STUDY OF SOME PHYSICAL AND CHEMICAL CHARACTERISTICS OF POLYSACCHARIDES FROM COMMON OYSTER MUSHROOMS (PLEUROTUS OSTREATUS)

Mushrooms, which are most commonly used in the culinary practices of all countries and cultures, have been unjustly neglected. Therefore, we chose mushrooms - Veshonka, which are widely available and easy to cultivate in any region - as the subject of our study. Biologically active compounds isolated from Veshonka mushrooms have a wide range of pharmacological activities. Recently, special attention has been paid to polysaccharides in the literature. The aim of our study was to isolate polysaccharides from common oyster mushrooms and to establish some of their physical and chemical characteristics. Polysaccharides in oyster mushrooms are mainly represented by a cellulose fraction, which is referred to in the literature as β-glucans. The main physical and chemical characteristics of the obtained β-glucans that influence the biological behaviour of molecules were established. The average molecular weight of the isolated polysaccharides was determined by the viscometric method. It was established that M = 5307 g/mol, M = 23229 g/mol. The distribution coefficient of β-glucans between two liquid phases (water and ethyl acetate) was determined using the conductometric method, which was K = 0.565. The degree of transition of β-glucans into the organic phase was 63.9 %. The surface activity of β-glucans was determined by the maximum air bubble pressure method using a Rebinder apparatus: the surface activity of β-glucans is 59.6·10-3 N·m2/mol. Thus, the isolated β-glucans can be used as stabilisers of dispersed systems. Using Graph version 4.4.2, the empirical constants of the Shishkovsky equation were accurately restored, which is confirmed by the low value of the root mean square error of surface tension determination (MSE = 1.25·10-3 N/m). The parameters of the adsorption layer of β-glucans were determined: the area occupied by a molecule (S = 1.74 Å 2), the layer thickness corresponding to the molecule length (l = 5054.28 Å) and the volume (V = 8794.45 Å 3). The macromolecules of the studied glucans contain more functional groups exhibiting acidic properties than those capable of attaching protons. The isoelectric point (IEP = 4.2) was determined for the isolated β-glucans, which is less than 7. Therefore, it can be concluded that β-glucans from mushrooms are polyampholites.