INTRODUCTION
The problem of preservation and promotion of health and increasing life expectancy has received considerable attention worldwide since the mid-20th century. Therefore, the significance of dietary fiber that can have a beneficial effect on health as a component of functional food has increased. Cell walls of barley endosperm contain large quantities of β-glucan, a dietary fiber that has received special attention due to its ability to reduce the level of cholesterol in the blood and thereby diminish the risk of cardiovascular diseases. Moreover, recent reports show that this fiber prevents a sharp increase in blood glucose levels after food consumption [1, 2, 3]. There is scientific evidence showing that diets characterized by low glycemic index may reduce insulin resistance and prevent the development of diabetes. Research involving long-term observations of 90000 women and 45000 men showed that insulin-independent diabetes mellitus was 30% less likely to develop in people who regularly consumed cereal-based foods. The high capacity for reducing the glycemic index of foods characteristic of β-glucan is related to its ability to form viscous solutions decelerating starch hydrolysis and cholesterol absorption. The daily dose of β-glucan recommended by the U.S. Department of Food and Drug Administration is 3 g or at least 0.75 g per serving [1, 2, 4, 5].
A trend of using barley flour containing β-glucan as an alternative to wheat flour in the production of pasta, bread, and ethnic foods, has been growing during the recent years. The use of barley flour is justified from the standpoint of health benefits, but its negative effect on the structure and consumer characteristics of the products hinders its widespread use in the food industry. Therefore, current research on β-glucan-enriched foods is focused on finding ways of introducing it into the formulation so that the consumer characteristics of the final product remain similar to those of the conventional analog [2, 6, 7].
The wide prevalence of diseases caused by excess body weight, which is, in its turn, usually caused by consumption of food containing large amounts of easily digestible carbohydrates, requires changing the existing technologies in order to reduce the glycemic index of foods. The use of complex additives obtained by combining materials of plant and animal origin, for instance, puffed barley combined with eggshell powder, is one of the approaches to increasing the nutritional value of food while reducing the glycemic index. Components of the complex additive were selected using the concepts of food combinatorics which takes the mutual effects of the ingredients into account. For example, puffed barley contains the polysaccharide β-glucan capable of lowering the glycemic index of foods [2, 8, 9], and eggshell contains large amounts of calcium (more than 3 %), which requires the presence of B-vitamins [10, 11] for absorption; the content of the above named vitamins in barley may amount to 7.0 mg %. Thus, the components of the complex additive complement each other. The use of the additive described above contributes to complex enrichment of foods and the reduction of their glycemic index.
