Otimização do processo de extração de taninos a partir da espécie Mimosa tenuiflora (Willd.) Poiret

Abstract

Tannins are polyphenolic compounds found in plants that have the ability to associate and precipitate proteins. Such compounds are widely used in leather industry, pharmaceutical industry, water treatment, among others. According to the literature, bark of the species Mimosa Tenuiflora has great potential as a producer of tannins. This species, popularly known as Jurema Preta, is a native plant that occurs in the caatinga areas of northeastern Brazil. In this context, the objective of this work was to optimize the extraction of condensed tannins from the Jurema Preta bark, aiming at its potentiality for commercial exploitation. Initially, experiments were conducted to evaluate the Total Solids Content (TST) using different concentrations of hydroethanolic solutions. For this, the dynamic maceration technique was used for all experiments. Experimental planning was also performed to study the influence of some variables, such as ethanol to water solvent ratio, solvent volume, extraction time and temperature on the extraction of Condensed Tannins (TC) and Total Polyphenols (PT), besides the effect on TST. It was used for the experimental planning the Central Rotational Composite Design (DCCR), because it allows to analyze all experimental space with smaller number of experiments. According to the results, the extracts obtained with 50% ethanol in water presented higher amounts of PT and TC compared to the other concentrations of ethanol in water. The extraction obtained with water solvent (without the addition of ethanol) was the one that obtained the lowest content of condensed tannins. The solvent volume variable was the most significant for the response variables. Higher levels of condensed tannins were obtained using lower solvent volumes. The time and temperature variables, according to the response surfaces for condensed tannins, showed no influence on the tannin extraction process, but may promote greater extraction with the application of higher temperatures and time, even with larger solvent volumes. A directly proportional relationship of the concentration of total solids and condensed tannins and total polyphenols was observed. Evaluating the highest levels of condensed tannins obtained by the planning the most viable condition, taking into account the cost of the process, to obtain higher contents of condensed tannins was: temperature 41.45 ° C, time 67.5 min, volume of 22.5 mL solvent and 25% ethanolic concentration in water. In this condition, the content of condensed tannins was 83.7 mg EC / g of dry extract.