Search Results (227)

Rice straw is a highly produced agricultural waste with a high cellulose content, which can be used as a cellulose source. Nevertheless, more sustainable extraction and purification strategies are needed to reduce the consumption of chemicals during the production of cellulose-derived materials. In this way, an integrated method based on subcritical water extraction and bleaching with hydrogen peroxide was used for isolating cellulose from rice straw. The cellulose fibres obtained were converted into microcrystalline cellulose (MCC) by applying acid hydrolysis with HCl 2N at 60 °C to reduce the fibre amorphous fraction. High cellulose purity (86%) and crystallinity (67%) were obtained in the isolated fibres. The influence of high-shear homogenisation (12,000 rpm) during hydrolysis was analysed, compared to mild stirring (350 rpm) at different times (30 and 60 min). High-shear homogenisation greatly accelerated the hydrolysis process of the amorphous fraction of the fibres, contributing to the reduction in particle size (to about 10 µm), defibration, increased crystallinity (70–72%), and shorter cellulose chains (92,400–61,600 g/mol) for a given treatment time. After 30–60 min of treatment, the resulting MCCs exhibited properties within the range reported for commercial AVICEL, with greater reinforcing performance in PHBV films. These MCCs resulted in lower water vapour permeability, while improved oxygen barrier properties were mainly observed for those obtained under high-shear hydrolysis conditions. Full article

Subcritical water extraction (SWE) is an eco-friendly and efficient technique for isolating bioactive ingredients from natural products. To improve the extraction yield of Artemisia argyi leaf polysaccharides (AAPs), a three-stage hybrid optimization strategy combining single-factor experiments, response surface methodology (RSM), neural network (NN), and direct search algorithm (DSA) was proposed. Single-factor experiments were used to screen key parameters. A Box–Behnken design (BBD)-based RSM was applied for preliminary optimization. A {3, 5, 1} structured NN was trained using 63 datasets from RSM, and DSA was used to determine the globally optimal process parameters. The optimal conditions were obtained as follows: extraction time 17.72 min, liquid-to-solid ratio 92.83 mL/g, extraction temperature 123.35 °C, stirring speed 1800 r/min, and natural pH. Under these conditions, the experimental AAP extraction yield reached 6.99%, with a relative error of only 1.16% compared with the predicted value of 6.91%. Fourier transform infrared (FT-IR) spectroscopy confirmed that the product exhibited typical polysaccharide structural characteristics. The integrated RSM–NN–DSA framework provides a reliable and high-precision approach for optimizing SWE of plant polysaccharides, showing good potential for industrial applications. Full article

Globe artichoke (Cynara scolymus) processing generates large amounts of agro-industrial waste, including stems, leaves, and bracts. These by-products represent a valuable and underexplored source of bioactive compounds, particularly phenolic acids, flavonoids, pectin, and inulin, which exhibit significant nutritional, health-promoting, and functional properties. This review provides a comprehensive overview of green extraction strategies applied to the recovery of bioactive compounds from globe artichoke waste, with emphasis on green extraction techniques such as deep eutectic solvent, ultrasound-assisted, microwave-assisted, enzyme-assisted, subcritical water, supercritical CO₂, and the use of green solvents. Nutritional composition and biological activities, including antioxidant, antimicrobial, anti-inflammatory, hypolipidemic, and hepatoprotective effects of artichoke waste extracts, are critically discussed. Given the inherent instability and limited bioavailability of many phenolic compounds, recent advances in encapsulation and stabilisation approaches, alginate-based systems, spray-drying, and nano and microencapsulation technologies are highlighted as effective strategies to enhance shelf life and controlled release. The valorisation of globe artichoke waste through green extraction and encapsulation of bioactive compounds contributes to circular economy principles by reducing environmental impact while adding value. Overall, the promising role of artichoke by-products as sustainable resources for functional food development is discussed. Full article

