Methods for Preparing Phenolic Extracts from Olive Cake for Potential Application as Food Antioxidants

Abstract

Olive cake, the most important byproduct of olive oil extraction by the two-phase centrifugation system, was used to obtain phenolic extracts. The extracts were obtained using the two constituents of this waste, vegetative water and solid residue, to maximize the extraction of all phenolic compounds. Different extraction procedures were studied, a simple and rapid extraction procedure being developed from the solid residue using an accelerated solvent extractor (ASE). Afterward, the phenolic extracts were fractionated using semipreparative HPLC to study the antioxidant activity of the different components. The identification of the phenolic compounds was carried out with an ultraperformance liquid chromatograph coupled to tandem mass spectrometry equipment (UPLC-ESI-MS/MS). With this method, a complete list of the polyphenols from the extract was obtained. Finally, the antioxidant activity of the phenolic extracts and the isolated fractions was evaluated, showing great antioxidant capacities, between 3450 and 17900 micromol of Trolox equivalents/g of extract. With regard to the isolated fractions the most antioxidant were those that contained hydroxytyrosol and 3,4-DHPEA-EDA. The suitability of the solid residue extract obtained by the ASE procedure was demonstrated given the great range of phenolic compounds and the feasibility of production on an industrial scale.

Current options for the valorization of food manufacturing waste: a review

“…food and cosmetic) or animal feed, but also could contribute to minimize the environmental impacts of this agro-industrial waste. Olive cake was used also to obtain phenolic extracts from its vegetative water and solid residue, to maximize the extraction of all phenolic compounds (Suárez et al, 2009). The authors studied different extraction procedures, a simple and a rapid one, and they found that the phenolic extract obtained by accelerated solvent extraction from the solid residue of olive cake could be proposed as a simple and rapid extraction procedure as an alternative to solid-liquid extraction.…”

Identification and characterisation of phenolic compounds extracted from Moroccan olive mill wastewater

“…The concentration of total phenol content ranged from 13 to 22 % depending on the geographical area. They were characterized by their highest antioxidant activity, especially hydroxytyrosol, and some other biological effects such as antimicrobial and anti-inflammatory activities (Allouche et al, 2004;De Marco et al, 2007;Capasso et al, 2002;Suarez et al, 2009;Visioli et al, 2002).…”

“…Different letters mean significant differences (P < 0.05) (Student test). (Dermeche et al, 2013;Obied et al, 2005;Suarez et al, 2009;Obied et al, 2007) a The Results are expressed as percentage of total phenols in OMMW extracts. b Mass charge value.…”

“…Both compounds exhibited a good antioxidant potential McDonald et al, 2001). The MS analyses of mountainous extracts showed molecular ions at m/z 269, 431 and 577 suggesting the presence, respectively, of apigenin (0.38 % of the total phenols content) and its two derivatives: apigenin-7-glucoside and apigenin-7-rutinoside detected at variable amounts (Dermeche et al, 2013;Obied et al, 2005;Suarez et al, 2009).…”

“…The spectra generated from plain OMWW extracts gave the deprotonated molecule at m/z 377 (peak 24) corresponding to the oleuropein aglycon (3,4-DHPEA-EA) Suarez et al, 2009). Another molecule identified as an oleuropein derivative shown by its deprotonated molecule [M-H] -at m/z 319 may be attributed to oleuropein aglycone isomer in aldehyde form (3,4-DHPEA-EDA) previously identified by Servili et al (1999) in vegetation waters.…”