Search Results (830)

Citrus aurantium L. by-products are a valuable source of bioactive compounds with potential industrial applications. This study evaluated the use of natural deep eutectic solvents (NADESs), formulated with choline chloride as the hydrogen bond acceptor (HBA) and fructose as the hydrogen bond donor (HBD), combined with ultrasound-assisted extraction to optimize the recovery of flavonoids from Citrus aurantium L. industrial by-products. A central composite design (CCD) was employed to optimize total flavonoid content (TFC). The molar ratio (MR; 1 and 2 mol of HBD per mol of HBA) and the percentage of added water (AW; 40 and 60%) were optimized. In addition to TFC, total phenolic content (TPC), total ascorbic acid (TAA), antioxidant capacity (Ax) and phenolic profiles were also evaluated. The optimal extraction conditions, as obtained by Response Surface Methodology (RSM) for TFC, corresponded to an HBD molar ratio of 1.33 per 1 mol of HBA and 47.48% added water, resulting in an optimal value of 1576.63 ± 4.9 mg quercetin equivalents (QE)/100 g dry mass (DM). Maximum values of 4276.94 ± 25.4 mg gallic acid equivalents (GAE)/100 g DM for TPC, 2077.66 ± 21.3 mg/100 g DM for TAA and 88.09 ± 0.1% inhibition for Ax were also obtained. The optimal NADES was characterized by density, viscosity, pH, Fourier-transform infrared (FTIR) and Raman spectroscopy. Additionally, phenolic profiling revealed high concentrations of hesperidin (2747.1 mg/100 g DM), naringenin (1251.93 mg/100 g DM), and quercetin + luteolin (660.65 mg/100 g DM). Full article

‘Nagami’ kumquat (Fortunella margarita Swingle), a citrus fruit cultivated in Corfu, Greece, contains bioactive constituents whose levels may vary during fruit maturation. This study investigated changes in the physicochemical composition and bioactive potential of Corfu ‘Nagami’ kumquat during the commercial harvesting period (December–March) and optimized ultrasound-assisted extraction conditions for standardized comparisons among harvest stages. Fruits collected during the study period were analyzed for moisture, soluble sugars, proteins, lipids, total phenolic content, and free-radical scavenging capacity. Response surface methodology was used to optimize methanol concentration, extraction temperature, and extraction time, while principal component analysis (PCA) was applied to evaluate patterns associated with fruit maturation. During maturation, moisture and protein contents decreased, whereas lipid content increased. The optimized extraction conditions were 14% methanol, 45 min, and 54 °C. PCA showed clear separation of early- and late-harvest-stage samples, with the first two principal components explaining 97.9% of the total variability. The observed differentiation was primarily associated with DPPH scavenging, moisture, proteins, lipids, soluble sugars, and phenolic content. Late-harvest-stage fruits exhibited the highest free-radical scavenging capacity and phenolic content, with harvest stage related to variations in the bioactive potential of Corfu ‘Nagami’ kumquat. Full article

This study developed an oleic acid (OA)-functionalized, bio-derived calcium carbonate (Bio-CaCO₃) filler recovered from Asian green mussel (Perna viridis) shell waste for incorporation into a hydroxypropyl methylcellulose (HPMC)-glycerol (Gro) matrix as a hydrophobic composite coating for reducing pesticide deposition on mandarin surfaces. Aragonite-rich Bio-CaCO₃ was extracted through a combined chemical treatment and mechanical pulverization process. The extracted Bio-CaCO₃ was characterized by scanning electron microscopy, X-ray diffraction, laser diffraction, and ATR FT-IR spectroscopy. At the optimal OA concentration, surface functionalization yielded OA-functionalized Bio-CaCO₃ (OA-Bio-CaCO₃) powder beds that exhibited apparent superhydrophobicity; successful functionalization was confirmed by X-ray photoelectron spectroscopy. The resulting HPMC-Gro-OA-Bio-CaCO₃ coating dispersion (CD-OA) formed hydrophobic composite films (f-CD-OA), as demonstrated by water contact-angle measurements and surface-morphology analysis. The CD-OA coating formulation was successfully applied to mandarin surfaces by a dip-coating process. Colorimetric screening indicated that organophosphate pesticide residues on coated mandarins did not exceed hazardous levels, even at 20 times the manufacturer-recommended application rate. Quantitative LC-MS/MS and GC-MS/MS analyses demonstrated that the optimized CD-OA coating formulation provided substantial short-term protection against acetamiprid and chlorothalonil with pesticide-deposition reductions of 89% and ≥96%, respectively, after 1 d relative to pristine mandarins. These findings advance the functional reuse of biogenic CaCO₃ and offer a simple, water-based dip-coating approach that provides temporary surface protection for citrus production and food-safety management. Full article