Annatto (Bixa orellana L.) seed by-products (ASBs), generated after industrial pigment extraction, remain a largely underexplored source of bioactive compounds, including residual carotenoids, phenolics, and proteins. This study compares three extraction strategies—maceration (ME), ultrasound-assisted extraction (UAE), and subcritical water extraction (SWE)—for the recovery of these compounds from ASB within a green processing framework. Extraction efficiency was assessed based on the yield, protein recovery, total carotenoid content (TCC), total phenolic content (TPC), antioxidant capacity (DPPH, ABTS, FRAP), and phenolic profile (HPLC-DAD). SWE at 140 °C (40 bar, 1:30 g/mL) achieved the highest extraction yields and compound recovery (proteins: 80.0 ± 3.22 mg/g extract; TCC expressed as bixin equivalents: 1.60 ± 0.07 mg/g extract; TPC: 17.96 ± 0.90 mg GAE/g extract). Phenolic profiling identified gallic and protocatechuic acids as major constituents, with significantly higher concentrations in SWE extracts. However, discrepancies between spectrophotometric and chromatographic data suggest the presence of unidentified phenolics. Cytotoxicity assays using Caco-2 cells indicated no significant effects at concentrations up to 10 µg/mL. While SWE demonstrates superior extraction performance, further studies on protein functionality, pigment stability, and bioavailability are required to validate food and nutraceutical applications. This work highlights ASB as a promising resource for circular bioeconomy strategies. Full article

In the context of the circular economy, the valorization of natural biomolecules from by-products has recently represented a major goal in health promotion. From this perspective, this study examined the antioxidant potential of Sicilian white grape pomace from the Pinot Gris variety, using subcritical water extraction as an eco-friendly and innovative method to recover bioactive compounds. Different extraction parameters allowed for comparing the potential of various fractions. Among these, the Subcritical Water Extract obtained after 5 min at 160 °C (SWE^160.1) was rich in gallic acid and protocatechuic acid, as evidenced by characterization with UHPLC-Q Exactive Orbitrap-HRMS system. SWE^160.1 showed efficacious antioxidant activity, as confirmed by DPPH assay and total polyphenol and flavonoid content. Interestingly, SWE^160.1 displayed cytotoxic activity in tumor cell lines, while preserving the viability of non-tumor bronchial epithelial cells. Specifically, SWE^160.1 protected these cells from exogenous oxidative stress, reducing the ROS levels and activating Nrf2-mediated antioxidant response. Surprisingly, upregulation of antioxidant enzymes (HO-1 and SOD-2) induced by SWE^160.1 was maintained in the presence of lipopolysaccharide, indicating a specific involvement of SWE^160.1 in the anti-inflammatory response. Finally, SWE^160.1 was also able to limit the formation of stress granules following acute stress, thereby supporting its potential to maintain cellular homeostasis. Overall, this study highlights the potential of grape pomace as a source of active molecules to prevent oxidative stress and inflammation. Full article

Grape pomace, the main solid by-product of winemaking, is a promising feedstock for the recovery of trans-resveratrol, a high-value stilbene of increasing interest for food, nutraceutical, and pharmaceutical applications. However, its efficient isolation remains challenging because of matrix complexity, the co-occurrence of structurally related stilbenes and polyphenols, and the chemical instability of trans-resveratrol. This review critically examines recent advances in the recovery of trans-resveratrol from grape pomace, while also incorporating relevant findings from other grapevine-derived matrices to distinguish matrix-specific recovery potential and to place grape pomace within the broader context of grapevine by-product valorization from extraction intensification and selective purification to analytical determination. Various extraction technologies, including ultrasound-, microwave-, and enzyme-assisted extraction, natural deep eutectic solvents, and subcritical water extraction, are assessed alongside conventional solvent extraction with emphasis on yield, selectivity, solvent compatibility, and process feasibility. Downstream separation methods such as liquid–liquid partitioning, solid-phase isolation, adsorbent resins, counter-current chromatography, molecularly imprinted polymers, and foam fractionation are compared in terms of selectivity, enrichment efficiency, solvent demand, and scale-up potential. Although significant progress has been achieved, major challenges remain regarding process integration, solvent sustainability, product stability, and industrial feasibility. Combining mild extraction with selective downstream purification is essential for producing stable, high-purity trans-resveratrol fractions suitable for future use in functional ingredients, natural preservation strategies, and other value-added applications within sustainable food systems. Full article

