Influência de sais de sódio no equilíbrio de fases de sistemas aquosos bifásicos contendo Triton X-114, na presença ou não de glicose, visando a extração da enzima frutosiltransferase

Abstract

Fructooligosaccharides are prebiotic sweeteners produced by transfructosylation of sucrose by the enzyme fructosyltransferase. An alternative with fewer steps, lower cost and simpler scheduling to the conventional methods for the extraction and purification of this enzyme is the liquid-liquid extraction using two-phase aqueous systems. The first step in the attempt to make this process viable is the knowledge of the liquid-liquid equilibrium behavior of the systems. Thus the focus of the present work is the study of liquid-liquid behavior of systems constituted by surfactant Triton X-114 + water + salts (sodium sulfate, sodium citrate or sodium tartrate) at temperatures of 10 ° C, 20 ° C and 30 ° C, and pHs of 5, 7.5 and 10. Additionally, the effect of glucose, a component present in the medium from which the enzyme is extracted, was studied in the liquid-liquid equilibrium of these systems. In this study, the composition of the binodal curves were obtained by turbidimetric titration, the composition of the tie lines were calculated using the Merchuk methodology and the glucose concentration in the phases was obtained by reaction with DNS reagent, and readings in spectrophotometer UV / VIS at 540 nm. It was observed that had showed higher salting out effect on Triton X-114 and and had showed similar behavior. At low carbohydrate concentrations, this component is preferentially partitioned in the polymer rich phase. Only pH 5 had an effect on the binodal curves of the system containing sodium citrate. The Merchuk methodology for calculations of the tie lines composition correlated adequately with experimental data from the literature. The decrease in temperature of the system led to an increase of the slope of the tie lines and a decrease of the biphasic region to the systems constituted by Triton X-114 + water + salts.