Extraction and separation of the phenolic compounds punicalagin and ellagic acid from pomegranate peel (Punica Granatum L) using modern techniques and alternative solvents

Author(s)

Isadora Lopes de Oliveira

• Document type: Master's Dissertation
• Press: Limeira, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Aplicadas
• Defense date: 2024-08-26

Examining board members

Maurício Ariel Rostagno; Alessandra Lopes de Oliveira; Samantha Cristina de Pinho

• Advisor: Maurício Ariel Rostagno; Juliane Viganó

Abstract

The peel of the pomegranate (Punica granatum L.) is a by-product rich in bioactive compounds such as flavonoids (quercetin), ellagitannins (mainly punicalagins), phenolic acids (caffeic, chlorogenic, coumaric, ellagic, gallic and quinic) and anthocyanins (delphinidin, cyanidin and pelargonidin). Specifically, punicalagins and ellagic acid are compounds of high interest due to their antifungal, antimicrobial, and biological properties. Thus, this study proposes the development of methods for separation and recovery of selective fractions of ellagic acid and punicalagins and their application in active packaging. The first part of the study aimed to fractionate the pomegranate peel extract using a eutectic mixture of glycerol:betaine (1:2) and ethanol. For this purpose, dried and ground pomegranate peel extract was obtained in an ultrasonic bath using water as solvent at a solid/liquid ratio equal to 20 mL/g and 60 ºC, 100 W, 37 kHz, for 60 min. The resulting extract was submitted to the adsorption process using 7.5 mL of extract and adopting the following variables: adsorbent type (Porapak RXN RX Bulk and Sepra C18-E), adsorbent mass (0.1, 0.2, 0.3, 0.4 and 0.5 g), temperature (20, 40 and 60 ºC), pH (4.6 and 8). After adsorption, desorption was evaluated using a eutectic mixture of glycerol:betaine (1:2) with 50% (w:w) and pure ethanol (100% w:w). The compounds retained in the adsorbent in the desorption process were submitted to homogenization in a Falcon tube (15 mL) vortex for 5 min and centrifuged for 20 min at 25ºC. at 10000 rpm. This stage of the work showed that the adsorption adopting 0.5 g of Porapak RXN RX Bulk, pH equal to 4 and 20 ºC promoted total adsorption of the target compounds. While desorption with eutectic mixture glycerol:betaine (1:2) (50% w:w) promoted selective recovery of punicalagin and hydroalcoholic solution recovered ellagic acid. The second stage of the work aimed to develop a method combining the techniques of ultrasound-assisted extraction (UAE) and extraction with pressurized liquids (PLE). At UAE, a screening with 5 types of choline chloride-based natural eutectic solvents (NaDES) was performed. The NaDES that obtained the highest recovery of the target compounds (choline chloride:glycerol (1:2) with 40% of water) was adopted as solvent in the PLE by varying the temperature (20-160 ºC) at 1500 MPa and 20 min. PLE at 80 ºC achieved the highest extraction yield of the target compounds. With this, it was possible to demonstrate the importance of punicalagins and ellagic acid compounds present in pomegranate peel and the potential of green solvents (AU)

• FAPESP's process: 21/13638-0 - Development of active packaging through the extraction of bioactive compounds from pomegranate peel (Punica granatum L.)
• Grantee: Isadora Lopes de Oliveira
• Support Opportunities: Scholarships in Brazil - Master