Sequential extraction of almond hull biomass with pulsed electric fields (PEF) and supercritical CO2 for the recovery of lipids, carbohydrates and antioxidants

This work reports the first example of combined sequential extraction by pulsed electric fields (PEF) (3 kV/cm, 100 kJ/kg, 2 Hz, 100 ms) and supercritical (SC) fluid extraction (SFE) (15 MPa, 25 mL/min, 50ºC, 60 min) with CO2 (SC-CO2) for the valorisation of almond hull (AH) biomass. PEF+SFE boosted the efficiency of the protocol up to 77% for total antioxidant capacity and 20% in terms of polyphenols recovery compared to the traditional soaking. Triple-TOF-LC-MS-MS analysis provided the phenolic profiles for the PEF and SC-CO2 extracts, observing significant differences in the polyphenol profile according to the technology applied. Additionally, NMR analysis detected the presence of the carbohydrate soluble (mainly glucose, fructose and sucrose) and lipidic fractions, both selectively extracted by PEF or SC-CO2, respectively. Finally, the post-extraction residual solid biomass was characterized by several techniques such as TGA, FT-IR and SEM. For the latter, the formation of surface pores after PEF and a high fibre compaction after SFE was observed. On the other hand, DTG curves allowed to firmly propose concurrent valorisation routes for this solid, in agreement with a zero-waste approach

Valorization of wastewater from table olives: NMR identification of antioxidant phenolic fraction and microwave single-phase reaction of sugary fraction

The table olive industry is producing a huge amount of wastewater, which is a post-processing cost and an environmental concern. The present study aims to valorize this processing by-product to obtain a value-added product, thereby enhancing resource efficiency and contributing to achieving sustainable development goals (SDGs). In this sense, a chemical reaction-based platform was developed to obtain valuable components, such as levulinic acid (LA) and 5-hydromethylfurfural (HMF). The products were then analyzed using NMR identification of the antioxidant phenolic fraction and microwave single-phase reaction of the sugary fraction. According to the results, the highest concentration of phenolic compounds does not correspond to the sample directly obtained from NaOH treatment (S1), indicating that water washing steps (S2-S5) are fundamental to recover phenolic substances. Moreover, glucose was presented in the sugary fraction that can be transformed into levulinic acid by a single-phase reaction under microwave irradiation. The information provided in this manuscript suggests that the wastewater from the olive processing industry can be valorized to obtain valuable products

Table olive wastewater as a potential source of biophenols for valorization : a mini review

The table olive industry generates high amounts of wastewater annually during the alkaline treatment, fermentation, and washing steps of olives. High conductivity and salt content, as well as the high organic and biophenol contents of these waters, is a worldwide problem, especially in the Mediterranean region, which is the major table olive producing area. There is a wide variety of bioactives found in wastewater derived from table olive processing. The main compounds of table olive wastewater, such as those derived from phenolic, hydrocarbon, and sugar fractions, can be recovered and reused. In this review, the table olive manufacturing processes and the volumes and composition of wastewater generated from the different methods of table olive processing are discussed. In addition, biophenols of table olive water and their biological activities are also introduced. The high concentrations of valuable biophenols, such as tyrosol and hydroxytyrosol, show promising potential for valorizing table olive wastewater; however, more research is needed in this area

A preliminary multistep combination of pulsed electric fields and supercritical fluid extraction to recover bioactive glycosylated and lipidic compounds from exhausted grape marc

This article reports the first multistep combination of pulsed electric field (PEF; 3 kV/cm, 100 kJ/kg, 2 Hz, 100 ms) and supercritical fluid extraction (SFE) with CO2 (10-20 MPa, 25 mL/min [10% EtOH], 50 °C, 60 min) for exhausted grape marc (EGM). This current protocol was mainly created to recover bioactive glycosylated and lipidic compounds. In this regard, total antioxidant capacity (TAC) was enhanced up to 68% after PEF treatment compared to conventional soaking. However, re-extracting PEF-treated EGM after the application of SFE (PEF + SFE) boosted the efficiency by up to 87%. Several polyphenols (kaempferol, luteolin, scutellarin, and resveratrol, among others), together with other glycosylated structures, were identified by liquid chromatography coupled with mass spectrometry analysis. The bioactive lipidic compounds extracted by SFE, along with the carbohydrate fraction (free sugars) favourably extracted by PEF pre-treatment (mainly glucose, but also fructose and sucrose), were concurrently detected by nuclear magnetic resonance. The remaining solid fraction after treatment was also characterised. Different microscopic morphology was observed by scanning electron microscopy (SEM) on untreated, PEF, and PEF + SC-CO2-treated EGM. Differential thermogravimetric (DTG) curves determined by thermogravimetric analysis (TGA) also suggested alternative and potential means for the valorisation of this matrix

Sustainable production of solid biofuels and biomaterials by microwave-assisted, hydrothermal carbonization (MA-HTC) of Brewers' Spent Grain (BSG)

7 figures, 2 tables.-- This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry and Engineering, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acssuschemeng.0c06853This work addresses the management of Brewers’ Spent Grain (BSG) using a state-of-the-art, microwave-assisted, hydrothermal carbonization (MA-HTC) process, for the production of hydrochar, i.e., a renewable solid biomaterial with many industrial applications. For the first time, a detailed relationship has been established between the processing conditions and the properties of the hydrochar via a thorough physicochemical characterization. The experimental results revealed that the temperature (180–250 °C) and reaction time (0–2 h) used in the MA-HTC process exerted a significant influence on the yield and properties of the hydrochar. An increase in these variables (process severity) diminished the hydrochar yield. However, such increments were beneficial to enhance the fuel properties of this product, as the proportions of O and C decreased and increased, respectively. As a result, this process was capable of transforming up to 47% of the original BSG into a high-energy hydrochar with a calorific value of 32 MJ/kg. The characterization of the hydrochar revelated that it was a mesoporous, hydrophilic, rough material, containing several cavities and oxygen functionalities on the surface. These features not only provide the hydrochar with a high aromatic character but also are fundamental for its potential applicability as a bioadsorbent material. An increase in the MA-HTC severity augmented the amounts of aliphatic and aromatic structures in the hydrochar as well as the roughness and the presence of cavities, thus highlighting the excellent flexibility of the process. Therefore, these promising results, together with the energy-efficient and bespoke nature of the MA-HTC process, which substantially reduces the reaction temperature and processing times in comparison to standard carbonization procedures reported to date, represent a step-change not only for the production of biofuels and biomaterials but also for the management of BSG.Consejería de Educación, Cultura y Deporte of Junta de Comunidades de Castilla-La Mancha (Spain) and Ministerio de Ciencia Innovación y Universidades provided financial funding for this work via the projects SBPLY/17/180501/000522 and RTI2018–099503-B-100, respectively; both being co-financed by the Fondo Europeo de Desarrollo Regional (FEDER). Besides, the Industrial Biotechnology Catalyst (Innovate UK, BBSRC, EPSRC) and Biotechnology processes (EP/N013522/1) have also contributed. EPSRC for research grant number EP/K014773/1. In addition, A.L. would like to express her gratitude to the University of Castilla-La Mancha for her predoctoral fellowship (2014/10340) and financial grant to conduct international research (2016/11635) granted. At the same time, J.R. is very grateful to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva fellowships (FJCI-2016-30847 and IJC2018-037110-I) awarded.Peer reviewe