Search Results (1,495)

Food industry generates substantial waste, raising economic and environmental concerns. Green Chemistry (GC) highlights the extraction of nutritional and bioactive compounds as a key strategy for waste valorization, driving interest in sustainable methods to recover valuable compounds efficiently. This review evaluates the sustainability of widely used emerging extraction technologies—Microwave-, Ultrasound- and Enzyme-Assisted, as well as Supercritical Fluid Extraction—and their alignment with GC principles for agri-food waste valorization. It first outlines the principles, key parameters, and main advantages and limitations of each technique. Subsequently, sustainability is then assessed in selected studies using the Analytical GREEnness Metric Approach (AGREEprep). By calculating the greenness score (GS), this metric quantifies the adherence of extraction processes to sustainability standards. The analysis reveals variations within the same extraction method, influenced by solvent choice and operating conditions, as well as differences across the techniques, highlighting the importance of process design in achieving green and efficient valorization. Full article

The olive tree (Olea europaea L.) has been cultivated for millennia, with olive oil representing both a cornerstone of the Mediterranean diet and a major agricultural commodity. Its composition, rich in monounsaturated fatty acids, polyphenols, tocopherols and squalene, supports well-documented cardioprotective, antioxidant and anti-inflammatory benefits. Olive oil production generates substantial secondary streams, including pomace, leaves, pits and mill wastewater, which are rich in phenols, triterpenes and fibers. This review consolidates recent advances in their phytochemical characterization, innovative extraction technologies and health-promoting effects, while highlighting the economic and regulatory prospects for industrial adoption. Comparative analysis shows that olive leaves can produce up to 16,674.0–50,594.3 mg/kg total phenolics; oleuropein 4570.0–27,547.7 mg/kg, pomace retains 2.24 g GAE/100 g dried matrix (DM)total phenolics; oil 13.66% DM; protein 6.64% DM, and wastewater contains high concentration of phenolics content of olives. Innovative extraction techniques, such as ultrasound and microwave-assisted methods, allow for a recovery, while reducing solvent use and energy input. The analysis highlights opportunities for integrating these by-products into circular bioeconomy models, supporting the development of functional foods, nutraceutical applications and sustainable waste management. Future research should address techno-economic feasibility, regulatory harmonization and large-scale clinical validation to accelerate market translation. Full article

Microwave Breast Imaging (MWBI) is an emerging imaging modality aiming to detect breast lesions, which are dielectrically contrasted against the background healthy tissue, in the microwave frequency spectrum. MWBI holds potential to outperform X-ray mammography’s low sensitivity in young and dense breasts, thus supporting timelier detection of interval cancers, as a supplemental screening or diagnostic imaging method. The specificity of MWBI remains unknown, however, as management of false positives has not been systematically addressed yet. An earlier First-In-Human clinical investigation on 24 symptomatic patients provided proof-of-concept for the Wavelia MWBI sectorized multi-static radar imaging technology, which generates clinically meaningful 3D images of the breast, performs semi-automated detection of breast lesions and extracts diagnostic features to distinguish malignant from benign lesions. This paper focuses on a set of technological upgrades, accessories and data processing modules, designed and implemented in the 2nd generation prototype of Wavelia, to handle the diversity in breast geometry, tissue consistency and deformability, in a larger clinical investigation reporting on the bilateral MWBI scan of 62 patients. The presented add-on modules contribute to enhanced quality of scan and a more valid reference reporting space for the MWBI imaging outputs, with a direct positive impact on overall specificity. Full article

Phycocyanin, a blue pigment from Arthrospira platensis, is widely used as a natural colorant in food products, but its application is limited by its sensitivity to light and temperature during extraction and storage. This study explored the impact of UV light on phycocyanin extracted from A. platensis using a microwave-assisted method. Water proved to be the most effective solvent, yielding the highest phycocyanin concentration and stability. The optimal extraction conditions to avoid phycocyanin degradation were identified as 45 °C and 100 W of microwave power. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analysis revealed increased chemical complexity at higher temperatures and identified biopterin–pentoside complexes, which enhanced phycocyanin stability during UV degradation. These findings provide new insights into the molecular mechanisms of interactions between phycocyanin and proteins, enhancing phycocyanin stability and functionality and thus providing food products with longer shelf lives by maintaining their nutritional and aesthetic qualities. Full article

