Multiproduct biorefinery based on almond shells: Impact of the delignification stage on the manufacture of valuable products

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 ...

show abstract

“…Thus, signals at 1721 cm,1427, 1186–1160, and 1030 cm –1 can also be attributed to hemicellulose and cellulose. [ 53,54 ]…”

Section: Resultsmentioning

confidence: 99%

“…Thus, signals at 1721 cm,1427, 1186-1160, and 1030 cm -1 can also be attributed to hemicellulose and cellulose. [53,54] The functional groups of the different lignin samples were determined by 13 C-NMR analysis. A comparison between the different spectra obtained for each sample is shown in…”

Section: Chemical Characterization By Py-gc-msmentioning

confidence: 99%

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

Gómez‐Cruz

Romero

Contreras

et al. 2022

Advanced Sustainable Systems

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, peaks at 1603, 1424, 1114, and 1026 cm −1 were indicative of the existence of carbohydrate-derived compounds. 28 The chemical composition of biopolyols was determined by GC-MS, whose chromatograms are shown in Figure 2. For a better understanding, the chromatograms were delimited in three zones, namely, a, b, and c. The first zone a corresponded to carbohydrate degradation compounds, which confirmed the presence of these compounds in both samples, as mentioned in the previous section.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Renewable Biopolyols from Residual Aqueous Phase Resulting after Lignin Precipitation

Hernández‐Ramos

Alriols

Calvo‐Correas

et al. 2021

ACS Sustainable Chem. Eng.

Self Cite

View full text Add to dashboard Cite

The aim of this work was to obtain two biopolyols from the liquid residue resulting from the precipitation of lignin contained in two different black liquors, Eucalyptus globulus organosolv black liquor (EOBL) and Pinus radiata organosolv black liquor (POBL), thus adding value to this residue. Eucalyptus organosolv polyol (EOP) and Pine organosolv polyol (POP) were characterized to know their viscosity, hydroxyl number (I OH), and functionality according to the corresponding standard American Society for Testing Materials (ASTM). The molecular weight of the biopolyols was measured through gel permeation chromatography (GPC); the chemical structure and composition were characterized by Fourier transform infrared (FTIR) and gas chromatography–mass spectrometry (GC-MS), respectively; and the thermal degradation (TGA) of the two biopolyols was determined. The biopolyols showed suitable properties to be employed in the production of polyurethanes (PU).

show abstract

“…Compared to conventional methods, it allows the extraction of higher yields of bioactive compounds, thus resulting on a tocopherol-enriched and/or polyphenol-enriched almond oil. Moreover, the use of CO 2 as a solvent in the supercritical extraction of almond oil has several advantages over conventional solid-liquid extractions, namely avoiding the use of harmful and toxic organic solvent, not needing to refine the obtained oil, and the higher yield obtained by this method [52,53,75]. Therefore, in the last years, SFE is attracting the industry's attention as consumers are increasingly interested in products obtained with cleaner technologies as an alternative to the employment of organic solvents.…”

Section: Supercritical Fluid-assisted Extractionmentioning

confidence: 99%

“…Souza et al (2020) [81] evaluated the effect of EAE on the recovered oil and protein from almond cake and concluded that it enabled a similar extractability while resulting in a creamy fraction easier to be demulsified (corresponding to an oil recovery of 99%), together with a skim fraction rich in proteins with lower surface hydrophobicity and higher solubility at lower pH, which can be particularly important for applications in acidic media. Morales et al (2020) [53] proposed the integral valorization of ASHs through a biorefinery approach in which enzymatic hydrolysis was used to obtain glucose and generate solids rich in lignin and cellulose. In other work, Singh et al (2019) [26] reported the application of EAE to almond bark for recovering low-degree polymerized xylooligosaccharides.…”

Section: Enzyme-assisted Extractionmentioning

confidence: 99%

Revalorization of Almond By-Products for the Design of Novel Functional Foods: An Updated Review

García-Pérez

Xiao

Munekata³

et al. 2021

Foods

View full text Add to dashboard Cite

The search for waste minimization and the valorization of by-products are key to good management and improved sustainability in the food industry. The great production of almonds, based on their high nutritional value as food, especially almond kernels, generates tons of waste yearly. The remaining parts (skin, shell, hulls, etc.) are still little explored, even though they have been used as fuel by burning or as livestock feed. The interest in these by-products has been increasing, as they possess beneficial properties, caused by the presence of different bioactive compounds, and can be used as promising sources of new ingredients for the food, cosmetic and pharmaceutical industry. Additionally, the use of almond by-products is being increasingly applied for the fortification of already-existing food products, but there are some limitations, including the presence of allergens and mycotoxins that harden their applicability. This review focuses on the extraction technologies applied to the valorization of almond by-products for the development of new value-added products that would contribute to the reduction of environmental impact and an improvement in the sustainability and competitiveness of the almond industry.

show abstract

Multiproduct biorefinery based on almond shells: Impact of the delignification stage on the manufacture of valuable products

Cited by 34 publications

References 45 publications

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

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

Renewable Biopolyols from Residual Aqueous Phase Resulting after Lignin Precipitation

Revalorization of Almond By-Products for the Design of Novel Functional Foods: An Updated Review

Contact Info

Product

Resources

About