The increasing global demand for natural bioactive compounds in the food, nutraceutical, and pharmaceutical sectors highlights the need for sustainable extraction technologies capable not only of efficiently valorizing crop biomass and agro-waste but also of producing reproducible and standardized botanical extracts. Subcritical water extraction (SWE), which utilizes pressurized hot water at temperatures between 100 °C and 374 °C to modify solvent properties, has emerged as a promising green alternative to conventional organic solvent-based extraction methods. Despite its advantages in terms of environmental compatibility, extraction efficiency and tunable selectivity, the industrial application of SWE remains limited, and strategies for obtaining standardized extracts using this technology are still insufficiently explored. This review provides a comprehensive overview of SWE in the context of natural product extraction and the development of standardized plant extracts. The fundamental principles of SWE are discussed, including temperature-dependent changes in water polarity, solvent–solute interactions, and the influence of key process parameters such as temperature, pressure, extraction time, and particle size. Particular emphasis is placed on how these factors affect extraction selectivity, phytochemical composition, and reproducibility, which are critical aspects for extract standardization. Mechanistic insights into plant cell disruption, compound stability, and hydrothermal transformations under SWE conditions are also examined. Recent applications of SWE for the extraction of phenolics, flavonoids, terpenoids, alkaloids, and other pharmacologically relevant compounds are reviewed, highlighting the relationship between extraction conditions and extract quality. Finally, current challenges and future perspectives for integrating SWE into the production of standardized botanical extracts suitable for food, nutraceutical, and pharmaceutical applications are discussed, paving the way for the wider industrial adoption of this environmentally friendly technology. Full article

Despite its rich bioactive composition, orange peel dust (OPD), a fine industrial by-product generated during citrus processing in the filter tea industry, has not received much attention as a valuable matrix. Using antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and reducing power (RP)), α-amylase inhibitory activity, antimicrobial potential, and sugar composition as function-oriented indicators, this study aimed to compare four green extraction technologies: subcritical water extraction (SWE), pressurized ethanol extraction (PEE), ultrasound-assisted extraction (UAE), and sequential supercritical CO₂–UAE (Sc-CO₂–UAE) applied to OPD derived from Citrus sinensis L. Among thermally driven techniques, PEE at 220 °C had the highest radical-scavenging activity, while UAE showed the broadest antifungal activity against Fusarium spp. and Alternaria alternata, along with selective antibacterial activity against Bacillus cereus. Sequential Sc-CO₂ pretreatment at 300 bar followed by UAE resulted in the highest α-amylase inhibitory activity. Sugar analysis indicated that thermal conditions enhanced carbohydrate hydrolysis, while UAE and Sc-CO₂-UAE maintained structural sugars under mild conditions. All green extraction approaches outperformed conventional maceration. These findings validate OPD as a valuable industrial by-product suitable for sustainable valorization, supporting circular economy concepts in the citrus processing sector. Full article

Agroindustrial residues represent an abundant and underutilized source of carbon-rich materials for environmental remediation. In this study, annatto processing waste (Bixa orellana), a largely unexplored lignocellulosic by-product generated during pigment extraction, was converted into hydrochar via hydrothermal carbonization at 200 °C for 3 h. The resulting hydrochar (HC-AW) exhibited a predominantly amorphous carbon structure with retained oxygen-containing surface functionalities, and a solid yield of 44%, indicating efficient biomass conversion under subcritical conditions. Adsorption performance toward tetracycline was evaluated through pH-dependent experiments, kinetic modeling, equilibrium isotherms, and thermodynamic analysis. Maximum adsorption occurred under near-neutral conditions (pH ≈ 7), consistent with the interplay between tetracycline speciation and the hydrochar surface charge (pH_PZC ≈ 6.3), highlighting its potential applicability under realistic water treatment conditions without pH adjustment. Kinetic data were well described by the pseudo-second-order model, while equilibrium results were best fitted by the Langmuir model, with a maximum adsorption capacity of 14.94 mg g⁻¹ at 30 °C. Thermodynamic analysis indicated a spontaneous and slightly endothermic adsorption process. Overall, the results highlight the potential of annatto-derived hydrochar as a low-cost adsorbent and provide insight into the relationship between surface properties and adsorption behavior governing antibiotic removal from aqueous systems. Full article

