Search Results (201)

Pleurotus ostreatus, commonly known as the oyster mushroom, is a widely cultivated edible mushroom characterized by its nutritional value and health benefits. However, its large-scale production generates significant amounts of agro-industrial by-products, such as stipes, residual mycelium, and spent mushroom substrate (SMS). These by-products are often discarded despite their high content of bioactive compounds such as dietary fiber, β-glucans, polyphenols, ergosterol, and essential minerals. This review provides a critical overview of emerging green extraction technologies (i.e., ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), subcritical water extraction (SWE), enzyme-assisted extraction (EAE), and pulsed electric fields (PEF)) as a strategy for the sustainable valorization of bioactive compounds from P. ostreatus by-products. Despite promising results in the extraction of β-glucans and phenolic compounds, industrial scalability remains a challenge due to cost, energy demand, and regulatory issues. In addition, the potential incorporation of these compound by-products into functional food formulations is explored, highlighting their possible applications in meat, bakery, and dairy products. Although notable outcomes have been obtained in the use of the fruiting body as a functional ingredient, further research is needed into the potential use of by-products in order to optimize processing parameters, ensure safety, and validate consumer acceptance. Overall, the sustainable valorization of P. ostreatus by-products represents a dual opportunity to reduce food waste and develop innovative functional ingredients that contribute to health and sustainability. Full article

This study explores the development of functional fermented beverages using fibre-rich residues derived from olive pruning, vineyard pruning, chicory root, and red onion, obtained after subcritical water extraction of polyphenols. Two microbial strains, Lactiplantibacillus plantarum and Bacillus subtilis, were evaluated for their fermentation performance across different fibre matrices, with and without sugar supplementation. Key parameters including microbial growth, pH evolution, and reducing sugar content were monitored, and Lactiplantibacillus plantarum showed superior acidification and viability (>9 log CFU/mL), especially in sugar-enriched formulations, while Bacillus subtilis showed a limited performance. Based on fermentation efficiency, three sugar-supplemented formulations were selected to scale-up: olive pruning fibre and vineyard pruning fibre fermented with Lactiplantibacillus plantarum and olive pruning fibre fermented with Bacillus subtilis. Red onion fibre extract was excluded from scale-up experiments due to its high viscosity, which made it impossible to measure reducing sugars, consistent with its high water-holding capacity. Fermentation significantly increased antioxidant capacity, reaching up to 750 µmol Trolox equivalents/L and 18 mg of gallic acid equivalents/L in L. plantarum-fermented samples, confirming microbial release of bound phenolics and formation of bioactive metabolites. The resulting beverages were microbiologically stable (final pH < 4.5), sensorially acceptable, and potentially antioxidant-rich, supporting their role in sustainable food system development and circular bioeconomy. Full article

Regulatory changes in the EU for safety purposes require strict control and high safety standards for essential oils obtained by steam distillation, as they are classified as chemical mixtures with potential toxic effects. Subcritical water extracts (SWEs) are considered safer. This study evaluated the cytotoxicity and genotoxicity of SWEs from Rosa damascena Mill. and Rosa alba L. in three test systems at different hierarchical levels: higher plants (root meristems of Hordeum vulgare), somatic cells of Mus musculus ICR strain, and human lymphocytes in vitro. The chromatographic fingerprint of the extracts revealed the presence of key components such as flavonoids, phenolic acids, and glycoside derivatives, with species-dependent variations and concentrations. No significant cytotoxicity was detected in the concentration range of 6–20%. SWE from R. alba showed a higher level of safety at high doses. Genotoxicity tests showed a weak, dose-dependent induction of chromosomal aberrations and micronuclei in barley and lymphocytes (greater in R. alba), a lack of genotoxicity in mouse bone marrow, and a slight increase in micronuclei in mouse erythrocytes after exposure to R. alba extract. The results highlight the suitability of SWEs from R. damascena and R. alba for safe application in the medical, food, and cosmetic industries. Full article

