Christo Kratchanov

Application of polyuronides as optically active ion exchangers

Abstract Studies on the chromatographic resolution of the racemic methyl esters of threo - and erythro --3-amino-2,3-diphenylpropanoic acids, threo - and erythro -3-amino-1-propanols and the medicinal compound of threo configuration ritalin (methyl phenidate) on the polyuronides polygalacturonic (pectic) acid and alginic acid, were carried out. The resolution of the racemic bases was shown to be possible in the cases being studied. The effectiveness of chromatographic resolution was mainly dependent on the degree of swelling of the polyuronide and the moisture content of the eluent. A difference was observed in the behaviour of both polyuronides towards the racemic amino bases of threo and erythro configuration; this difference could help in providing evidence for the erythro or theo configuration of compounds analogous to those studied in the present work.

Emulgierfähigkeit von Äthylestern des Sonnenblumenpektins

SummaryIt has been shown that the studied ethylesters (ethylpectins) have far better emulsifying properties than the initial sunflower pectin.The dispersity, viscosity and stability of the emulsions increase with increasing concentration of the ethylpectins and the oily phase. It has been found that the emulsifying properties of ethylesters of the sunflower pectin depend also on the degree of esterification. Best results are achieved with derivatives which have a degree of esterification of about 65%.ZusammenfassungEs wurde nachgewiesen, daß die untersuchten Äthylester (Äthylpektine) wesentlich bessere Emulgiereigenschaften als das Ausgangs-Sonnenblumenpektin haben. Die Dispersität und die Viscosität der Emulsionen erhöht sich mit der Konzentration der Äthylpektine und der Ölphase. Die Stabilität der Emulsionen wird bei steigender Konzentration von Äthylpektin und Ölphase verbessert. Es wurde festgestellt, daß die Emulgierfähigkeiten von Äthylestern des Sonnenblumenpektins auch vom Veresterungsgrad abhängen. Die besten Ergebnisse erzielt man mit Derivaten, die einen Veresterungsgrad von etwa 65% haben.

An opportunity for simultaneous purification and deesterification of pectic substances

Abstract The possibility of simultaneous purification and deesterification of apple pectin under conditions of acid chromatographic elution in a column filled with the pectic substances subjected to purification was investigated. Elution was done with diluted hydrochloric solutions of ethanol and isopropanol and the effect of temperature, acid concentration and process duration was studied. Two types of commercial pectins with different degrees of esterification were used. The dependence between purity, degree of esterification (DE) and the gel strength (GS) of the purified pectic preparations was investigated. It was shown that the gel strength increases with increasing purity, but only to a finite value of DE. The GS maximum as a function of DE depends on the type of initial pectin. The process of deesterification was studied kinetically and the rate constants were calculated on the basis of an equation describing reactions of the first order. The results obtained indicate that deesterification takes place faster in an isopropanol medium than in an ethanol medium for both types of pectin. The rate constants of deesterification also depend on the initial degree of esterification, deesterification taking place more quickly with highly esterified pectins than with moderately esterified ones.

Application of polyuronides for removing heavy metals from vegetable oils. III: Application of alginic acid, pectic and pectinic acids for demetalization of hydrogenated sunflower oil

ZusammenfassungEs wurden Laboruntersuchungen zur Entfernung von Schwermetallen aus hydrierten pflanzlichen Ölen mit hydratisierten Polyuroniden (Quellungsgrad von 4 bis 12,8 ml/g) wie z. B. Alginsäure, Pecto- und Pectinsäuren durchgeführt. Es wurde der Einfluß des Polyuronids, des Veresterungsgrades und der Bearbeitungsart des Öles auf den Entmetallisierungsgrad verfolgt. Es wurde gezeigt, daß mit dem Veresterungsgrad des Polyuronids die Entmetallisierung herabgesetzt wird. Bei einer zwei- und dreifachen Bearbeitung des hydrierten Öles mit Pectinsäure wird die Entferung der Schwermetalle weitgehend erreicht. Es wurde auch die Möglichkeit für eine effektive Entmetallisierung von hydrierten Ölen durch Bearbeitung mit wäßrigen Lösungen von Pectinsäuren bewiesen. Der Grad der Entfernung der Metallionen erhöht sich mit einer Verringerung der Konzentration der Pectinsäuren im Wasser.SummaryLaboratory experiments have been carried out for the removal of heavy metals from hydrogenated vegetable oils using hydrated polyuronides (degree of swelling from 4 to 12.8 ml/g) such as alginic acid, pectic and pectinic acids. The effect of the type of polyuronide, degree of esterification and oil treatment on the degree of demetalization has been studied. It has been shown that with increase in the degree of esterification of the polyuronide the efficiency of demetalization decreases. The second and third treatment of the hydrogenated oil with pectinic acid resulted in a high degree of heavy metal removal. The possibility of efficient demetalization of hydrogenated oils by treatment with water solutions of pectinic acids has also been demonstrated. The degree of metal ion removal increases with decreasing concentration of pectinic acids in the water solution.

Optimization of the xanthan biosynthesis using Xanthomonas Campestris pv. Vesicatoria 36

Abstract Optimized regression models describing the biosynthesis of the microbial polysaccharide xanthan have been obtained by means of mathematical planning of the experiment FFE 2 4 (full factor experiment) and a modified simplex method. In the optimized medium and cultivation mode the yields of raw and pure product increase by 35.0–33.4% in comparison with the control. The carbon conversion rate and the postfermentation liquids viscosity increase by 16.8 and 37.1% respectively, in comparison with the initial values. It has been proved statistically that citric acid stimulates the growth of the strain producer, and not the C-transformation.

Application of polyuronides for removing heavy metals from vegetable oils II. Application of chemically modified polyuronides for demetalization of hydrogenated sunflower oil

ZusammenfassungEs wurde die Möglichkeit untersucht, Schwermetalle aus hydrierten pflanzlichen Ölen mit chemisch modifizierten Pectinen zu entfernen und zwar mit Epichlorhydrin vernetzten Pectinsäuren unterschiedlicher Herkunft (aus Sonnenblumenkernen, Äpfeln, Sellerie und amidierten Pectinen mit verschiedenem Amidierungsgrad). Es wurde eine hohe Entmetallisierung von 78 bis 94% erreicht. Dabei wurde festgestellt, daß die Entfernung der Schwermetalle Cu, Fe, Zn und Ni von der Art der chemischen Modifizierung des Pectins abhängig ist. Die besten Ergebnisse wurden mit amidierter Pectinsäure erzielt.SummaryThe possibility of heavy metal removal from hydrogenated vegetable oils with the help of chemically modified pectins was studied. These included pectic acids of different origin, sunflower, apple and celery, crosslinked with epichlorohydrin, as well as amidated pectins with different degrees of amidation. The degree of oil demetalization obtained was high- from 78% to 94%. It was found that the removal of the heavy metals Cu, Fe, Zn and Ni depended on the type of chemical modification of the pectin. The best results were obtained with amidated pectic acid.