[Prebiotics as functional food ingredients: terminology, choice and comparative evaluation criteria, classification].

The purpose of this review is to analyze current concepts of prebiotics as one of the most promising groups of functional food ingredients, identify problems and trends in the investigations in this area. The background for the emergence and development stages of the concept of «prebiotics» as non-digestible food substances that selectively stimulate the growth and (or) the biological activity of one or a limited number of representatives of the protective microflora of the human intestine, contributing to the maintenance of its normal structure and biological activity is shown. The criteria for selecting prebiotics and the formula for prebiotic index determining are presented. Methods for determining the bifidogenic properties of functional foods enriched with probiotic microorganisms or prebiotic substances are described. Prebiotics are classified according to several factors: nature and structure, origin and sources of raw materials, the method of production, the field of application. It is shown that most researchers consider prebiotics only as substances of carbohydrate nature, primarily indigestible oligosaccharides. A brief description of the most studied prebiotics (fructans, galactans and lactulose) is given. The information on technological properties of oligosaccharide-prebiotics is generalized. It is shown that prebiotics belong to the fast growing segments in the world market of functional ingredients, however their production and use in Russia is still at the initial stage of development. The main tasks in the field of prebiotics researches are defined: clarifying the definition, improving the methods for analyzing their chemical composition, study of the effectiveness and mechanisms of influence on the intestinal microbiota, especially on the interaction in the «macroorganism-microbiota» system using modern molecular genetic methods; scientific substantiation of the possibility of prebiotics using for the prevention and treatment of alimentary-dependent diseases. For the practical implementation of these tasks, it is necessary to develop new cost-effective methods for the production of prebiotics and synbiotics, as well as food technology with their use.