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- Salgado-Ramos, Manuel, et al.
(författare)
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A preliminary multistep combination of pulsed electric fields and supercritical fluid extraction to recover bioactive glycosylated and lipidic compounds from exhausted grape marc
- 2023
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Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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2. |
- Salgado-Ramos, Manuel, et al.
(författare)
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Microwave heating for sustainable valorization of almond hull towards high-added-value chemicals
- 2022
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Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Microwave (MW) treatment promotes homogeneous heating compared to conventional methods, thus increasing the recovery of high-added-value compounds and leading to a considerably lower amount of both by-products and side reactions. Therefore, the main goal of this work is to valorize almond hull (AH) via microwave (MW)-assisted radiation (0–200 W, 0–300 psi, 100–190 °C, 10–40 min). In this context, two different pathways were evaluated. Firstly, the transformation of AH into levulinic acid (LA), one of the major bio-based chemicals obtained from lignocellulosic biomass. The so-called almond hull extractives-free biomass (AH-EFB) led to the best results after using both Lewis (AlCl3⋅6 H2O, 1 mol/L, 87 % molar yield) and Brønsted (p-toluenesulfonic (p-TsOH), 0.25 mol/L, 91 % molar yield) acids, at 190 °C for 20 min. This latter not only provides a sustainable system in contrast to mineral acids such as H2SO4 or HCl, but also the possibility of being recovered and recycled for further transformations. In a parallel secondary experiment, the recovery of biologically active compounds (BACs) was studied separately. For this purpose, antioxidant assays and phenolic profiling were carried out, which demonstrated that MW was more efficient than traditional methods (i.e. soaking) based on obtained values in terms of scavenging activity and polyphenols. Overall, this valorization approach involves most of the Green Chemistry principles, thus contributing to the development of almond biorefineries.
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3. |
- Salgado-Ramos, Manuel, et al.
(författare)
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Sequential extraction of almond hull biomass with pulsed electric fields (PEF) and supercritical CO2 for the recovery of lipids, carbohydrates and antioxidants
- 2023
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Ingår i: Food and Bioproducts Processing. - 0960-3085 .- 1744-3571. ; 139, s. 216-226
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Tidskriftsartikel (refereegranskat)abstract
- 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, 50 degrees C, 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 SCCO2 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.
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