High voltage electrical discharges followed by deep eutectic solvents extraction for the valorization of pomegranate seeds (Punica granatum L.)

This work proposes a sustainable methodology based on the use of high voltage electrical discharges (HVED) and deep eutectic solvents (DES) for the simultaneous extraction of proteins and polyphenols from pomegranate seeds. Pomegranate seeds were firstly pretreated with HVED and, next, submitted to a solid-liquid extraction using DES. HVED pretreatment was compared with ultrasounds observing a better performance of HVED that promoted the disintegration of 86% of cells at 160 kJ/kg energy input and, consequently, the release of 70% of proteins and 78% of polyphenols. Extraction/solubilization of proteins and polyphenols was carried out using 5 different DES and results were compared with the obtained using NaOH. DES improved the diffusivity of both proteins and polyphenols, although the highest rates were observed for proteins, while NaOH extracted higher amounts of both. Application of RP-HPLC-ESI-Q-TOF to the analysis of extracts enabled to identify 30 different phenolic compounds among extracts, most of them ellagitannins. Proteomics enabled to identity a total of 11 different proteins among pomegranate seed extracts that were mainly assigned to globulins and albumins, with nutrient reservoir activity.

Automated summary

This study presents a sustainable methodology that combines high voltage electrical discharges (HVED) and deep eutectic solvents (DES) for the extraction of proteins and polyphenols from pomegranate seeds. HVED pretreatment was found to be more effective than ultrasounds in promoting cell disintegration and the release of proteins and polyphenols. The use of DES improved the diffusivity of proteins and polyphenols, with the highest rates observed for proteins. RP-HPLC-ESI-Q-TOF analysis identified 30 different phenolic compounds and proteomics identified 11 different proteins in the extracted samples.