"Intensification of Vaporization by Decompression to the Vacuum" (IVDV), a novel technology applied as a pretreatment to improve polyphenols extraction from olive leaves. (16th April 2021) - Abi-Khattar, Anna-Maria
Graphical abstract: Highlights: IVDV pretreatment enhances the recovery of polyphenols from olive leaves. IVDV induces a strong damage of olive leaves microscopic structure. IVDV intensifies the recovery of oleuropein and hydroxytyrosol. IVDV-treated leaves extracts demonstrated higher antioxidant activities compared to untreated leaves extracts. Abstract: Impact of the "Intensification of Vaporization by Decompression to the Vacuum" (IVDV) on extraction of polyphenols from olive leaves was investigated. Using Response Surface Methodology, the effect of three variables were studied: initial water content of leaves, processing time and steam pressure on total phenolic content (TPC). Extractions of TPC from leaves were achieved either using 100% water as a solvent (w100 ), or 50% (v/v) aqueous ethanol (w50 ). Following IVDV pretreatment, TPC yields were enhanced with both solvents by approximately 3 times compared to the negative controls. Furthermore, oleuropein and hydroxytyrosol were intensified by up to 600% and 238% respectively. Antioxidant-antiradical assays revealed higher activities, up to 3.5 times, in extracts from IVDV-treated leaves. Calculation of the extraction indices Zp, reflecting cellular damage, confirmed the beneficial effect of IVDV on the extraction yield. Finally, Scanning Electron Microscopy (SEM) permitted the morphological observation of IVDV-treated as compared to untreated leaves.