The rising demand for sustainable and circular approaches in the agro-industrial sector has generated interest in repurposing herbal tea residues as sources of high-value bioactive compounds. This work focusses on recovering phytochemicals from Rosa canina L. peel and seed dust (by-products of processing of herbal tea in filter tea bags) using green extraction techniques. Two environmentally friendly technologies were used: ultrasound-assisted extraction (UAE) with a sonotrode and subcritical fluid extraction (SBFE). The extracts were qualitatively profiled using (HR) LC-ESI-QToF-MS/MS and quantified using HPLC-PDA. Both by-products contained phenolic substances, including gallic acid derivatives, ellagic acid, and flavonoids such as quercetin and quercetin-3-O-glucoside (only in the peel). Additionally, Folin–Ciocalteu’s assay was used to determine Total Phenolic content (TP). The extraction efficiency was considered in terms of phenolic compound recovery and total phenolic content obtained under the respective experimental conditions. The maximum TP for SBFE was reported in samples extracted with ethanol–water (48:52) at 180 °C, producing 3876.67 GAE mg/L for peel and 1648.57 GAE mg/L for seeds. In the UAE, extraction with ethanol–water (48:52) for 10 min yielded the maximum TP of 2773.81 GAE mg/L for peel and 957.86 GAE mg/L for seeds. These findings highlight the potential of R. canina infusion by-products as long-term sources of bioactive compounds for use in nutraceutical, cosmetic, and pharmaceutical industries. Full article

An electrical heating fluidized-bed thermal energy storage (EH-FB-TES) system is proposed for integration with a coal-fired power plant (CFPP) for deep peak shaving (DPS) due to its high energy storage density and extensive heat exchange performance. The primary objective of this study is to evaluate the thermodynamic performance and economic feasibility of the integrated EH-FB-TES system, specifically focusing on identifying the optimal coupling and heat recovery strategies for enhanced deep peak shaving performance. Since EH-FB-TES uses air flow for fluidization in the heating storage process, its coupling with the CFPP differs from other TES technologies, and the associated thermodynamic performance and cost are thereby analyzed. The results show that, in EH-FB-TES, the heat release efficiency is predominantly constrained by thermal losses. To increase the energy utilization efficiency, a two-stage heat recovery strategy is proposed to release the stored energy in the integration. The first stage is to heat up the feedwater extracted from the deaerator and the second one is to heat up the condensate water. The analyses also show that the selection of reinjection positions for the heated medium from EH-FB-TES greatly influences the system performance. Returning the stored thermal energy to heat up feedwater can effectively increase the output of the unit, while directly generating steam can be beneficial for coal saving. The integrated system achieves a maximum equivalent round-trip efficiency of 32.9% under 20 MW/800 °C conditions. An economic analysis reveals that, compared with other energy storage methods, EH-FB-TES can realize a relatively high energy storage density with a rather low cost. Under the present DPS compensation policy, for a 315 MW subcritical CFPP integrated with a 50 MW EH-FB-TES system, when heat storage is 8 h, heat release is 4 h per day, and the plant operates 100 days per year, the estimated static and dynamic payback periods are 3.06 years and 3.67 years, respectively. The integration of CFPP with EH-FB-TES could be promising for meeting DSP requirements. Full article

Pomegranate marc is a major, underutilized juice industry by-product rich in lipophilic polyunsaturated fatty acids—notably conjugated α-linolenic acids (CLnAs)—and hydrophilic polyphenols with potent antioxidant and anti-inflammatory properties. Despite its potential for nutraceutical, cosmetic, and pharmaceutical applications, this matrix remains largely unexploited. This study presents a novel, sequential in-line extraction strategy combining supercritical CO₂ (ScCO₂) and subcritical water (scW) to recover complementary bioactive fractions. Both extraction steps were optimized via Response Surface Methodology (RSM). Box–Behnken optimization of ScCO₂ (43 MPa, 76 °C, 6.4 L min⁻¹, 124 min) yielded 30 g kg⁻¹ dry weight (dw) of oleoresin, achieving a 68% recovery of total oil. Subsequent scW extraction was optimized at 149 °C, with a 40 L kg⁻¹ water-to-solute ratio and 73 min extraction time, yielding 47 g kg⁻¹ dw of total phenolics (58% recovery). Strong agreement between experimental and predicted values confirmed the robustness of the models. Comprehensive profiling revealed a diverse phytocomplex including fatty acids, tocopherols, flavonoids, soluble sugars, and polysaccharides. Antioxidant assays confirmed that both γ-tocopherol and polyphenols significantly contribute to the extracts’ bioactivity. To improve physical handling, the aqueous fractions were converted into solid dispersions via spray drying with maltodextrin. Preliminary in vitro biological assessments on HEK-293 (human embryonic kidney) and MCF-7 (Michigan Cancer Foundation-7) cell lines suggested that the maltodextrin-based formulations may modulate the cytotoxic profile compared to the free extract, with exploratory results showing dosage-dependent variations in cell viability across the two lines. This work suggests a potentially scalable and sustainable biorefinery approach for the integral valorisation of pomegranate marc, offering a basis for a pathway to produce solvent-free bioactives. Full article

