Citrus peels waste as a source of value-added compounds: Extraction and quantification of bioactive polyphenols

Silica and mesoporous silica nanoparticles display effective insecticidal effect and augment plant defense responses

The polyphagous insect pest, Spodoptera litura displays insecticide resistance that requires new control tactics. In this context, inorganic silica nanoparticles (SiNPs) and mesoporous silica nanoparticles (MSNPs) were studied for their insecticidal activity and their effects on the plant defense responses. The synthesized silica (SiNPs,160 nm size) and mesoporous silica (MSNPs,100 nm size) nanoparticles showed high insecticidal effect of against S. litura larvae with 73.0 and 80.0 % mortalities, respectively at low nanoparticles concentration (1 μg). Administration of NPs by feeding enhanced the larval gut uptake and caused a significant ∼14.9- to 12.7-fold reduction in lactate dehydrogenase activity for SiNPs and MSNPs, respectively. Efficient uptake of fluorescent NPs was illustrated in columnar larval gut cells. Feeding of SiNPs and MSNPs led to a significant reduction in larval weight (2.9- and 3.4-fold, respectively) due to their antifeedant effect which was positively correlated to larval mortalities. Both NPs exhibited negligible cytotoxicity in vitro. Furthermore, application of rhodamine B fluorescence-tagged NPs on soyabean leaves showed NPs presence on the leaf surfaces and were not internalized by the leaf. Moreover, the electromechanical plant responses to NPs application displayed increased localized signal durations (>2-fold). Additionally, SiNPs and MSNPs treatments significantly upregulated the 12-oxophytodienoate reductase plant jasmonic acid defense pathway gene expression (2.7- and 1.4-fold, respectively) that led to enhanced jasmonic acid contents. Application of SiNPs and MSNPs at low concentrations achieved insecticidal effect against S. litura and enhanced the plant defense responses against pest. Silica nanoparticles have potential in safe and effective management of S. litura.

Fermentation characteristics of pectin-derived oligosaccharides from enzyme treated side streams of citrus processing

This study explored the conversion of citrus juice side streams into fermentable oligosaccharides for potential gut health benefits. Alcohol washed, insoluble lemon peel waste was enzymatically treated using technical pectinolytic enzyme preparations, yielding mixtures of galactose- arabinose- and either methyl-esterified or non-methyl-esterified galacturonic acid oligosaccharides (OS) with a Δ4,5-unsaturated non-reducing end resulting in mixtures of pectin-derived OS: POS and POSNME. Both mixtures were completely fermented during in vitro batch fermentation by proximal and distal microbiota of three healthy adult donors. Fermentation by distal and proximal microbiota resulted in similar methyl-ester-dependent mechanisms of POS utilization, yielding health beneficial acetate, propionate and butyrate in significant amounts. Arabinose-, galactose- and non-methyl-esterified Δ4,5-unsaturated galacturonic acid OS were utilized significantly faster by the distal and proximal microbiota of donors 1 and 2 compared to methyl-esterified Δ4,5-unsaturated galacturonic acid OS, suggesting methyl-esterification of Δ4,5-unsaturated galacturonic acid oligosaccharides as a substantial regulator of POS fermentability. The findings presented in this manuscript suggest that carbohydrate molecular structure and availability, rather than microbiota composition, determine carbohydrate fermentation patterns along the colon, emphasizing that the consumption of differently fermentable fiber is essential to promote gut health along the colon.

Optimization of microwave-assisted extraction using response surface methodology and HPLC-DAD phenolic compounds quantification from Hylocereus undatus peel and pulp cultivated in Tunisia

The present study aimed to optimize the microwave-assisted extraction process for both the peel and pulp of Hylocereus undatus (white dragon fruit) cultivated in Tunisia, using response surface methodology. Total phenolic content, total flavonoid content, FRAP (ferric reducing antioxidant power), and DPPH (1,1-diphenyl-2-picrylhydrazyl) antioxidant activities were optimized. A central composite design (CCD) was applied, considering three key variables: extraction time, extraction temperature, and liquid-to-solid ratio. The optimized extraction parameters for Hylocereus undatus peel and pulp were determined respectively (9.57 min, 42.20 °C and 27.79 mL/g) and (10.08 min, 40.84 °C and 31.52 mL/g). The main phenolic compounds identified in Hylocereus undatus peel and pulp extracts using HPLC-DAD were chlorogenic and caffeic acids and rutin, quercetin, luteolin-7-O-glucoside as flavonoids. Therefore, this research has revealed the potential of a sustainable and eco-friendly process hold promise a directional option and encouraging a circular economy approach for industrial production of antioxidant-rich Hylocereus undatus extracts.

