Extração de compostos bioativos a partir do resíduo agroindustrial da polpa de morango (Fragaria spp.) empregando solvente eutético natural profundo (NADES) e ultrassom

Abstract

Strawberry is a fruit that has good nutritional properties, this is due, among other things, to the presence of antioxidant compounds in the constitution of the fruit. Currently there is a concern to minimize industrial waste, as well as nutritionally improve processed foods, adding to these bioactive compounds, for example. In this sense, the general objective of this study was to perform the extraction of bioactive compounds from the agro-industrial residue of strawberry pulp (Fragaria spp.) using natural deep eutectic solvent (NADES) and ultrasound. For this purpose, a NADES was prepared from choline chloride and lactic acid. Then the extraction of the bioactive compounds was performed by adding the NADES to the dried and standardized strawberry pulp residue, in the proportion 5% (w/v), after the mixture was placed in an ultrasonic bath. The same process was performed using ethanol and water instead of NADES. After extracting the active compounds, centrifugation was performed to separate the residue from the extract (solvent containing the bioactive compounds). Then the extracts were analyzed for antioxidant capacity by FRAP+ analysis (Iron Reduction Method), total phenolic compounds by Folin-Ciocalteu analysis, and flavonoids by analysis of total flavonoids. For each analysis a calibration curve was constructed using Trolox, gallic acid and quercetin as standards, respectively. The results obtained were statistically analyzed by analysis of variance anova, and when it showed a significant difference between the extracts, the Tukey test was performed. Evaluating the results of FRAP+ and statistical analysis, it was observed that all extracts showed antioxidant capacity, and the extract obtained using NADES showed a higher numerical value, and the anova indicated that there is a significant difference between treatments, as per the Tukey test this difference was verified only between NADES and ethanol, and between NADES and water, but not between ethanol and water. Regarding the total phenolic compounds, it was possible to perceive from the results of the Folin-Ciocalteu analysis that the three solvents used were able to extract phenolic compounds, but the ANOVA result showed that there was no significant difference between the treatments. The results of the analysis of total flavonoids showed the presence of flavonoids in all extracts, and the extract obtained with NADES showed higher values than those obtained with ethanol or water, and by anova there is a significant difference between treatments, with a difference between all them by the Tukey test. Thus, it can be concluded that the process used using NADES and ultrasound is simple and was adequate for the extraction of active compounds from the strawberry pulp residue. This study also demonstrated that the studied NADES solvent has potential for the extraction of these compounds, since higher values of antioxidant capacity and total flavonoids were obtained for the extract obtained with NADES when compared to those obtained with ethanol or water.