Olive pomace, a byproduct of olive oil production, is a rich source of bioactive phenolic compounds with potential health benefits. This study aimed to characterize the chemical composition and evaluate the metabolic effects of a subcritical water extract from California olive pomace (SWE COP) obtained from Arbequina olives. The extract was mainly composed of carbohydrates (72.81%) and contained 66.62 ± 1.22 mg gallic acid equivalents/g of phenolics, with 3,4-DHPEA-EDA, hydroxytyrosol, and verbascoside identified as the predominant compounds. Male C57BL/6N mice were fed a standard diet (SD; n = 7), a high-fat and high-sugar diet (HFSD; n = 7), which was used to induce features of diet-associated metabolic syndrome, or an HFSD supplemented with 3% (w/w) SWE COP (n = 7) for 16 weeks. Supplementation with SWE COP significantly reduced plasma triglycerides and increased HDL cholesterol levels compared with the HFSD group. Moreover, SWE COP improved glucose tolerance, enhanced insulin sensitivity, and reduced mesenteric and epididymal adiposity. Histological analysis showed that SWE COP alleviated hepatic steatosis and lowered the NAFLD activity score. These findings demonstrate that phenolic-rich SWE COP exerts beneficial effects on glucose and lipid metabolism and reduces liver fat accumulation in diet-induced obese mice. Overall, SWE COP represents a promising functional ingredient derived from olive industry byproducts for mitigating metabolic dysfunctions associated with obesity. Full article

Biopolymers from renewable sources are increasingly explored to reduce the carbon footprint of materials and mitigate plastic pollution. This review synthesizes the last five years of progress across the biopolymer value chain, comparing plant, microbial/fermentation, fungal, and marine/algal resources and critically assessing greener extraction and fractionation routes (ultrasound and microwave intensification, subcritical water, supercritical CO₂ with co-solvents, ionic liquids, deep eutectic solvents including natural deep eutectic solvents, and enzymatic or bio-mediated processes). We emphasize yield-selectivity trade-offs, scalability, energy demand, and solvent recovery. Downstream, we summarize purification and performance tuning via crosslinking, derivatization, blending/plasticization, and nanocomposites, and we map advanced characterization to targeted functional properties to bridge processing choices with end-use performance. Applications are organized across food and agriculture, biomedical and pharmaceutical technologies, packaging, and cosmetics, with cross-cutting attention to safety and regulatory compliance, quality-by-design, techno-economics, and life-cycle assessment. Key bottlenecks are feedstock variability, viscosity and recyclability limitations of designer solvents, and persistent gaps in barrier and thermal properties versus petrochemical benchmarks, compounded by uneven composting and recycling infrastructure. Promising directions include low-viscosity or switchable solvents, data- and artificial intelligence (AI)-guided process optimization, engineered biopolymers, and circular end-of-life strategies that align material design with realistic recovery routes. Full article

This study proposes a sustainable strategy to valorise strawberry lignocellulosic agro-industrial byproducts through the recovery of antioxidant and antimicrobial compounds (AOM) for use in active edible coatings. Subcritical water extraction (SWE), optimised using response surface methodology, was applied to maximise phenolic content and antioxidant capacity while minimising sugars’ co-extraction. Optimal SWE conditions (120 °C, 5 min, and S/L ratio 40) yielded a total phenolic content (TPC) of 146.9 mg GAE/g DM and an antioxidant activity of 24.8 mg TE/g DM, comparable to ethanolic reflux extraction (138.4 mg GAE/g DM and 23.4 mg TE/g DM). Scale-up in a Parr pressurised reactor achieved 91.2% polyphenol recovery relative to accelerated solvent extraction (ASE). Purification using Amberlite^® XAD 7 resin enhanced TPC purity and antioxidant activity more than 2.5-fold, producing a desorbed fraction with a polyphenol purity of 93.9% (w/w, dry basis) and no detectable sugars. The purified AOM was incorporated (1% w/v) into a 1.5% (w) chitosan solution obtained from Hermetia illucens pupal exuviae to produce a biopolymeric active coating. Application to strawberries was associated with a reduction in fungal infection severity (−72%) and incidence (−66.7%) under natural infection conditions. Although fruit firmness declined during storage, coated samples showed significantly better firmness retention. These results demonstrate the effectiveness of combining chitosan with phenolic extracts obtained by SWE to enhance microbial stability and maintain fruit quality. Full article