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

Extraction of the nutritionally valuable and antioxidant compounds from papaya peels using conventional aqueous extraction (E) (at 20 degrees C, 50 degrees C, and 60 degrees 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 degrees C as compared to those measured at 50 degrees 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 degrees C and time of extraction of approximate to 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 degrees C) allowed a significant enhancement of the yields and antioxidant capacities of the extracted components from papaya peels even at neutral pH. (C) 2014 Elsevier Ltd. All rights reserved.