Comparison and optimization of conventional and ultrasound assisted extraction for bioactive compounds and antioxidant activity from agro-industrial acerola (Malpighia emarginata DC) residue

- The agro-industrial acerola residue can be used as a source of bioactive compounds.
- Ultrasound allowed higher extraction yields with lower times.
- The optimization of extraction conditions with three-factors-five-levels was studied.
- The optimal conditions for extraction of bioactive compounds were established.
- The experimental values were consistent with the expected values.

The acerola (Malpighia emarginata DC) residue resulting from the processing of pulp and juice possesses high concentrations of bioactive compounds. The use of this residue could increase its commercial value and hence result in the profitability of processing. This study was aimed to compare the conventional (CE) and ultrasound assisted extraction (UAE) for bioactive compounds and antioxidant activity from acerola residue and to optimize the best extraction method using the response surface methodology (RSM) and desirability function. The selection of the extraction method was based on designing experiments. A central composite rotatable design (CCRD) was employed to investigate the effects of eight independent variables. The extracts obtained by UAE contained higher concentrations of bioactive compounds and antioxidant activity. Ethanol concentration (X1), ethanol-residue ratio (X2) and extraction time (X3) significantly affect response variables. The quadratic model was fitted for most responses. The ethanol concentration of 46.49%, ethanol-residue ratio of 8.66 mL/g and extraction time of 49.30 min were standardized as optimal conditions. The optimized conditions model showed a good correlation between the predicted and experimental values. Overall, these results demonstrate the efficacy and better utility of agro-industrial acerola residue in the form of extraction of bioactive compounds with better antioxidant activity.

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