Flavonoids are a diverse group of naturally occurring polyphenolic compounds found in plant-based foods and are known for their broad-spectrum biological activities. Among them, nobiletin, a polymethoxylated flavone derived from citrus peels, has gained attention for its multifaceted role in promoting healthy ageing and mitigating age-related diseases. This review explores the chemical properties, mechanisms of action, therapeutic potential, and challenges related to nobiletin. The focus is placed on its antioxidant, anti-inflammatory, neuroprotective, cardioprotective, and metabolic regulatory effects, as well as its capacity to enhance mitophagy, modulate circadian rhythms, and prevent ferroptosis. Despite promising preclinical results across various models, including in vitro cell lines, C. elegans, and mice, the clinical translation of nobiletin is hindered by poor oral bioavailability, complex extraction, and limited human data. Novel delivery systems, such as nanoemulsions and phospholipid-based carriers, offer potential solutions to enhance its bioavailability. As research advances, nobiletin emerges as a promising candidate for geroprotective therapy, warranting further investigation through well-designed clinical trials to extend healthspan and prevent age-associated pathologies. Full article

This study presents the first characterization of peel and leaf essential oils (EOs) from Citrus junos Sieb. ex Tanaka (yuzu) cultivated in Greece, evaluating seasonal maturation effects on their chemical profiles. EOs were extracted through hydrodistillation from samples harvested between September and November (stages H1–H3) and analyzed via GC-MS, identifying 32 and 38 volatile compounds in peel and leaf EOs, respectively. High yields were recorded for both peels (1.00–1.27%, peaking in H2) and leaves (0.28–0.39%, peaking in H1), exceeding values reported for East Asian and Mediterranean cultivars extracted through conventional methods (0.09–0.27% for peels; 0.04% for leaves). Peel EO matched the traditional yuzu chemotype, dominated by limonene (62.62–67.32%) and γ-terpinene (10.95–14.24%), but lacked β-phellandrene and contained higher amounts of thymol and sesquiterpenes. Early-stage peels (H1) were characterized by linoleic acid (2.26%), which cleared in subsequent months, indicating a marker for fruit immaturity. In contrast, leaf EO displayed a distinct profile dominated by β-phellandrene (27.92–29.60%), γ-terpinene (20.43–24.06%) and p-cymenene (8.95–10.86%) alongside 2,5-dimethoxy-p-cymene (2.92–3.54%). Late-stage harvests (H2 and H3) showed a more than three-fold increase in linalool (1.35% to 4.82%), enriching the oxygenated fraction and aroma quality. These results confirm that Mediterranean-grown yuzu maintains its aromatic identity while developing a high-yield regional profile, providing practical guidance for optimizing harvest timing across flavor, fragrance, and cosmetic applications. Full article

In this work we present an integrated market, experimental, technical and economic approach to citrus waste valorization based on the extraction of essential oils from orange, lemon, lime and tangerine peels using supercritical CO₂, comprising nine varieties of citrus fruits with high production in Brazil and varying harvesting seasons. This approach has been applied to such a variety of citrus waste as a novelty, allowing the observation of specific results for each kind of citrus fruit and a robust evaluation of the proposed process solution, which includes pre-treatment and extraction and may feature energy recovery. The varieties of fruits and volumes of production were selected based on a market assessment for a proposed capacity of approximately 500 kg/d of citrus waste in the extraction facility. Samples of citrus fruit waste were pre-processed by drying at 60 °C for 24 h and submitted to extraction using CO₂ at 150 bar and 35 °C for 30 min. The provisional results of the extractions (0.33% to 4.00% wt. oil yield) were used to perform the simulation of the extraction facility and estimate the cost of manufacture of essential oil, which ranged from US$26.70 to US$323.86/kg of extract, depending on the variety of citrus fruit. As an illustrative result of the application of the present screening approach, the cost of the production of essential oils from terra, bahia, seleta and lima oranges, as well as lemons, limes and tangerines, was compatible with the market price, while the costs of manufacturing pera and valencia orange essential oils were higher than the average price for cosmetic-grade and food-grade orange oil. The use of energy recovery in the CO₂ cycle would further increase the environmental sustainability of this strategy, with 55% lower energy consumption. Full article

