Partição de antocianinas de açaí utilizando equilibrio líquido-líquido a base de solventes eutéticos profundos

Abstract

The anthocyanin in the acai fruit is one of the most attractive industrial compounds. It is used as a natural dye due to its violet pigment and its antioxidant power. An alternative technique for the extraction of biomolecules is extraction using Liquid Liquid Equilibrium (LLE) systems, composed of Deep Eutectic Solvents (DESs) characterized by being economical, efficient and of low toxicity to the environment and human body. Therefore, this study aimed to determine liquid-liquid equilibrium data of DES-based systems: ChCl:GLI (choline chloride:glucose) + isopropanol + water and ChCl:SAC (choline chloride:saccharose) + isopropanol + water at temperatures of 25oC and 35oC, and to assess its application in the partition of the acai anthocyanins. First, the physical-chemical characterization of the lyophilized acai was carried out. Second, Box Behnken factorial design was applied to analyze and optimize the extraction process to evaluate the influence of experimental conditions on the extraction of anthocyanin and total polyphenols from the lyophilized acai. Once the optimization conditions were found, the DESs that would be used in the LLE system were prepared. Furthermore, the thermal and structural properties for each DESs were determined with DSC and FTIR respectively. Third, aiming to research DESs behavior with water and isopropanol mixtures in equilibrium phases, the LLE data at 25 oC and 35oC were determined. The binodal curves were obtained by cloud point titration, and the tie lines were determinate for gravimetrical and analytical (HPLC and Karl-fischer) methods. The systems studied were characterized as quaternary systems and the experimental LLE data were correlated by NRTL obtaining a mean quadratic deviation (RMSD) of 0.438%. The anthocyanin partition in ELL was carried out using the anthocyanin extract obtained in optimal conditions. Finally, it was proven that the individual components of DESs have a high affinity with the anthocyanins, showing the total migration of the biomolecules in the bottom phase. The partition coefficients of total polyphenols (KPT) were higher than 1, showing the preference of biomolecules in the bottom phase and the extraction efficient (%EE) of 70% with ChCl + Glucose + isopropanol + water system. This result confirmed xithe potential of using these systems to extract natural pigments aiming at a probable use of the separation of nonpolar biomolecules (acai lipids) in the alcohol-rich phase.