OAT GUM: STRUCTURE, PROPERTIES, PRODUCTION, APPLICATION IN THE FOOD INDUSTRY

Abstract

Oat gum (β-glucan, glycan) belongs to the group of soluble dietary fibers. Due to their important functional properties, cereal β-glucans are used to reduce the level of cholesterol in the blood, alleviate the symptoms of diabetes, lower blood pressure, and prevent cardiovascular and oncological diseases. Sources of β-glucans are yeast, mushrooms, bacteria, barley, oats. The use of secondary resources of barley and oat processing as a source of β-glucans has both economic and environmental significance. Cereal β-glucans consist of β-D-glucose monomers connected by (1,3)- and (1,4)-glycosidic bonds. β-Glucan dissolves well in cold water and is insoluble in ethyl alcohol. It is able to form very viscous solutions at low concentrations. The viscosity of solutions depends on the concentration and molecular weight of β-glucan. The rheological properties of aqueous gum solutions do not depend on the pH of the medium. The presence of NaCl in concentrations of more than 0.5% leads to a decrease in the viscosity of solutions, and the addition of sucrose in the amount of 20-45% increases the viscosity. The technological features of obtaining β-glucans are related to the method of their extraction from natural sources. Extraction of oat gum from oat bran or rolled oats involves alkaline treatment of flour at 50-70 °C and pH 8.0-10.5, removal of starch and proteins, precipitation of oat gum with alcohol and separation by centrifugation. Solubility, degree of extraction, and yield of β-glucan from oats depend on particle size, pretreatment of grain raw materials, and extraction conditions (temperature, pH, extractants). β-Glucan is isolated from the extract by dialysis, ultrafiltration or alcohol precipitation. When using dialysis, highly viscous β-glucan is obtained, but with a lower yield; ultrafiltration and alcohol precipitation allow a higher yield of β-glucan with lower viscosity. Oat gum can be introduced into a wide range of food products to provide new functional properties and improve nutritional quality, includ ng wheat bread, bakery products, cookies, pasta, soft drinks, as a fat substitute in dairy and meat products. It performs the technological functions of a thickener, gelling agent, stabilizer or coating in food systems.