Valorisation of Exhausted Olive Pomace by an Eco-Friendly Solvent Extraction Process of Natural Antioxidants

Romero

et al. 2021

Foods

Self Cite

Olive-derived biomass is not only a renewable bioenergy resource but also it can be a source of bioproducts, including antioxidants. In this study, the antioxidant composition of extracted olive pomace (EOP) and a new byproduct, the residual fraction from olive pit cleaning (RFOPC or residual pulp) was characterized and compared to olive leafy biomass, which have been extensively studied as a source of antioxidants and other bioactive compounds with pharmacological properties. The chemical characterization showed that these byproducts contain a high amount of extractives; in the case of EOP, it was even higher (52.9%) than in olive leaves (OL) and olive mill leaves (OML) (35.8–45.1%). Then, ultrasound-assisted extraction (UAE) was applied to recover antioxidants from the extractive fraction of these biomasses. The solubilization of antioxidants was much higher for EOP, correlating well with the extractives content and the total extraction yield. Accordingly, this also affected the phenolic richness of the extracts and the differences between all biomasses were diminished. In any case, the phenolic profile and the hydroxytyrosol cluster were different. While OL, OML, and EOP contained mainly hydroxytyrosol derivatives and flavones, RFOPC presented novel trilignols. Other compounds were also characterized, including secoiridoids, hydroxylated fatty acids, triterpenoids, among others, depending on the bioresource. Moreover, after the UAE extraction step, alkaline extraction was applied recovering a liquid and a solid fraction. While the solid fraction could of interest for further valorization as a biofuel, the liquid fraction contained proteins, sugars, and soluble lignin, which conferred antioxidant properties to these extracts, and whose content depended on the biomass and conditions applied.

Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Olive Pomace-Derived Biomasses Fractionation through a Two-Step Extraction Based on the Use of Ultrasounds: Chemical Characteristics

Romero

et al. 2021

Foods

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“…The mobile phase used was a ternary gradient, composed of an aqueous solution of orthophosphoric acid (0.2%, v/v), methanol, and acetonitrile. The elution flow was 1 mL/min, the oven temperature was set at 30 ℃, and the volume of sample injected was 20 µL [4]. Hydroxytyrosol was identified by comparison with it commercial standards through retention time and UV absorption spectra provided by a diode array detector.…”

Section: Phenolic Profile By Hplcmentioning

confidence: 99%

“…The main component of EOP is the extractive fraction, which accounts for 41% in a dry basis [4]. Therefore, the valorization of this agro-industrial residue implies the utilization of this fraction, which contains bioactive compounds.…”

Section: Evaluation Of the Extraction Conditionsmentioning

confidence: 99%

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Recovery of Bioactive Compounds from Exhausted Olive Pomace

Cara

The 1st International Electronic Conference on Biomolecules: Natural and Bio-Inspired Therapeutics for Human Diseases

et al. 2020

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Exhausted olive pomace (EOP) is a residue derived from the olive pomace oil industry. One of the main components of this agro-industrial residue is the extractive fraction which contains non-structural components such as bioactive compounds. In this work, different extraction methods, including green technologies, have been compared to evaluate the extraction of antioxidants from EOP: hydrothermal extraction, aqueous accelerated extraction, organosolv extraction and extraction with aqueous salt solutions. The extracts obtained were characterized regarding the content of total phenols by the Folin-Ciocalteu method. After characterization, hydroxytyrosol was found to be one of the potential active compounds in EOP.

Combined Extraction and Ethanol Organosolv Fractionation of Exhausted Olive Pomace for Bioactive Compounds

Romero

Advanced Sustainable Systems

et al. 2022

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biomass resources, including agro-food wastes, in attractive feedstock for multiproduct processes in a biorefinery system. The implementation of versatile biorefineries able to produce renewable chemicals and energy carriers requires the use of different lignocellulosic biomass sources with low cost and high availability. [1] Currently, several investigations are focused on the utilization of plants and oil wastes to generate antioxidant and antimicrobial extracts. These can be used as natural ingredients with health-promoting properties in the food and pharmaceutical industries. [2][3][4] In this context, olive oil sector generates every year huge amounts of wastes such as olive tree pruning, olive leaves or exhausted olive pomace that must be properly managed. Currently, their applications are still scarce although their lignocellulosic nature makes them interesting raw materials for biorefinery processes but also their non-structural fraction can be exploited. [5][6][7] Furthermore, the valorization of these residues through bioconversion processes would also contribute to the development of the circular economy model in the rural areas where they are generated. [8] Exhausted olive pomace (EOP) is the final residue after extracting with hexane the oil that remains in the olive pomace. Like olive pomace, EOP contains fragments of olive skin, pulp, and stone but its oil content is lower than 2% and its moisture is also much lower than olive pomace, about 10%. [9] EOP is the main residue generated in the olive pomace extracting industry and its main application is as fuel in the same industries where it is generated. The presence of stones in the composition of EOP contributes to its high calorific value (about 3755 kcal kg −1 ). Nevertheless, the amount of stones in EOP is variable and depends on the upstream depitting because the stones are removed from olive paste in the mills and/ or from olive pomace in the extracting industries. [10] In addition, organic compounds highly polluting have been identified in the gas emissions generated during the combustion of this waste. [11] Therefore, EOP could be considered residual biomass with great potential for the production of bioactive ingredients, such as the phenolic compound hydroxytyrosol, which has been reported as a compound with antioxidant, chemopreventive and anti-inflammatory properties. [9] The olive pomace oil extracting industry generates large amounts of exhausted olive pomace (EOP), a lignocellulosic waste that needs to be managed according to sustainable criteria. The aim of this work is to devise an integrated strategy to valorize EOP by applying two-step extraction, and to evaluate the effect of an ethanol organosolv pretreatment on the delignification and enzymatic hydrolysis of the extracted EOP. Once the extraction and organosolv pretreatment conditions are selected, solubilized lignin is recovered from the pretreatment liquor using different methods. In addition to those organosolv lignin samples, a lignin-rich solid is obtained after enzymatic ...