INTRODUCTION
Dairy products are among the most important components of human food. They account for 20% of protein supply and 30% of fat supply in the human diet. Creation of products with predefined properties and rational use of raw materials are the priority directions for the development of dairy products manufacturing technologies [1, 5, 6].
Adherence to scientifically based formulations and compliance of the final product composition with regulatory requirements concerning the composition of raw materials are among the most important issues to be controlled during the assessment of quality of dairy products. Hundreds of dairy products available on the market are in constant demand and often actively marketed; therefore sellers and manufacturers of dairy products alike are always tempted to adulterate these products. Therefore, reliable methods for the identification of raw materials found in dairy products are necessary to prevent faulty and adulterated foods from being sold [2, 7, 8, 9].
The question of reliable determination of the type of components found in dairy products is currently especially acute due to the widespread adulteration of foods with texture stabilizers. The use of these components implies adding them to foods to induce gelling of liquid systems. Structure stabilizers currently in use comprise anionic polysaccharides, both natural (pectin, agar, agaroid, and pyrophosphate) and artificial (oxidized starch). Alginates, cellulose derivatives, and carboxymethyl cellulose (CMC), as well as various gums, are widely used abroad [3, 10, 11, 12]. Classification of stabilizers can be based on one of the following criteria: description of all compounds as polysaccharide materials, assignment of names referring to botanical species, origin (plant, animal, or artificial), or chemical properties. Classification taking the origin of the stabilizers into account is currently preferred; according to this classification, all stabilizers are assigned to groups of modified natural or semi-synthetic stabilizers, chemically modified natural stabilizers or compounds similar to them, or synthetic gums obtained by chemical synthesis.
Agar is one of the classic structure stabilizers widely used in confectionery industry. However, the increasing shortage of agar sources necessitates the replacement of agar with other structure stabilizers. Various types of pectins are an example of promising structure stabilizers. They are currently used in food and pharmaceutical industry. Pectins are capable of forming gel systems characterized by a specific set of physical and chemical properties. Furthermore, pectin was shown to exert beneficial effects on the human organism, and the resources for pectin production are virtually unlimited [4, 13, 14, 15].
The aim of the present work was to compare the microstructure and composition of various structure stabilizers of plant origin for the subsequent development of procedures for the detection of adulterated products.