Integrated Biotechnological Strategies for the Sustainability and Quality of Mediterranean Sea Bass (Dicentrarchus labrax) and Sea Bream (Sparus aurata)

This review examines the current state of the supply chain management for Dicentrarchus labrax (sea bass) and Sparus aurata (sea bream), two key commercial fish species in the Mediterranean. It provides a comprehensive analysis of sustainable innovations in aquaculture, processing, and packaging, with particular attention to circular economy-based biopreservation techniques. A major focus is on the Integrated Multi-Trophic Aquaculture (IMTA) system, an advanced farming approach that enhances sustainability, promotes circular resource utilization, and improves fish welfare. By fostering ecological balance through the co-cultivation of multiple species, IMTA contributes to the overall quality of fish products for human consumption. Beyond aquaculture, the review addresses the critical challenge of food loss, which stems from the high perishability of fish during storage and processing. In this regard, it highlights recent advancements in biopreservation strategies, including the application of antagonistic microorganisms, their metabolites, and plant-derived extracts. Particular attention is given to the development of edible antimicrobial films, with a focus on the valorization of citrus processing by-products for their production. By centering on innovations specific to the Mediterranean context, this review underscores that a holistic, integrative approach to supply chain management is essential for transitioning the aquaculture sector toward greater efficiency and sustainability.

Polyphenol extraction from industrial water by-products: a case study of the ULTIMATE project in the fruit processing industry

This study investigates the sustainable management and utilization of water resources in the fruit processing industry, focusing on a case study from the EU-funded ULTIMATE project. Conducted in a juice factory in Nafplio, Greece, the primary objective is to explore the recovery of polyphenols from water by-product streams generated during orange juice production. The research aims to evaluate the effectiveness of a mobile wastewater treatment unit in selectively adsorbing polyphenols onto a polymeric resin. The following three extraction methods are compared: conventional solvent extraction, subcritical water extraction (SWE), and supercritical CO2 extraction (SFE). To determine the most efficient extraction method, the polyphenol profiles of the extracts were analyzed using UHPLC-Q-Orbitrap-MS/MS, identifying flavonoids, terpenes, coumarins, and anthocyanins. SFE not only was the most efficient method but provided the most diverse and abundant profile. The research highlights the potential of converting industrial by-products that would otherwise be treated as wastewater, into valuable resources that generate revenue, promote circular economy practices, and enhance sustainability in the fruit and vegetable processing sector. The economic viability of polyphenol extraction is also discussed, emphasizing its significance and impact on various industries. The findings support integrating advanced extraction technologies to maximize resource recovery and minimize environmental impact.

Metabolomics combined with biochemical analyses revealed phenolic profiles and antioxidant properties of rapeseeds

Phenolic compounds, one of the most crucial lipid concomitants in rapeseed, have garnered heighten attention due to their numerous health benefits. Therefore, efficiently characterizing the phenolic profile of rapeseed is paramount for discerning their potential bioactivities. This study employed untargeted metabolomics in conjunction with molecular networking to trace the phenolic composition across three rapeseed genotypes. A total of 117 phenolic compounds were identified in rapeseed by mass spectrometry under positive and negative ionization modes, including 36 flavonoids, 23 coumarins, 12 phenolic acids, 10 lignans, 4 stilbenes, 4 diarylheptanes, 1 tannin, and several other phenolic constituents. Biochemical analyses revealed that Brassica napus rapeseed typically exhibited the highest total phenolic content and total flavonoid content as well as the strongest antioxidant capacity among three rapeseed genotypes. Through correlation analysis, 17 potential antioxidant phenolic compounds were tentatively screened from rapeseed, supporting the development and utilization of natural antioxidants from rapeseed.

Citrus Flavonoids as Antimicrobials

Citrus flavonoids are highly bioactive compounds exerting numerous health benefits including anticancer, antioxidant, antimicrobial, anti-inflammatory, mitoprotective, and neuroprotective activity. Research on their broad-scope bioactivity experienced a renaissance in the early 2000s, and further accelerated after COVID-19, including research on their antimicrobial properties. Summarizing selected research achievements on the antimicrobial activity of the main Citrus flavonoids, this study aims to provide a unified picture on the antimicrobial properties of these valued compounds that will hopefully assist in the development of flavonoid-based antimicrobials, including antibacterial treatments suitable for clinical use minimizing antimicrobial resistance.

