Search Results (139)

Olive oil production is an economically and culturally important agro-industrial activity, particularly in Mediterranean regions, but conventional extraction processes generate significant quantities of by-products and may lead to the loss of valuable bioactive compounds. In this context, improving extraction efficiency while preserving oil quality and promoting sustainable processing has become a major research focus. This review examines the composition of virgin olive oil with particular attention to minor bioactive compounds and discusses how conventional processing technologies influence their distribution and retention. The environmental implications of traditional extraction systems, especially the generation of olive mill wastewater and solid residues, are also addressed. Furthermore, emerging and alternative extraction technologies are analyzed, including screw press (expeller) and supercritical CO₂ extraction, highlighting their potential to enhance the recovery of bioactive compounds and reduce environmental impacts. Particular emphasis is placed on water-free or reduced-water extraction approaches and on the valorization of olive mill by-products as part of a circular economy strategy. Overall, innovative extraction technologies can reconcile efficiency, sustainability and quality by minimizing polyphenol losses and wastewater generation, requiring further industrial optimization. Full article

The olive oil industry generates large amounts of by-products, particularly olive pomace and olive mill wastewater, which represent valuable sources of polyphenolic compounds with well-recognized antioxidant, anti-inflammatory, antimicrobial, and health-promoting properties. Within the framework of the circular economy, the valorization of these olive-derived residues has emerged as a promising strategy for converting low-value waste into high-added-value ingredients for food, pharmaceutical, and cosmetic applications. This review provides a comprehensive overview of recent advances in sustainable extraction and sample preparation approaches for the recovery of olive polyphenols, including ultrasound-, microwave-, enzyme-, and membrane-assisted technologies, as well as the use of green solvents and environmentally friendly extraction systems. Furthermore, the review discusses advanced analytical strategies for the identification and quantification of olive-derived polyphenols, covering chromatographic, spectrometric, electrophoretic, and miniaturized analytical platforms. Special attention is given to biopolymer-based encapsulation systems developed to enhance stability, controlled release, bioaccessibility, and bioavailability of these bioactive compounds. Finally, current challenges and future perspectives regarding the integration of green extraction technologies, analytical methodologies, and advanced delivery systems are highlighted to promote the sustainable exploitation of olive by-products within a circular economy framework. Full article

Olive mill wastewater (OMW), due to its high organic load and phenolic content, represents both a major environmental challenge and a promising low-cost substrate for microbial bioprocesses. In this study, lipid production by Yarrowia lipolytica using OMW was optimized through a mixed-level Taguchi experimental design. The effects of OMW dilution (%), nitrogen supplementation, NaCl concentration, sterilization, and carbon source (glucose or glycerol) were evaluated in terms of biomass production, lipid accumulation, and fatty acid composition. The results demonstrated a clear inverse relationship between biomass formation and lipid accumulation. The highest lipid content (33.49%) was achieved under nitrogen-limited conditions combined with a high OMW dilution. After 168 h of fermentation, the calculated lipid yield was 0.51 g/L. Biomass and lipid productivities were calculated as 0.22 g/L/day and 0.073 g/L/day, respectively. ANOVA analysis revealed that nitrogen concentration was the dominant factor affecting lipid production (67.71%), followed by NaCl concentration (18.83%). In contrast, OMW dilution, sterilization, and carbon source type were not statistically significant (p > 0.05), indicating that lipid production can be effectively performed under non-sterile conditions with flexible substrate utilization. Fatty acid analysis revealed that the produced lipids were rich in oleic acid (C18:1n9c), reaching up to 57.97%, with unsaturated fatty acids generally accounting for the majority of the total fatty acid composition. Although the carbon source had a limited effect on lipid yield, it contributed to variations in fatty acid composition, suggesting the possibility of tailoring lipid quality through substrate selection. Full article

Olive mill wastewaters (OWWs) are a phenol-rich by-product of olive oil production, associated with high disposal costs and significant environmental impact. This study evaluated the effects of OWW supplementation on Tenebrio molitor larvae (TML) reared on standard cereal-based substrates. Larval survival was not affected, but average body weight was significantly reduced in all OWW-treated groups, indicating a measurable impact on growth. Metabolomic profiling revealed alterations in amino acid, carbohydrate, and organic acid contents, including reductions in branched-chain and aromatic amino acids, trehalose, and Krebs cycle intermediates, particularly in groups with the strongest growth reduction. Lipid analysis showed stable saturated fatty acids, a shift from polyunsaturated to monounsaturated fatty acids, and an increase in total fat in the most affected groups. Despite the lack of enhancement in polyphenol accumulation or antioxidant activity, multivariate analysis highlighted distinct metabolic signatures between OWW-treated and control larvae, with sucrose, lactate, and fumarate identified as key discriminant metabolites. These findings demonstrate that OWW, a valorized olive oil by-product, can modulate growth and metabolism in TML, opening new perspectives for its application in innovative weight management strategies. Full article