In line with the circular economy approach and the pursuit of sustainable solutions for spent coffee grounds, this study investigates the valorization of spent coffee grounds as a source of cellulose-based enzyme immobilization carriers. Considering that global coffee consumption generates approximately 6.9 million tonnes of spent coffee grounds annually, their disposal represents both an environmental challenge and an opportunity for value-added applications. A multistep extraction process, including Soxhlet extraction followed by sequential subcritical extraction with ethanol and water, and alkaline treatment, led to the production of cellulose-enriched carriers. The carriers obtained were characterized by their morphology, porosity and surface properties and subsequently used for the two lipases immobilization, Burkholderia cepacia (BCL) and Pseudomonas fluorescens (PFL), using three techniques: adsorption and covalent binding via direct and indirect methods. The immobilized lipases were analyzed for key biochemical and operational properties and compared with each other and with their free enzymes. Based on their stability, catalytic activity, and reusability, the lipases immobilized by adsorption were identified as the most efficient biocatalysts. These immobilized enzymes were then used in two selected reactions to demonstrate their practical utility: cocoa butter substitute synthesis using PFL and the enzymatic pretreatment of wastewater from the oil processing industry using BCL. Both immobilized lipases showed excellent catalytic performance and maintained their high activity over four consecutive reuse cycles. Full article

The white oil-bearing Rosa alba L. was subjected to green subcritical water extraction. The two factor modeling process revealed that 150 °C and 30 min treatment resulted in the maximum yield of phytochemicals, including essential oils, phenolic compounds, total carbohydrates, proteins, and simple sugars. A quantitative and qualitative analysis of the products was performed. The essential oil contained mainly phenylethyl alcohol, citronellol, geraniol, and hydrocarbons (paraffins). The phenolic substances were represented by phenolic acids (gallic acid: 30.92–113.37 µg/mL; ferulic acid: 44.50–99.96 µg/mL; rosmarinic acid: 25.27–80.47 µg/mL; protocatechuic acid: 13.05–25.48 µg/mL), as well as flavonoids (both quercetin and kaempferol: 8.35–8.56 µg/mL) and their glycosides (15.91–58.08 µg/mL). The monosaccharides were determined to include glucose (3.09–15.29 mg/mL), galacturonic acid (1.02–2.34 mg/mL), galactose (0.18–0.78 mg/mL), rhamnose (0.17–0.48 mg/mL), and xylose (0.07–0.17 mg/mL). The content of total phenols, flavonoids, and antioxidant activity were reported by the DPPH, ABTS, FRAP, and CUPRAC methods. The complex composition and activity of the extracts suggests their application directly as a food supplement or in cosmetic preparations. Full article

Global wine production reached about 226 million hectolitres in 2024, with Europe as the largest producer. The winemaking industry generates substantial amounts of by-products, presenting both economic and environmental challenges, as approximately 30% of processed grapes are discarded as waste. This study evaluates various polyphenol extraction techniques from wine residues, utilising data from the literature. Techniques assessed include subcritical water extraction, ultrasound-assisted extraction, conventional solvent extraction, and microwave-assisted extraction, each preceded by a suitable pretreatment. Results show that the extraction method, temperature, solvent, and feedstock type have a strong influence on environmental impacts. Microwave extraction from exhausted grape marc had the highest impact due to its low yields and high energy use during freeze drying. In contrast, subcritical water extraction from red wine residues was the most sustainable, benefiting from its high efficiency, use of water as a solvent, and the rich polyphenol content of red grape residues. When included, drying was the primary contributor to greenhouse gas emissions. Climate change and energy demand were key impact categories, with a renewable energy scenario potentially reducing impacts by up to 90%. Results demonstrate that no single extraction method is universally best; choices must balance efficiency and energy use. This work supports optimising sustainable polyphenol recovery within circular economy and climate goals. Full article