This study investigated the physicochemical properties of Camellia oleifera husks collected from three regions of Jiangxi Province (Ganzhou—GZ, Yichun—YC, and Jiujiang—JJ) and extracted tea saponins via microwave-assisted solvent extraction (MASE), aiming to provide a theoretical basis for the high-value utilization of this agricultural by-product. The husks from YC were rich in bioactive compounds such as tea saponins (16.29 ± 0.02%), with lower cellulose (21.05 ± 1.05%) and lignin (12.48 ± 1.14%) contents and higher hemicellulose (27.40 ± 0.80%) content. The husks from JJ exhibited abundant porosity and a larger specific surface area (40–60 mesh, 4.15 ± 0.04 m²/g). Single-factor extraction experiments indicated that the microstructure and chemical composition of Camellia oleifera husks significantly affected the extraction efficiency of saponins, tannins, and flavonoids. The optimal extraction conditions for tea saponins were established using Box–Behnken response surface methodology, with the liquid-to-solid ratio identified as the most critical factor. Optimal conditions for GZ husks were a liquid-to-solid ratio of 46.75 mL/g, ethanol concentration of 35.5%, extraction time of 6 min, and microwave power of 350 W, with the extraction yield of 7.49 ± 0.01%. Optimal conditions for YC husks were a liquid-to-solid ratio of 50.55 mL/g, ethanol concentration of 40.13%, extraction time of 6 min, and microwave power of 350 W, with the extraction yield of 16.29 ± 0.02%. Optimal conditions for JJ husks were a liquid-to-solid ratio of 47.44 mL/g, ethanol concentration of 37.28%, extraction time of 6 min, and microwave power of 350 W, with the extraction yield of 9.39 ± 0.02%. The study provides important scientific evidence for understanding the structure–function relationship of Camellia oleifera husks and offers practical guidance for developing sustainable industrial processes to convert agricultural by-products into high-value bioactive compounds, thereby promoting resource recycling and economic benefits in the Camellia oleifera industry. Full article

Optical-carried microwave interferometry (OCMI) has attracted increasing attention in recent years, as it combines the ease of phase extraction and manipulation of microwave techniques with the low-loss transfer of optical fibers. Conventional OCMI implementations typically employ broadband light sources and coherent photodetection, which inevitably suffer from dispersion, polarization fading, and phase drift, severely limiting the achievable sensing distance. In this work, we proposed an optimized OCMI architecture that adopts incoherent photodetection combined with electric-domain microwave interferometry. Comprehensive theoretical analysis and systematic experiments demonstrate that the proposed system enables robust, dynamic, and long-haul fiber transfer delay (FTD) measurements, no less than in 15 km length, with improved resolution and stability. It provides new insight for building long-haul FTD sensor networks. Full article

Medicinal and Aromatic Plant (MAP) by-products constitute a vast reservoir of bioactive metabolites with antioxidant and antimicrobial properties, offering potential for the development of high added value natural products. This study focuses on the by-product (tepals) remaining during the process of receiving the stigma of Crocus sativus L. Iridaceae (saffron), which is the commercially exploitable part of the flowers. The tepals are the main part of the flowers (>95%) and are still discarded in the fields during the collection of the stigmas in Kozani, Greece. According to numerous findings, the saffron tepals are rich in flavonoids with notable biological properties, and our aim was to investigate an alternative for their management. Within this context, dry and frozen tepals were extracted at a laboratory scale through microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE), followed by adsorption resin technology (ART) for the preparation of enriched extracts. Furthermore, their HPTLC profiling, the phenolic (TPC) and flavonoid (TFC) content, and the free-radical-scavenging (DPPH) and anti-tyrosinase activity were evaluated. The frozen tepals were further extracted at a pilot scale using MAE and maceration (Mc) techniques, followed by ART treatment to remove the contained sugars. The enriched extract produced at a pilot scale using MAE and ART sequentially is characterized by a high phenolic (147.2 mg GAE/g dry extract) and flavonoid (114.8 mg QUE/g dry extract) load. These findings demonstrate that saffron tepals, traditionally considered waste, can serve as a valuable raw material for producing extracts rich in phenolic derivatives, particularly flavonoids and anthocyanins. Full article

This review examines recent advances in the extraction of valuable compounds from seaweed biomass, focusing on practical feasibility and environmental sustainability. There is a growing importance of seaweed biomass in terms of the study and acknowledgment of its untapped biotechnological potential (multiple compounds and biological activities) and in terms of economic impact. Conventional extraction techniques largely fail to address this challenge, even if optimized. This has led to the development and testing of innovative technologies as solutions for a ‘green’ and effective extraction of components from seaweed biomass and to biorefinery processes. There are large differences in outcomes between alternative processes, depending on the matrix, operational parameters, and targeted compounds and activities. Despite the positive results of some techniques, such as those based on physical mechanisms, namely Microwave-Assisted Extraction (MAE) and Ultrasound-Assisted Extraction (UAE), and on enzymatic selectivity, i.e., Enzyme-Assisted Extraction (EAE), there is no universally effective technique and approach, thus justifying integrated approaches combining different techniques. The application of ‘green’ solvents was also assessed and proven to harbor a large potential, just as the wet route. Although technical difficulties, outcome variability, and economic viability problems are relevant, recent progress in seaweed processing paves the way for a future blue economy. Full article