The olive oil extraction industry produces large amounts of olive pomace and wastewater, both of which contain high levels of pollutants. In Albania, olive oil production has increased, while by-product challenges persist. Uncontrolled wastewater discharge and pomace burning have caused environmental issues and inefficient resource use. This study combines published data with field information to examine country pomace utilization and wastewater management. The regional distribution of extraction units and production volumes was analyzed to identify mismatches between processing capacity and output. The findings reveal discrepancies between official statistics and field data. Regional analysis highlights notable imbalances between the number of olive mills and their production volumes, especially in Elbasan, Fier, Vlora, and Berat. Projections, assuming three-phase technology, indicate increased generation of olive pomace and wastewater, thereby raising environmental risks associated with wastewater disposal. The potential for olive pomace oil production was estimated to reach up to 1600 tons. While progress has been made in establishing a pomace oil extraction plant, infrastructure gaps, weak regulation, and limited producer awareness need to be addressed to convert by-products into valuable resources and help Albania’s olive oil sector achieve sustainability goals. Full article

The present study investigates the potential of olive mill wastewater (OMW), supplemented with expired commercial glucose syrup, as a sustainable substrate for the submerged cultivation of Tuber spp. wild mushrooms. OMW contains considerable quantities of phenolic compounds, making it both a challenging pollutant and a promising nutrient source. To assess fungal performance under increasing phenolic stress, culture media were prepared with varying OMW concentrations (0–75% v/v on agar; 0–50% v/v in liquid media), while glucose was adjusted to ~30 g/L using expired glucose syrup. A sequential experimental approach was followed, beginning with Petri dish screenings on substrate/strain selection (measuring the mycelial growth rate; Kr, mm/day), progressing to 25-day shake flask fermentations and subsequently scaling up the most promising strain (Tuber mesentericum) in a controlled stirred-tank bioreactor. Throughout cultivation, substrate consumption (glucose, phenolics), pH evolution and decolorization were evaluated, while the resulting biomass was analyzed for polysaccharides, β-glucans, proteins, lipids, fatty acids, antioxidants, phenolic acids and triterpenoids content. Results showed that increasing OMW concentration enhanced tolerance and metabolic activity in selected Tuber species, with T. mesentericum exhibiting the highest resilience and achieving comparable or higher biomass yields in OMW-based media than in glucose (control). Phenolic removal exceeded 60% in flasks and 50% in the bioreactor, confirming simultaneous bioremediation capacity. Bioreactor cultivation demonstrated efficient substrate utilization and biomass production, while OMW-grown biomass presented high lipid content, enriched with unsaturated fatty acids, high β-glucan levels and increased antioxidant and phenolic profiles. Overall, this study demonstrates that OMW (supplemented with expired glucose syrup) can serve as a cost-effective and environmentally beneficial substrate for Tuber biomass production with dietary and antioxidant properties, offering an alternative source to mushroom carposomes, as well as supporting the circular bioeconomy strategies within olive oil processing industries. Full article

Industrial Symbiosis (IS) represents a key strategy within the Circular Economy (CE) paradigm, enabling firms located near enhance competitiveness through the collective exchange and valorisation of resources. By fostering the reuse of water, energy, and materials, IS contributes to the sustainable optimization of manufacturing processes. Nevertheless, the implementation of IS, as a distinct business model, requires the active collaboration of heterogeneous stakeholders, which often generates critical challenges in aligning interests and achieving equitable benefits. This study explores an innovative approach to agri-food symbiosis by evaluating the incorporation of Olive Oil Mill Wastewater (OOMW), a by-product of olive oil production, into bread formulations. This strategy not only mitigates the environmental burden associated with OOMW disposal but also promotes resource efficiency within the olive oil supply chain. Bread samples were produced by varying the concentration of OOMW, and each formulation was assessed according to quality characteristics, consumer acceptability parameters, and sustainability aspects. The selection of the best-performing formulation was conducted through a Multi-Criteria Decision-Making (MCDM) framework, specifically applying the VIKOR method. The findings highlight how the integration of OOMW into bread production can generate a dual benefit, improving food quality while advancing sustainable practices in both the olive oil and bakery sectors. Full article