Citrus processing generates massive volumes of citrus-processing by-products rich in polyphenols, pectin, and essential oils, yet most of these materials are disposed of with low-value utilization, causing biomass loss and environmental pressure. Physical-assisted extraction techniques represent promising strategies for recovering high-value bioactive components from citrus-processing by-products. This narrative review assesses mainstream conventional and physical-assisted extraction routes (acid-assisted, ultrasound-assisted, microwave-assisted, and supercritical CO₂ extraction) for phenolic compounds, pectin, and essential oils derived from citrus-processing by-products, summarizes optimal operational parameters, and compares their downstream food, biomaterial, and environmental remediation applications. Key findings demonstrate that ultrasound- and microwave-assisted extraction generally deliver higher extraction yields and better preservation of thermally sensitive bioactives relative to conventional reflux extraction; nevertheless, industrial-scale translation faces multiple bottlenecks, including high equipment investment, raw-material seasonal variability, incomplete solvent-recovery workflows, and scarce unified multi-dimensional evaluation benchmarks. Major limitations of existing research include the predominant focus on laboratory-scale yield optimization, with insufficient systematic quantitative comparisons covering energy consumption, product functional quality, life-cycle assessment (LCA), and techno-economic performance. Furthermore, thermal-driven oxidative degradation of d-limonene and polyphenols persists as a critical challenge hindering final product quality. Future perspectives highlight the need to establish standardized raw-material pretreatment protocols, combine chemical-based evaluation metrics and ISO 14040-compliant LCA frameworks to balance environmental benefits and economic profitability, and advance pilot-scale validation for hybrid coupled extraction processes. Key conclusions: although citrus-processing by-products possess enormous biorefinery potential, bridging laboratory-scale feasibility and industrial commercialization still requires joint progress in extraction-process optimization, safety validation, and circular-economy-oriented technical innovation. Full article

Olive pâté is a lipid-rich semi-solid product susceptible to oxidative deterioration during storage. This study investigated microencapsulated bergamot (Citrus bergamia) by-product extract (MBE) as a natural antioxidant for improving olive pâté stability. MBE, obtained by spray drying with 20% (w/w) maltodextrin, was incorporated at 2.5 or 5.0 g per 100 g of olives (OP_2.5 and OP₅), while a non-enriched formulation served as control (CTR). Samples were stored at 20 and 30 °C for 100 days and analysed for physicochemical, colour, phenolic, antioxidant, microbiological, sensory, and oxidative stability. Storage temperature and formulation significantly influenced quality evolution. At 30 °C, OP_2.5 showed the lowest total colour difference after 100 days (ΔE* = 3.29 versus 5.05 for CTR) and the highest final DPPH radical-scavenging activity. Both enriched formulations exhibited longer Oxitest induction periods than CTR at day 0 (26.53 and 25.33 vs. 19.85 h) and after 100 days at 30 °C (22.30 and 21.50 vs. 16.45 h). Microbial counts remained low, while sensory profiling indicated limited rancidity development and preservation of the main sensory characteristics. MBE effects were not proportional to the amount added, with OP2.5 providing the most balanced performance. These findings support MBE as a promising clean-label ingredient for improving olive pâté stability. Full article

The determination of pesticide residues in citrus fruits remains analytically challenging due to their high acidity and complex chemical compositions, which can compromise extraction efficiency and promote significant matrix effects, particularly for acidic compounds. In this study, an acidified acetonitrile-based QuEChERS method was developed and validated for the multiresidue determination of 136 pesticides in Tahiti lime (Citrus latifolia) using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS/MS). The proposed approach employs 1% formic acid in acetonitrile and omits the conventional clean-up step, aiming to improve analyte recovery and analytical throughput. Method validation was performed according to SANTE guidelines, demonstrating satisfactory linearity (R² ≥ 0.99 for all analytes), limits of quantification of 0.01 mg kg⁻¹, and recoveries within 70–120%, with relative standard deviations ≤ 20% for the vast majority of compounds. Notably, the method achieved consistent and reliable performance for 12 acidic pesticides, which are typically problematic in conventional QuEChERS approaches. Application to 22 real samples revealed the presence of 14 pesticide residues, with some compounds exceeding European Union (EU) maximum residue limits. The proposed method provides a simple, efficient, and robust alternative for comprehensive pesticide monitoring in citrus fruits, with particular advantages for the determination of acidic compounds in highly complex matrices. Full article