The present study focuses on recovering phenolic compounds and terpenes from olive leaves, which are generated as by-products during olive oil processing. To this end, conventional extraction/maceration (CE) and advanced extraction techniques such as subcritical water extraction (SWE), pressurized fluid extraction (PLE) and ultrasound-assisted extraction (UAE) were employed to compare and determine the most effective procedure. The phenolic and terpenoid composition of the extracts revealed a total of 33 compounds in HPLC-QTOF-MS analysis. According to these findings, the optimal extraction techniques for the maximum recovery of secoiridoids from olive leaves were PLE and UAE, with no significant difference between them (21.9891 ± 2.5521 mg/g DW and 21.0888 ± 1.3494 mg/g DW, respectively). Regarding to flavonoids, UAE was the most effective extraction technique, yielding 4.9837 ± 0.6739 mg/g DW. However, SWE recovered the highest amount of phenolic alcohols (7.4201 ± 0.9848 mg/g DW), which could be due to degradation of the secoiridoids during extraction. Conversely, UAE was more successful than the other techniques for the extraction of the terpene family (0.7373 ± 0.0601 mg/g DW). The present study therefore focuses on comparing different extraction techniques for revalorizing olive leaves as a source of bioactive compounds, specifically polyphenols and terpenes, due to their beneficial health properties. Full article

Development of biodegradable packaging materials and valorization of agri-food waste are necessary to produce more sustainable materials while reducing the environmental impact. Starch-based biocomposite films reinforced with beer bagasse fractions with different purification degrees were developed and characterized in structural, mechanical, thermal and optical properties. To this aim, 5% and 10% (w/w) of either beer bagasse (BB) or its lignocellulosic-rich fibers (LF), obtained by subcritical water extraction at temperatures between 110 and 170 °C, were incorporated into starch matrices. Elastic modulus and tensile strength values increased by up to eight-fold and 2.5-fold, respectively, compared to the control film. The incorporation of BB or LF significantly enhanced the mechanical resistance of the films. In general, the increment in the filler:polymer ratio significantly increased the EM values (p < 0.05), while decreasing the stretchability of the films around 80–85%, regardless of the type of filler. This effect suggests a good interfacial adhesion between the fillers and the polymeric matrix, as observed by FESEM. The biocomposite films exhibited a dark reddish appearance, reduced transparency, light blocking barrier capacity and remarkable antioxidant activity due to the presence of phenolic compounds in the fibers. The water vapor and oxygen barrier properties were better preserved when using the more purified LF obtained at 170 °C. Overall, starch films reinforced with beer bagasse fractions showed strong potential for the development of biodegradable food packaging materials. Full article

Light-emitting diodes (LEDs) are made up of precious metals, e.g., gallium. These elements can be recovered and reused, reducing the need for new raw materials. Proper recycling prevents harmful substances in LEDs, such as lead and arsenic, from contaminating the environment. Recycling LEDs uses less energy compared to producing new ones, leading to lower carbon emissions. The valuable metal gallium faces the challenge of supply and demand due to the surge in its demand, the difficulty of separating it from minerals, and processing issues during extraction. In this review, we describe the methods for recycling gallium from LEDs by using different techniques such as pyrolysis (95% recovery), oxalic acid leaching (83.2% recovery), HCL acid leaching of coal fly ash (90–95% recovery), subcritical water treatment (80.5% recovery), supercritical ethanol (93.10% recovery), oxidation and subsequent leaching (91.4% recovery), and vacuum metallurgy separation (90% recovery). Based on our analysis, hydrometallurgy is the best approach for recovering gallium. It is reported that approximately 5% of the waste from LEDs is adequately recycled, whereas the total gallium potential wasted throughout production is over 93%. By recycling LEDs, we can minimize waste, conserve resources, and promote sustainable practices. Thus, recycling LEDs is essential for strengthening a circular economy. Full article

