Colloidal Properties of Sophora Japanese Fruit Dispersion

Drug plant raw materials represent an important source of biologically active substances (BASs), which are used in pharmaceutical, cosmetic, food, and other industries. This paper presents the results of studying colloidal properties of crushed sophora Japanese fruits (hereinafter referred to as sophora) in order to improve the extraction of BASs. To achieve the goal, the following tasks have been set: the study of the ζ potential of sophora particles at different times of contact between the particles and an extractant and the pH values of the medium; determining the isoelectric point (IEP) of the sophora particles by electrophoresis; finding the point of zero charge (PZC) of sophora particles using potentiometric titration; and studying the influence of medium pH, sophora particle size, temperature, the presence of surfactants and ions, and the nature of an extractant on sophora swelling. The points of zero charge \({\text{(p}}{{{\text{H}}}_{{{\text{PZC}}}}}\)) of the aqueous dispersions of sophora and extracted flavonoids are 5.8 and 5.2, respectively, thus being close to the values \({\text{p}}{{{\text{H}}}_{{{\text{IEP}}}}}\). The swelling of sophora particles is limited and accompanied by the gradual fracture of the plant cells. Adsorption equilibrium is achieved within 30 min. In an alkaline region and in the presence of alcohol, the swelling of the sophora particles decreases, while it increases at elevated temperature and in the presence of NaI ions.