Pressurized Liquid Extraction Optimization from Supercritical Defatted Olive Pomace: A Green and Selective Phenolic Extraction Process

Nikolaos Katsinas, Andreia Bento Da Silva, Amalia Enríquez-De-Salamanca, Naiara Fernández, Maria Rosário Bronze, Soraya Rodríguez-Rojo

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)
142 Downloads (Pure)

Abstract

Olive pomace (OP) is the main by-product of the olive oil industry produced in large quantities. Its valorization as a source of phenolic bioactive compounds is paramount for the sustainable growth of related industries. This work proposes an intensified process to maximize the recovery of phenolic compounds in dry extracts using hydroalcoholic mixtures. Supercritical carbon dioxide defatting pre-treatment was performed. Following this, pressurized liquid extraction was optimized through a circumscribed central composite design. The factors consisted of temperature (65.0-185.0 °C), ethanol percentage (8.0-92.0%), and solid/liquid ratio (0.2-0.8 gOP/mLSOLVENT). Besides the total phenolic content (TPC) and the total flavonoid content (TFC), the major phenolic compounds of OP [hydroxytyrosol (HT), tyrosol (TY), and oleuropein (OL)] were evaluated. Further, decarboxymethyl OL aglycone dialdehyde (3,4-DHPEA-DEDA) was identified by HPLC-DAD-MS/MS as the most abundant polyphenol and was studied for the first time for OP. Different conditions were found to optimize each key compound. In 67% shorter extraction time and 38% less solvent consumption compared to conventional extraction, an increase of 475% for OL, 428% for HT, 194% for TY, 373% for 3,4-DHPEA-DEDA, 89% for TPC, and 158% for TFC was observed. The antioxidant activity by oxygen radical absorbance capacity (ORAC) assay increased 89% (optimal conditions) and correlated with TPC, 3,4-DHPEA-DEDA, and TFC. Thus, an efficient, selective, scalable, and green extraction process was established.

Original languageEnglish
Pages (from-to)5590-5602
Number of pages13
JournalACS Sustainable Chemistry & Engineering
Volume9
Issue number16
DOIs
Publication statusPublished - 26 Apr 2021

Keywords

  • antioxidant capacity
  • decarboxymethyl oleuropein aglycone dialdehyde (oleacein)
  • hydroxytyrosol
  • oleuropein
  • olive pomace phenolic compounds
  • pressurized fluid extraction

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