Pectin is a multifunctional polysaccharide whose structural attributes, including degree of esterification (DE), molecular weight (MW), and branching, directly affect its gelling, emulsifying, and bioactive properties. Conventional pectin extraction relies on acid- or alkali-based methods that degrade the pectin structure, generate chemical waste, and alter its physicochemical and functional properties. Although novel methods such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and enzyme-assisted extraction (EAE) are recognized as environmentally friendly alternatives, they frequently use acids or alkalis as solvents. This review focuses on pectin extraction methods that do not involve acidic or alkaline solvents such as chelating agents, super/subcritical water, and deep eutectic solvents (DESs) composed of neutral components. This review also discusses how these alternative extraction methods can preserve or modify the key structural features of pectin, thereby influencing its monosaccharide composition, molecular conformation, and interactions with other biopolymers. Furthermore, the influence of these structural variations on the rheological properties, gelling behaviors, and potential applications of pectin in the food, pharmaceutical, and biomedical fields are discussed. This review provides insights into alternative strategies for obtaining structurally intact and functionally diverse pectin by examining the relationship between the extraction conditions and pectin functionality. Full article

The aim of this work was to extract phenolic compounds (PCs) from Cistus ladanifer L. post-distillation residues using two different methods (solid–liquid extraction (SLE) and subcritical water extraction (SWE)) and to compare the extracts’ total phenolic content (TPC) and antioxidant activity (AA) by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH^•) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^•+) scavenging activities, as well as by the ferric-reducing antioxidant power (FRAP) assay. SWE extraction displayed a higher TPC value (increased from 146.53 ± 11.68 to 276.37 ± 20.59 mg gallic acid equivalents (GAEs)/g extract dry weight (dw)) and higher AA in the DPPH^• (increased from 334.27 ± 36.06 to 532.17 ± 66.38 mg Trolox equivalents (TEs)/g extract dw), ABTS^•+ (increased from 438.07 ± 77.22 to 594.08 ± 33.57 mg TEs/g extract dw), and FRAP (increased from 10.91 ± 2.03 to 170.26 ± 25.36 mg ascorbic acid equivalents (AAEs)/g extract dw) assays. These results demonstrate the importance of the extraction method in PC extraction and the antioxidant power of the extracts produced. These results provide critical insights into the potential application of C. ladanifer post-distillation residues and the production of polyphenol rich extracts that might be useful in the food, cosmetic, and pharmaceutical sectors. Full article

Oilseed cakes, by-products of oil extraction, represent an underutilized resource with significant potential for sustainable food and pharmaceutical applications. This comprehensive review examines the valorization strategies for oilseed cakes, focusing on their rich protein (up to 56%) and fiber (up to 66%) content. We analyze both conventional and innovative extraction methods, highlighting the advantages of ultrasound-assisted (96.64% phenolic compound yield), enzymatic (82–83% protein recovery), and subcritical water extraction techniques in improving efficiency while reducing environmental impact. This review demonstrates diverse applications of oilseed cake components from gluten-free bakery products and plant-based meat alternatives to advanced nanoencapsulation systems for bioactive compounds. Each major oilseed type (soybean, rapeseed, sunflower and flaxseed) exhibits unique nutritional and functional properties that can be optimized through appropriate processing. Despite technological advances, challenges remain in scaling extraction methods and balancing yield with functionality. This paper identifies key research directions, including the development of integrated biorefinery approaches and the further exploration of health-promoting peptides and fibers. By addressing these challenges, oilseed cakes can play a crucial role in sustainable food systems and the circular economy, transforming agricultural by-products into high-value ingredients while reducing waste. Full article

Biorefinery is gaining attention as a promising approach to valorize natural resources and promote a circular bioeconomy. This study aimed to recover high-value molecules, such as xanthophylls and polar lipids with nutraceutical applications, through enzymatic pretreatment and sequential pressurized liquid extraction (PLEseq), by reusing the residual biomass of Nannochloropsis gaditana after each processing step. Remarkably, pure glycolipids (102.95 ± 1.10 mg g⁻¹ dry weight) were obtained immediately after enzymatic pretreatment, facilitating their easy recovery. Furthermore, two alternative sequential extraction processes were successfully developed, using ethanol and water as green solvents at varying temperatures and in different orders. The most effective PLEseq conditions yielded up to 48 mg mL⁻¹ of carbohydrates using water at 50 °C, and up to 44 mg mL⁻¹ of proteins via subcritical water extraction at 100 °C, prior to conventional lipid extraction with ethanol to produce various concentrated extracts. In the inverted PLEseq process—starting with ethanol extraction followed by successive water washes—isolated and purified fractions of lutein and astaxanthin were obtained, contributing to the complete depletion of the residual biomass. Overall, the development of an integrated and sequential biorefinery protocol that enables the extraction of multiple high-value compounds holds significant potential for application in the food industry. Full article

