DETERMINATION OF SOME PHYSICAL AND CHEMICAL PROPERTIES OF PECTIN SUBSTANCES FROM THE SOLVENT CAKE OF TAGETES PATULA L. INFLORESCENCES

Abstract

Big molecular weight conditions are responsible for some properties, which are absent in low molecular compounds. Therefore, its determination allows revealing of some physical and technological properties of biopolymers and prediction of the possibility of their practical application. The aim of this work was to determine an average molar weight, to study the superficial properties at the border of “solution-air” phases, and to establish an isoelectric spot of water solutions of pectin substances (PS), isolated from a solvent cake of Tagetes patula inflorescences. Materials and methods. Polysaccharide complexes were isolated from the solvent cake of Tagetes patula inflorescences of Carmen species which was left after a raw material extraction with ethanol 40% with the method of Kochetkov and M. Sinnera. The time of water and PS solutions flow out was measured by the use of a capillary Ostwald viscosimeter; different types of viscosity were calculated. The density of solutions was determined by using a picnometric method, however due to the closeness of density of the analyzed solutions and water, they were not considered in the calculation of the relative viscosity. Series of solutions with 0.01 to 0.5% concentrations were prepared from 1% PS water solutions to determine a surface activity. Monometric liquid tension variations were set in Rehbinder’s apparatus in the moment of an air bubble appearance on the surface of PS solution. Isoelectric spot (IES) of PS was determined in acetate buffer solution with pH within 3.2 to 6.2 by using the viscometer method. Results and discussion. Fractioning of the obtained polysaccharide complexes showed that efficiency of the pectin substances amounted to 2.2%. Calculation shows that an average molar weight of PS amounted to 45272 g/mol. About the degree of interaction between macromolecules of polymer and solvent, structural properties of macromolecule, the degree of its branching can be judged by the value of Huggins test. The value was found to be 1.46, which proves the low solubility of PS in water. Apparently, a biopolymer chain has been branched which worsen the solubility of macromolecules and further may promote the formation of gel condition. PS, isolated from the solvent cake of Tagetes patula, belong to the group of the surface active substances. Due to a big cross section of a molecule (S) and the high average molar weight, (45272 g/mol) molecules occupy a big volume at the surface of phase separation. We have established that macromolecule is in the isoelectric state at pH = 4.7. Conclusion. In the result of the studies using viscometer method, we have determined a molar weight of PS equal to 45272 g/mol. Huggins constant (1.46) which is connected to a low solubility of PS in water has been determined. We have established that PS, isolated from the solvent cake of Tagetes patula, are surface active. We have shown that PS macromolecule is in the state of polyamphion at pH = 4.7.