Impact of pulsed electric fields and high voltage electrical discharges on extraction of high-added value compounds from papaya peels

• Pulsed electric technologies have the potential to recover high-added value compounds from papaya peels.
• HVED exhibited the highest recovery of proteins, total phenolics and carbohydrates.
• Two-stage PEF + supplementary aqueous extraction at 50 °C showed a good recovery of high-added value compounds.

Extraction of the nutritionally valuable and antioxidant compounds from papaya peels using conventional aqueous extraction (E) (at 20 °C, 50 °C, and 60 °C) and extraction assisted by pulsed electric field (PEF) or by high voltage electrical discharges (HVED) was studied. Increase of extraction temperature or extraction in basic media (pH = 11) not always resulted in an increase of the yields or TEAC values. E.g., the concentration of proteins and TEAC values at pH = 7 and pH = 11 were noticeably smaller at 60 °C as compared to those measured at 50 °C. HVED-assisted technique showed a higher extraction efficiency of high-added value compounds compared to PEF-assisted extraction. E.g., the concentrations of proteins obtained for the HVED- or PEF-assisted extractions were 60 mg/L and 20 mg/L, respectively (pH = 7 at 20 °C and time of extraction of ≈ 3/4 h). The better efficiency of HVED-assisted extraction can reflect turbulation of suspension and fragmentation of pills provoked by electrical discharges. However, electrical discharges may produce chemical products of electrolysis and free reactive radicals, which can reduce the nutritional quality of high-added value compounds. Application of the two-stage method (PEF + supplementary aqueous extraction at 50 °C) allowed a significant enhancement of the yields and antioxidant capacities of the extracted components from papaya peels even at neutral pH.