.
Doehlert, D.C., Rayas-Duarte, P., Mccullen, M.S. 2011. Inhibition of Fusarium graminiarum growth in flour gel cultures by hexane soluble compounds from oat (Avena sativa L.) flour. Journal of Food Protection. 74(12):2188-2191.