Fruit peels represent an abundant source of bioactive compounds with potential applications in green nanotechnology and plant protection. This study comparatively evaluated ethanolic extracts obtained from pomegranate (Punica granatum L.), orange (Citrus sinensis Osbeck), and persimmon (Diospyros kaki L.) peels and the corresponding silver nanoparticle (AgNP)-containing phytosynthesis preparations. The extracts were characterized for phytochemical and antioxidant properties and used for AgNP phytosynthesis, followed by UV-Vis, FTIR, BF-STEM, and EDS characterization. Their effects on Triticum aestivum L., Zea mays L., and Cucumis sativus L., as well as their antifungal activity against selected fungal strains, were comparatively assessed. Pomegranate peel extract showed the highest total phenolic content (147.52 mg g⁻¹ fw) and the strongest antifungal activity against Penicillium hirsutum, with an inhibition zone of 30 mm, followed by orange (27 mm) and persimmon (17.33 mm) peel extracts. The AgNP-containing preparations generally produced lower inhibition zones than the corresponding crude extracts. Antioxidant activity also decreased following phytosynthesis, with the most pronounced reduction observed for the orange peel system (90.72% to 35.17%). Plant responses were species- and treatment-dependent, with maize showing the lowest overall sensitivity to the investigated treatments. Overall, the results demonstrate that conversion of fruit peel extracts into AgNP-containing preparations does not necessarily enhance their biological activity and emphasize the importance of considering both the phytochemical characteristics of the starting extracts and the biological target when developing fruit-waste-derived systems for potential plant-protection applications. Full article

Pectin is a naturally occurring biopolymer extensively used for applications in the pharmaceutical, biotechnology, and food industries, and is abundantly present in lemon by-products. Although lemon peels represent a highly promising raw material, the structure of pectin is strongly influenced by extraction and drying processes, and the resulting attributes remain insufficiently understood. The present study systematically investigates the impact of conventional hot acid extraction using three different acidifying agents (citric, sulphuric, and hydrochloric) in combination with two drying techniques (oven-drying and freeze-drying) on the physicochemical, structural, thermal, and viscosity–shear rate properties of pectin obtained from lemon by-products (Citrus limon, Portuguese Eureka variety) following the prior recovery of bioactive compounds (essential oils and phenolic compounds). The results demonstrated that citric acid extraction followed by freeze-drying yielded the highest pectin recovery, at approximately 26.7%, highlighting the suitability of this approach for efficient by-product valorisation. Oven-dried pectins exhibited higher moisture contents (8.5–10%) and lower lightness values (L* = 57.02–65.67), indicating darker colouration compared to freeze-dried pectins (L* = 78.82–83.75). All extracted pectins presented a degree of esterification (DE ≥ 50%), classifying them as high-methoxyl pectins. The galacturonic acid (GalA) content ranged from 37.6 to 48.9% for oven-dried samples and increased to 44.1–58.6% for freeze-dried samples. Furthermore, pectin obtained from lemon by-products exhibited a well-defined structural organisation and enhanced thermal stability, especially for freeze-dried pectin samples, and suitable rheological properties, with no statistically significant variations observed between different acids or drying conditions, supporting its technological suitability for applications in the food, cosmetic, and pharmaceutical industries. Full article

Microalgae are recognized as sustainable biofactories for metabolites relevant to nutraceutical, pharmaceutical, and marine drug applications. Nannochloropsis salina is notable for its production of bioactive lipids, including the pharmaceutically relevant omega-3 eicosapentaenoic acid (EPA). Here, we evaluated orange peel extract (OPE), a citrus by-product, as a substrate for mixotrophic cultivation of N. salina within a bioeconomy framework. OPE supplementation triggered dose-dependent physiological responses. Among the tested OPE concentrations, 5% supplementation resulted in the highest total fatty acid content, increasing fatty acids from 24.4% (control) to 30.6% and EPA from 6.4% to 9.8%, whereas 10% OPE maintained biomass pigmentation. Higher OPE levels enhanced antioxidant potential, raising total antioxidant capacity from 4.6 (control) to 6.7 mg/g vitamin C equivalents (with 10% OPE), while the highest concentrations induced metabolic stress, reducing biomass and altering lipid composition. Fourier transform infrared spectroscopy analyses revealed biochemical adjustments consistent with metabolic reorganization, including increased intensities of the amide I and II bands associated with protein-rich structures. Overall, OPE emerges as a cost-effective supplement capable of modulating the biochemical quality of N. salina while valorizing agro-industrial residues. The increases in EPA and antioxidant capacity support the potential of OPE-supplemented cultures as a platform for the production of marine-derived bioactive compounds. Full article