Significant volumes of wastewater and solid by-products are produced by olive oil industries worldwide, posing serious environmental challenges. This study presents an innovative circular economy and environmental sustainability approach that simultaneously valorizes liquid (olive mill wastewater, OMW) and solid by-products (crushed olive pits) rom olive oil production through hydroponic lettuce cultivation. The OMW was pretreated and supplemented with nutrients (OMW-N) to create a hydroponic solution for lettuce (Lactuca sativa) cultivation using crushed olive pits as growing substrate. A hydroponic system fed with a nutritive solution was used as a control. Lettuces grown in the OMW-N system achieved a 100% survival rate with no signs of phytotoxicity, although they exhibited a significant reduction in fresh mass (approx. 66%) and size, compared to the control. The sensory analysis revealed no significant differences in consumer acceptance, except for slightly lower color intensity, with 40% of participants explicitly indicating a purchase preference for the OMW-N lettuce, validating its commercial feasibility. Results demonstrated that OMW-N system functioned as a tertiary treatment, achieving additional removal of nutrients. Overall, integrating treated OMW and olive pits into hydroponics is a feasible strategy to convert agro-industrial waste into value-added food products, reducing the environmental footprint of the olive sector. Full article

Background: Olive cultivation and olive oil production are key agricultural sectors in the Dalmatia region, where numerous oil mills operate. Analyses have shown that extra virgin olive oils (EVOO) produced in this area contain respectable amounts of polyphenols, which contribute to superior oil quality due to their antioxidant properties. During processing, hydrophilic phenolic compounds predominantly transfer into olive mill wastewater (OMW), making it a concentrated source of valuable bioactive molecules. The antioxidant, anti-inflammatory, and photoprotective effects of these polyphenols are highly relevant for cosmetic and pharmaceutical use. Methods: A total of 186 OMW samples were collected from oil mills in the Split-Dalmatia County across three production seasons (2023–2025). Total polyphenol content (TPC) was measured spectrophotometrically, while polyphenol composition was determined by High Performance Liquid Chromatography (HPLC). Antioxidant activity was evaluated using hydrogen atom transfer (HAT; 2,2-diphenyl-1-picrylhydrazyl) (DPPH), electron transfer (ET; ferric reducing antioxidant power) (FRAP), and oxygen radical absorbance capacity assay (ORAC). Results: The obtained results indicated high total polyphenols concentrations, with values ranging from 111.8 to 6717.2 mg of gallic acid equivalents per L of OMW (mg GAe L⁻¹). In the vast majority of analyzed samples, hydroxytyrosol was the predominant phenol compound. The antioxidant activity of the samples was high. Full article

With the advent of new analytical technologies and the urgent environmental problem, reopening investigations into polluting waste matrices becomes a priority. Olive mill wastewater is a pollutant and phytotoxic by-product of olive oil production. An untargeted UHPLC-QTOF analysis of three olive mill wastewaters from three different olive cultivars was performed, and modern informatic platforms were involved to characterize the chemical components in-depth. Data elaboration and statistical analysis confirmed the differences between samples and revealed a total of 364 annotated compounds, including iridoids, phenolic compounds, flavonoids, lignans, cinnamic acid derivatives, and pyrrolidine derivatives. Many of these metabolites, including compounds with known antioxidant and bioactive potential, are scarcely reported in olive products and by-products. The outcomes of this work could be useful for rethinking olive mill wastewater as a source of bioactive compounds to develop and optimize new detoxification strategies. Full article

Olive mill wastewater (OMW), a by-product of olive oil extraction, poses significant environmental challenges due to its toxicity and heterogeneity. This study evaluates the phenolic and mineral composition of OMW and alpechin sludges from abandoned ponds in Spain, and establishes a standardized conventional method to recover phenolic fractions and promote their safe valorization as bioactive ingredients. Phenolic compounds were identified by triple-TOF-LC-MS/MS, and minerals and heavy metals were quantified by ICP-MS. Across thirteen ponds analyzed, samples from Cordoba, Tarragona, Alicante and Toledo showed higher phenolic levels, ranging from 7.2 g GAE/kg to 18.9 g GAE/kg, with methanolic extracts reaching 10.98–15.67 mg GAE/mL. Thirty-one phenolic compounds were identified, predominantly luteolin, apigenin, quercetin, and secoiridoid derivatives, notably hydroxytyrosol and tyrosol, supporting their functional potential as natural antioxidants. The mineral profile was dominated by K and Ca and showed negligible carryover to the phenolic organic fraction (<1%). Heavy metal concentrations in fresh OMW were 0.32–1.06 µg/kg for Cd and Hg and 9–43.9 µg/kg for As and Pb. In OMW sludge, they ranged between 0.033 and 0.19 mg/kg for Cd, 0.01 and 0.12 mg/kg for Hg, 5.45 and 8.06 mg/kg for As, and 4.45 and 23.70 mg/kg for Pb, whereas phenolic extracts contained only 0.15–21.50 µg/kg, remaining below EU food safety limits. This work presents one of the first integrated approaches to risk-benefit mapping of abandoned ponds in Spanish soils and advances extraction standardization by jointly considering functional potential, contaminant profiles, and matrix location. Full article

