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

Abstract

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 ...

Hepatopreventive properties of hydroxytyrosol and mannitol-rich extracts obtained from exhausted olive pomace using green extraction methods

“…to also obtain sugars and valuable sugar derivatives like bioethanol, antioxidant lignin, etc . 67,68…”

“…to also obtain sugars and valuable sugar derivatives like bioethanol, antioxidant lignin, etc. 67,68 According to the aforementioned calculation, 64 the extrapolated dose of CCl 4 could be related to an exposition of ∼4.9 mL for an adult of 60 kg. This chemical is rarely used today, but it still has applications in some industries.…”

Organosolv pretreatment: an in-depth purview of mechanics of the system

“…Ferreira and Taherzadeh ( 2020 ) stated that the usage of ethanol has been reinforced by paradigm shift tactics with the incorporation of first/second-generation bioethanol for promoting the commercialization of cellulosic ethanol. Gómez-Cruz et al ( 2022 ) used exhausted olive pomace and used a two-stage extraction process to determine the influence of ethanol-oriented organosolv-assisted pretreatment on its delignification and hydrolysis. Among the various systems, ethanol (50%) catalyzed with sulphuric acid (1%) at 140 °C for 60 min with biomass (15%) enabled efficient enzymatic digestibility (81%) along with the attainment of high grade of organosolv (dissolved) lignin (71%) that were superior of guaiacyl units.…”