Tomato processing residues—including peels, seeds, and pomace—are rich in bioactive compounds, such as lycopene, β-carotene, cutin, pectin, and antioxidants, yet are often underutilized. This study evaluates microwave-assisted extraction (MAE) and high-pressure-assisted extraction (HPAE) for the recovery of carotenoids from TP, compared to conventional extraction (CE) using ethyl acetate. Optimal MAE conditions (150 W, 50 °C, 20 min, solid/liquid ratio of 1:10 g/mL) yielded 592.5 mg carotenoids/kg dry weight (dw), exceeding CE yields (505.3 mg/kg dw), while significantly reducing extraction time (20 min vs. 120 min). By contrast, direct HPAE (650 MPa, ambient temperature, solid/liquid ratio of 1:10 g/mL) resulted in lower carotenoid yields (ca. 84 mg/kg dw), but when used as a pre-treatment followed by stirring for 24 h, HPAE enhanced carotenoids extractability to 277.0 mg/kg dw, recovering 55% of carotenoids extracted by CE. Bioaccessibility studies showed low lycopene bioaccessibility across all methods (3.9% for HPAE, 3.4% for MAE, and 1.6% for CE). Incorporation into oils significantly improved bioaccessibility, with olive pomace oil (OPO) achieving 28.1%, compared to 8.1% in corn oil (CO). Overall, MAE and HPAE (as pre-treatment) present efficient strategies that reduce solvent usage and processing time, though they still rely on organic solvents, while strategies to enhance bioaccessibility should further be explored for effective functional ingredient development. Full article

This review concentrates on the bioactive potential of two significant agri-food by-products: coffee by-products (coffee pulp and husk, spent coffee grounds, and silverskin) and olive by-products (olive mill wastewater, pomace, stones, and leaves). These residues are produced in substantial quantities, and despite their considerable application potential, they remain predominantly underutilized, thereby contributing to environmental burdens and economic losses. Their richness in bioactive compounds is unequivocal. Specifically, coffee by-products are abundant in caffeine and chlorogenic acids, whereas olive by-products serve as excellent sources of oleuropein, hydroxytyrosol, and tyrosol. Such compounds possess health-promoting properties and are promising active ingredients for cosmetic formulations, owing to their antioxidant, anti-aging, UV protective, antimicrobial, emollient, and moisturizing effects. This review not only compiles the bioactive compounds present in these by-products and explores their potential applications but also examines the extraction methods employed for their recovery. Both conventional techniques (solvent extraction) and green extraction technologies (ultrasound-assisted extraction, microwave-assisted extraction, and supercritical fluid extraction) are discussed. These innovative and environmentally friendly approaches enhance extraction efficiency and are aligned with sustainability objectives. In this context, the importance of incorporating natural ingredients into cosmetic products is emphasized, both to meet regulatory and environmental standards and to satisfy the increasing consumer demand for safer, more effective, and environmentally sustainable formulations. Full article

Rosa damascena and Rosa rugosa, which are the two most commercial species in the Rosa genus, are used to make rose oil, cosmetics, and functional foods. The majority of polysaccharide constituents of both species is structurally diverse and demonstrates promising biological activities, such as moisturizing, immunomodulation, and antioxidant activity. The extraction technique has a significant impact on the yield, purity, and bioactivity of polysaccharides. Traditional extraction methods (hot water, ethanol) are simple and economical, yet they typically produce low yields and degrade sensitive compounds. Novel extraction methods (pressurized liquid extraction, enzyme-assisted extraction, ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction) offer higher efficiency, selectivity, and sustainability, while better preserving polysaccharide structure and bioactivity. This review serves as a comparative summary of conventional versus novel extraction methodologies of polysaccharides from R. damascena and R. rugosa, with particular consideration towards the yield, polysaccharide structural integrity, sustainability, and industrial conduct of each methodology. In addition, it summarizes the distribution and functional role of selected polysaccharides in the various organs of the plants, while also providing an overview of their antioxidant mechanisms and potential bioactive applications in health. Challenges and critical factors that surround specific species, standards for processes, and extraction methods, and that therefore appeal to time and economic considerations, are identified. In efforts to optimize the extraction methodology, the high economic and functional potential of the Rosa species can be maximized in the interest of healthy, functional consumables for the pharmaceutical, nutraceutical, and cosmetic industries. Full article