Ethanol stress profoundly affects yeast metabolism, yet its integrated impact on lipase activity and lipid remodeling in Yarrowia lipolytica remains unexplored. Here, we investigated, for the first time, the combined effects of ethanol-induced stress on lipase production and fatty acid profiles in Y. lipolytica cultivated on two hydrophobic substrates: olive mill wastewater (OMW) and Waste Frying Oil (WFO). Ethanol was applied at increasing concentrations (3%, 5%, and 7% v/v), and the physiological responses were monitored over time (48, 72, and 96 h). Our results reveal a substrate-dependent and dose-dependent response to ethanol. Lipase activity was significantly enhanced at 5% ethanol, reaching 0.55 ± 0.11 U/mL in the OMW medium after 48 h. In comparison, mild stress (3%) induced the de novo synthesis of C20:1 (eicosenoic acid) and C20:2 (eicosadienoic acid), indicating reprogramming of lipid biosynthetic pathways. Oxidative stability, assessed by pressurized differential scanning calorimetry (PDSC), markedly improved in OMW-derived lipids, with τ_on increasing from 30.48 ± 0.80 to 47.07 ± 3.92 min and τ_max from 35.73 ± 0.62 to 54.04 ± 1.99 min under 3% ethanol. Conversely, WFO-derived samples exhibited lower oxidative stability and less pronounced changes in lipid composition. These findings demonstrate that Y. lipolytica adapts its lipid metabolism differently depending on the substrate, and that controlled ethanol exposure can enhance both lipase secretion and lipid oxidative resistance, underscoring its potential as a robust biocatalyst for sustainable biorefineries and the valorization of agro-food oil wastes. Full article

Olive mill wastewater is a polluting residue generated from the olive oil industry and is one which constitutes an environmental concern in Mediterranean countries. Composting has been reported as a viable valorization alternative, as it reduces the volume and the phytotoxic characteristics of OMW. In this study, several composts derived from OMW were evaluated under controlled conditions over two growing season pot experiments using Lactuca sativa as a test crop. The analysis focused on soil quality changes, crop yield, and plant development. Additionally, potential phytotoxicity was also evaluated through a direct acute toxicity plant growth test. Application of OMW composts improved soil fertility indicators, including oxidizable carbon, Kjeldahl total nitrogen, Olsen phosphorous, and plant availability. Crop yields were comparable to those obtained with other organic amendments such as vermicompost and fresh cattle manure in both growing seasons and plant development (in terms of chlorophyll content and canopy cover) was not negatively affected. Nutrient uptake (NPK) was consistent during both growing seasons, with similar nitrogen use efficiency to that achieved in other organic treatments. Regarding the potential toxic effect, the OMW composts tested enhanced seed germination when mixed with coconut fiber at weight ratios below 29.2%. No half-maximal effective concentration (EC50) values were detected, even at 100% compost concentration, while half-maximal inhibitory concentration (LC50) values ranged between 65–75%. These results indicate that OMW composts can serve as an effective short-term source of plant-available nitrogen and a medium-term source of phosphorus, without risk of finding inhibitory or phytotoxic effects on crops. Full article

The growing accumulation of non-biodegradable petrochemical plastics and increasing food waste present urgent environmental and public health challenges. This study addresses both issues by developing biodegradable food packaging films from agar and starch, enhanced with antimicrobial properties by incorporating silver nanoparticles. The innovation of this work is the synthesis of novel agar–starch–silver nanoparticle coatings, where the contained nanoparticles were produced via green methods using two agro-industrial by-products of Greek olive oil production—olive stone extract and olive mill wastewater—as reducing agents. The morphology of the novel coatings was confirmed using transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, revealing nanoscale particles with variable sizes. Additional film characterization was performed through Fourier-transform infrared spectroscopy, scanning electron microscopy coupled with energy-dispersive spectroscopy, and surface profilometry. Infrared spectroscopy analysis suggested the presence of functional groups responsible for nanoparticle stabilization, while energy-dispersive X-ray spectroscopy revealed silver aggregation in both olive stone extract and olive mill wastewater-derived films. Profilometry showed that films with olive mill wastewater-based nanoparticles had a rougher surface than those synthesized from olive stone extract. Antibacterial efficacy was tested against Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) using a spot-on-film assay with high (10⁶ CFU/film) and low (10³ CFU/film) bacterial loads. After 72 h of incubation at 4 °C, both film types showed strong antibacterial activity at high bacterial concentrations, demonstrating their potential for active food packaging. These findings highlight a promising approach to sustainable food packaging within the circular economy, utilizing agricultural waste to create biodegradable materials with effective antimicrobial functionality. 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