Method of pectin esterification determination degree by titrated acidity.

Introduction. Studies have been conducted to develop a method for determining the pectin esterification degree in order to limit the use a significant number of costly and hardly available reagents. Materials and methods. The samples of apple and citric pectin were exhibited at Kyiv market with the different degree of esterification according to accompanying documentation. IR-spectroscopy research was provided on device Nexus-475 Nicolet firm. NMR-spectrums were registered by NMR-spectrometer Mercury, VARIAN firm. Mathematical treatment of the results is done according to mathematical modeling concept. Results and discussion. In the IR spectrum of low-esterified pectin, this band is low intensity and is in the oscillations region of 1686.71 cm-1. In spectrum of high-ester pectin the intensive line with three maximums at 3400.56 cm-1, 3316.52 cm-1, 3271.70 cm-1, which corresponds to stretching vOH. In IR-spectrums with esterification till 42% the line of free carboxyl group is available, in IR-spectrums of high-esterified pectin there is an intensive line of carboxylate groups (CO2-), and that differs the given spectrums. The given characteristics of NMR-spectrums show the difference in structure of high- and low-esterified pectin, but it does not give an opportunity to conduct the quantitative determination of esterification degree. While analyzing the results we can make a conclusion that the degree or hyperbolic models are the best for prognosing. The difference between chemical method of esterification degree determination and suggested method is 0.6-1.3%. Conclusions. Determination of the pectin degree esterification is possible by tyranic acidity with subsequent calculation by the regression equation. [ABSTRACT FROM AUTHOR]