Carbon microspheres were prepared by microwave-assisted hydrothermal treatment, at 180 °C, of commercial carbohydrates (saccharose, glucose, and xylose) and xylose extract obtained from almond shells with varying synthesis parameters. When 1.6 M aqueous solutions of commercial carbohydrates were used, 2–10 μm carbon microspheres were obtained from saccharose after 15 min, while a longer amount of time (60 min) and the addition of acid medium (1% v/v H₂SO₄, 1% v/v H₃PO₄) were needed to obtain carbon microspheres from commercial xylose and glucose (≤ 1 μm). The higher reactivity of saccharose could be related to the formation, during heating, of fructose, which is more reactive than glucose and xylose. An increase in the acid concentration and in the carbohydrate concentration increased the formation and size of the microspheres. Comparative experiments with conventional heating did not produce a solid. Interestingly, when xylose extract obtained from almond shells was used, small carbon microspheres (1–3 μm) were obtained at a much lower concentration (0.2 M) and time (15 min) than with commercial xylose. This could be related to the acid medium used during extraction of xylose from the biomass. Activation of microspheres with CO₂ resulted in high-surface area materials (243–326 m²/g) with great potential as catalytic supports. Full article

Natural deep eutectic solvents (NADESs) are emerging green solvents widely applied to improve the extraction of essential oil (EO) through plant tissue pretreatment. Various NADESs, formulated from polyalcohols, sugars, and organic acids, were employed as pretreatment solvents prior to microwave-assisted hydrodistillation (MAHD) to facilitate plant cell wall breakdown and improve the efficiency of EO extraction. The findings revealed that the most effective pretreatment conditions for enhancing EO extraction involved using a NADES composed of choline chloride and glycerol (in a 1:2 molar ratio), applied to fennel seed powder at a solid-to-NADES ratio of 1:6 g/mL. Optimal performance was achieved with 20% water content in the NADES, microwave irradiation at 400 W for 6 min, followed by 96 min of MAHD. Under these conditions, the NADESs-based MAHD achieved the highest EO yield, increasing it from 1.33% with water-based MAHD to 2.70%. Fennel EO demonstrated the strongest antimicrobial activity against S. pyogenes and C. albicans., while the EO obtained from NADES-MAHD using Ch:Gly (1:2) showed the highest antioxidant activity, with 72.41% inhibition. Finally, GC-MS phytochemical analysis of the extracted EOs revealed anethole as the major compound. Notably, the application of NADES, particularly Ch:Gly (1:2), enhanced the relative content of monoterpene hydrocarbons. These findings highlight the superior effectiveness of deep eutectic solvents during the pretreatment stage in enhancing EO production. Full article

This study aimed to optimize the extraction of total phenolic compounds (TPC) from Tunisian walnut bark using microwave treatment. Initially, a preliminary investigation was conducted to establish optimal levels for ethanol concentration, liquid–solid ratio, temperature, and time, which were then applied in subsequent conventional solvent extraction (CSE) experiments. To enhance the extraction yield, multi-stage microwave-assisted extraction (MS MAE) was evaluated using three microwave power settings: 100, 200, and 300 W. The results showed a statistically significant (p < 0.05) effect of microwave irradiation combined with multiple solvent extraction stages. The optimized MS MAE protocol, employing 300 W power, six stages of 10 min each, and a liquid–solid ratio of 10 mL/g, achieved an 86% recovery of TPC. In contrast, extraction involving 10 stages of 30 min each without microwave irradiation recovered only 79% of TPC. UHPLC–MS analysis revealed that the phenolic profile of the extracts was dominated by gallic acid, vanillic acid, and quercetin, and that microwave treatment did not significantly alter the qualitative or quantitative composition of these major phenolic compounds compared to conventional extraction. These findings demonstrate that MS MAE is a time-saving, energy-saving, solvent-reducing, and highly efficient extraction technology for producing bioactive extracts from walnut bark. Full article

Reliable sea ice extent (SIE) information is essential for Arctic navigation, climate research, and resource exploration. Synthetic Aperture Radar (SAR), with its all-weather, high-resolution capabilities, is well suited for SIE extraction. This study evaluates a pan-Arctic SIE product automatically generated from over 85,000 Sentinel-1 SAR images acquired between 2020 and 2023 using an integrated stacking U-Net framework. To validate its performance, all the SIE products are converted to sea ice concentration (SIC) and compared against the 3.125 km resolution Advanced Microwave Scanning Radiometer-2 (AMSR2) SIC products. The S1-derived SIC shows strong agreement with AMSR2 SIC, yielding a Pearson correlation of 0.99 and annual mean absolute differences between 5.93% and 7.85%. Case analyses demonstrate that the S1 products effectively capture small-scale ice features, such as floes, which are often missed by AMSR2. Furthermore, we introduce an Integrated Index to quantify the relative contribution of each sub-model within the integrated stacking U-Net framework. The analysis indicates that three sub-models provide the primary contribution to the ensemble, offering insights into improving integration efficiency and guiding the design of more scientifically grounded ensemble strategies. Full article