Comparison of Conventional Microwave and Focused Microwave-assisted Extraction to Enhance the Efficiency of the Extraction of Antioxidant Flavonols from Jocote Pomace (Spondias purpurea L.).

Jocote (Spondias purpurea L.) is rich in phenolic compounds which have antioxidant properties. The focused microwave-assisted extraction (FMAE) was compared with the conventional microwave-assisted extraction (MAE) to obtain flavonols from jocote pomace. The effects of parameters such as the extraction time, the temperature and the composition of the solvent mixture (i.e., the ethanol to water ration) were evaluated and optimized using a statistical experimental design approach. Response surface methodology (RSM) was applied to determine the important effects and interactions of these independent variables on the extractive yield and quantification of some flavonoids. In addition, the antioxidant activity was analyzed. The total phenolic and flavonoid content was determined according to the Folin-Ciocalteu and aluminum chloride methods, respectively. The free radical scavenging activity of the extract was evaluated according to the DPPH assay. The results showed that the optimum extracting parameters used FMAE with extraction time of 20 min, temperature of 68 °C and ethanol composition of 80% in water. Under these conditions, a yield of 3.42% was obtained. Rutin and quercetin were quantified (0.19 mg/mL and 0.024 mg/mL, respectively) through HPLC-DAD. The total phenol and flavonoid contents were found to be 0.897 g GAE/g and 1.271 g QE/g, respectively. In the DPPH scavenging assay, the IC50 value of the extract occurred at 43.10 μg/mL. This study shows that FMAE is suitable as an efficient extraction procedure for the extraction of flavonols from jocote pomace.