Extração sequencial convencional e assistida por ultrassom de antocianinas e pectina de casca de jabuticaba (Plinia cauliflora) pré-tratada por diferentes métodos

Abstract

Jabuticaba is a fruit native to Brazil, much appreciated for fresh consumption and in the production of jellies, liqueurs, pulps and wines. The bark, residue from the processing, has pectin and is rich in anthocyanins, substances that can be used as sources of commercially valuable products. Due to the perishability of the bark, it is necessary to apply conservation processes, if it is not possible to extract bioactive compounds right after pulping. Drying and freezing are two alternatives for conservation, but both lead to nutritional losses and degradation of compounds of industrial interest. On the other hand, these techniques cause changes in cell structure that can facilitate solvent permeability, improving extraction efficiency. Therefore, the objective of this work was to study the effect of pre-treatment (drying, freezing) and in natura use of jabuticaba peel for sequential extraction of anthocyanins and pectin, by conventional extraction (180 rpm agitation at 25 ± 1 ° C, for 2 hours) and assisted by ultrasound (frequency of 20 kHz and power of 160 kW, for 12 minutes) applied in the extraction of bioactive compounds followed by the extraction of pectin from the residue. In the selection of the raw material preparation and the extraction process, a 3 x 2 factorial design was used, with three types of pretreatment (dry, frozen and in natura peel); and whether or not to use ultrasound in the sequential extraction of anthocyanins and pectin. After selecting the pre-treatment and extraction type, the extraction of phenolic compounds and anthocyanins and their effect on the sequential extraction of pectin from the residue will be optimized. The fresh bark was analyzed for proximate composition, pectin, water activity, pH and color. After the extractions, the extracts were characterized for total anthocyanins content, total phenolic content, antioxidant activity via DPPH and ABTS and color, and the residues (raffinate phase) were used for sequential pectin extraction. The extracted pectin was quantified and its degree of esterification determined. The use of fresh jabuticaba peel favored the sequential extraction of anthocyanins and pectin. Under the conditions evaluated, ultrasound-assisted extractions were not efficient. In the optimization of conventional extraction of compounds of interest, fresh jabuticaba peel was used through a Central Composite Rotational Factorial Design (DCCR). The effects of the mass fraction of ethanol (X1) and hydrochloric acid (X2) in an aqueous solution were studied in the extraction of total anthocyanins, total phenolic content, antioxidant activity via ABTS and FRAP, and the residues (raffinate phase) were used for extraction. pectin sequence. Extracted pectin was quantified and its degree of esterification was determined. The pectin obtained with higher and lower yields, and higher and lower degrees of esterification, was characterized as to the degree of esterification by the Fourier Transform Infrared Spectrometry (FTIR) methodology. The sequential extraction of pectin from anthocyanin extraction residue is promising, since during anthocyanin extraction, pectin was not degraded. This result was confirmed through FTIR spectra, which prove that the extracted biopolymer is pectin. Extraction with ethanol contents below 50% is ideal for extracting phenolic compounds and anthocyanins, as low acid concentrations in the solution result in extracts with greater antioxidant activity.