Finger lime (Citrus australasica) is an emerging high-value fruit species, yet the chemical profiles of Mediterranean-cultivated varieties remain underexplored. This study presents the first chemical characterization of two finger lime varieties, Pink Ice and Green Crystal, grown in Greece, providing the first report on the volatile and non-volatile composition of Green Crystal. Peel essential oils were extracted and analyzed through GC-MS across two harvesting periods (H1 and H2), while methanolic extracts were assessed for their total phenolic content (TPC) and DPPH radical scavenging activity. Non-volatile untargeted profiling was performed on stage H1 extracts using UHPLC-MS/MS. The results revealed a significant chemical divergence between the varieties. Green Crystal exhibited an unprecedented p-cymene/β-phellandrene/citronellal/citronellol volatile chemotype, while Pink Ice displayed a limonene/p-cymene/sabinene/terpinen-4-ol chemotype. Maturity of the fruit significantly influenced monoterpene distribution, with an increase in monoterpene hydrocarbons at the expense of oxygenated derivatives. TPC peaked at stage H1, showing a significant maturity-dependent decline in both varieties, whereas DPPH radical scavenging capacity remained stable across both harvests. UHPLC-MS/MS analysis annotated 58 metabolites, including several compounds reported for the first time in the species. Variety-specific tendencies were observed, with Pink Ice exhibiting greater diversity in flavanones, flavonols, and simple coumarins, whereas Green Crystal exhibited greater diversity in flavones, furanocoumarins, and HMG (hydroxy-3-methylglutaric acid)-flavonoid conjugates. These findings demonstrate that variety selection and harvesting timing are critical parameters for optimizing the commercial and bioactive value of Mediterranean-grown finger lime, highlighting the significant potential for expanded cultivation in the region. Full article

The development of alcohol-free spirits with attractive sensory properties remains a major challenge due to the absence of ethanol, which plays a key role in the extraction, stabilization, and perception of aroma compounds. In this study, the aromatic profile of dealcoholized gin (0.0% alcohol) was improved through post-production maceration with raspberry (Rubus idaeus L.) and orange (Citrus sinensis L.), evaluating the effect of fruit type and maceration time (7 and 14 days) on both volatile composition and sensory attributes. Volatile compounds were analyzed by GC–MS, while sensory characterization was performed using Quantitative Descriptive Analysis (QDA). Fruit type and maceration time significantly affected the volatile composition and specific fruit-related sensory descriptors, particularly orange and red fruit notes (p < 0.05), while traditional gin descriptors remained comparatively stable. Orange promoted citrus-related notes, particularly after short maceration times, whereas raspberry contributed to the development of red fruit sensory notes, which were more clearly perceived after 14 days. Maceration time influenced aroma development in a compound-dependent manner: shorter times favored the presence of highly volatile terpenes, while longer maceration modified the sensory balance and contributed to greater aroma integration, although some volatile compounds decreased over time. The study demonstrates that controlled maceration with orange and raspberry is an effective strategy for improving the aroma profile and sensory quality of dealcoholized gin (0.0% alcohol). Full article

To address the evaluation requirements for agricultural robotic harvesting, this work presented a fruit-grasping assessment system based on tactile fusion analysis. Four piezoresistive pressure sensors were symmetrically integrated into the inner surfaces of a flexible gripper. A signal-conditioning circuit and a data acquisition module transmitted tactile signals to a Transformer–Mamba fusion network for feature extraction and target classification. After being trained on a dataset comprising 300 samples, the model extracted deep tactile features to distinguish among three target categories: citrus fruits, branches, and leaves. Classification outputs generated control commands for a robotic manipulator, enabling obstacle-avoidance retraction and precise harvesting operations. Experimental evaluations, conducted in both indoor and outdoor environments, demonstrated a target recognition accuracy of 93.12%. The manipulator response time was below 0.5 s, and the operational success rate was 90%. The proposed sensing system and algorithmic framework showed strong adaptability and supported quantitative assessment of grasping performance. The fruit detachment, compression damage, and plant-collision risks were effectively reduced while operational stability and harvesting efficiency improved. Full article