Subcritical water extraction (SWE) is an eco-friendly technology offering advantages such as green solvent and selectivity, especially for extracting bioactive compounds. Despite its potential, limited data exists on upscaling this process. This study investigates the upscaling of SWE by comparing two systems: a commercially available high-pressure system (ASE 200, 32 mL capacity) and high-volume subcritical water extraction (HVSWE) (1000 mL capacity). Medicinal compounds, 6-gingerol and 6-shogaol, were extracted from ginger using SWE at temperatures ranging from 130 °C to 200 °C, at a constant pressure of 3.5 MPa, for 30 min. High-Performance Liquid Chromatography (HPLC) was employed for quantitative analysis. The optimal extraction temperature for 6-gingerol using the high-volume SWE system was 130 °C, yielding 1741.54 ± 0.96 µg/g, whereas ASE 200 achieved optimal extraction at 140 °C with 1957.22 ± 2.55 µg/g. For 6-shogaol, both systems demonstrated an optimal extraction temperature of 170 °C, with yields of 541.78 ± 3.16 µg/g and 1135.23 ± 1.18 µg/g for the high-volume SWE and ASE 200 systems, respectively. These variations stem from the 35-fold difference in capacity, influencing heat and mass transfer during extraction. Thus, scale-up factors must be carefully considered to enhance the mass transfer efficiency and optimize SWE processes at larger scales. Full article

Grape seeds are a major by-product of the winemaking industry and a great source of bioactive compounds such as polyphenols and proteins. These compounds have a wide range of applications including those in nutraceutical products and cosmetics and within the wine industry itself. Subcritical water extraction (SWE) was explored as a global method to valorize grape seed by-products for their different bioactive compounds in the context of waste valorization, green chemistry (solvent-free extraction), and circular economy. A Box–Behnken design was applied to generate mathematical responses and the ANOVA analysis determined the optimal extraction conditions (pressure, temperature, and time of extraction) for different responses such as total polyphenol content (TPC), antioxidant activity (AA), and total protein (Tprot). Extraction temperature was found to be the most significant factor influencing all responses while pressure had no significant impact on them. Optimal conditions were derived from the mathematical models for each response. For polyphenol extraction, the optimal conditions were as follows: 170 °C and 20 bar for 39 min with 288 mg GAE/g DM. To achieve the highest AA, SWE parameters should be set at 165 °C and 20 bar for 51 min with 332 mg TROLOX/g DM. For the extraction of proteins, it is necessary to work at 105 °C and 20 bar for 10 min (78 mg BSA/g DM) to preserve protein functionality. In comparison, conventional solvent extraction was unable to outperform SWE with values under the SWE results. Given the high content of polyphenols found in the extracts, an HPLC analysis was conducted. The following compounds were detected and quantified: protocatechuic acid (7.75 mg/g extract), gallic acid (6.63 mg/g extract), delphinidin chloride (1.44 mg/g extract), catechin (0.36 mg/g extract), gentisic acid (0.197 mg/g extract), and some epicatechin (0.07 mg/g extract). Additionally, Maillard reaction products (MRPs) were detected at high temperatures, with 5-hydroxymethylfurfural (5-HMF) appearing in extracts processed at 165 °C and above. The presence of MRPs, known for their antioxidant and bioactive properties, may have contributed to the increased AA observed in these extracts. These findings are significant because a solvent-free extraction process like SWE offers a sustainable approach to repurposing winemaking by-products, with potential applications in the wine and food industries. Full article