Fumaria officinalis Dust as a Source of Bioactives for Potential Dermal Application: Optimization of Extraction Procedures, Phytochemical Profiling, and Effects Related to Skin Health Benefits

Fumaria officinalis (fumitory), in the form of dust, was employed as a source of bioactive extracts whose chemical profile and biological potential were investigated. According to the results of the optimization of the extraction protocol, the extract with the highest polyphenol yield was prepared using fumitory dust under the optimal conditions determined using the statistical tool, 23 full factorial design: 50% ethanol and a 30:1 mL/g ratio during 120 s of microwave extraction (22.56 mg gallic acid equivalent/g of plant material). LC-MS and spectrophotometric/gravimetric analyses quantified the polyphenol, flavonoid, tannin, alkaloid, and protein contents. Caffeoylmalic acid, quercetin dihexoside, quercetin pentoside hexoside, rutin, and methylquercetin dihexoside were the most dominant compounds. The highest total flavonoid, condensed tannin, alkaloid, and protein yields were determined in the extract prepared using microwaves. In addition to the proven antioxidant potential, in the present study, the anti-inflammatory activity of fumitory extracts is also proven in the keratinocyte model, as well as a significant reduction of H2O2-induced reactive oxygen species production in cells and the absence of keratinocyte cytotoxicity. Thus, detailed chemical profiles and investigated biological effects related to skin health benefits encourage the potential application of fumitory dust extracts in dermo-cosmetic and pharmaceutical preparations for dermatological circumstances.

Transforming lemon Peel into a sustainable reservoir of bioactives: A green osmotic dehydration strategy

Osmotic dehydration (OD) is a sustainable alternative, offering reduced energy consumption compared to traditional drying approaches. This study investigates the role of OD in stabilizing bioactive compounds in lemon peel, fostering sustainable citrus by-product applications. Employing Response Surface Methodology (RSM) framework, pivotal variables-temperature (30-60 °C), exposure time (60-180 min), and sucrose concentration (50-70°Brix)-were optimized to enhance water loss (WL) and solid gain (SG) while safeguarding bioactive retention. The optimal conditions (58.92 °C, 70°Brix, 159 min) yielded a WL of 3.4 g/g, SG of 1.5 g/g, and high sensory acceptability. The OD treated lemon peel powder exhibited substantial retention of bioactive compounds, including ascorbic acid (4.1 mg/g) and total phenols (2.3 mg gallic acid/g), surpassing untreated controls. This enhanced bioactive profile underscores its potential as a sustainable and functional ingredient in nutraceutical applications.

Exploring Antimicrobial Compounds from Agri-Food Wastes for Sustainable Applications

Transforming agri-food wastes into valuable products is crucial due to their significant environmental impact, when discarded, including energy consumption, water use, and carbon emissions. This review aims to explore the current research on the recovery of bioactive molecules with antimicrobial properties from agri-food waste and by-products, and discusses future opportunities for promoting a circular economy in its production and processing. Mainly, antibacterial molecules extracted from agri-food wastes are phenolic compounds, essential oils, and saponins. Their extraction and antimicrobial activity against a wide spectrum of bacteria is analyzed in depth. Also, their possible mechanisms of activity are described and classified based on their effect on bacteria, such as the (i) alteration of the cell membrane, (ii) inhibition of energy metabolism and DNA synthesis, and iii) disruption of quorum sensing and biofilm formation. These bioactive molecules have a wide range of possible applications ranging from cosmetics to food packaging. However, despite their potential, the amount of wastes transformed into valuable compounds is very low, due to the high costs relating to their extraction, technical challenges in managing supply chain complexity, limited infrastructure, policy and regulatory barriers, and public perception. For these reasons, further research is needed to develop cost-effective, scalable technologies for biomass valorization.

Recovery, Bioactivity, and Utilization of Bioactive Phenolic Compounds in Citrus Peel

Citrus peels are rich in bioactive phenolic compounds with various health effects including antioxidant, antiobesity, antiinflammatory, antihypertensive, antihypercholesterolemic, antimicrobial, antidiabetic, and anticarcinogenic activities. Both extractable and nonextractable phenolics are present in significant amounts in Citrus peel with diverse bioactivities. While extractable phenolics can be recovered from the fruit peels by conventional extraction methods, nonextractable phenolics remaining in the residues must be released from the cell matrix first by hydrolysis with acid, alkali, or enzymes. Novel processing technologies can help in improvement of extraction efficiency. Extreme process or medium conditions degrade phenolics and their bioactivity where encapsulation can be applied to improve their stability, solubility, and bioactivity. Citrus peel powder including ascorbic acid and dietary fiber besides phenolics or extracts therefrom can be used as functional food ingredients to extend shelf life and provide health benefits. In addition, phenolic extracts can be used as antioxidant and antimicrobial agents in active food packaging applications. Phenolic extracts have also a potential to be used as nutraceuticals and pharmaceuticals. In this review, phenolic compounds in different forms in Citrus peels, their recovery, bioactivity and possible applications for upcycling in the industry are presented.

Green technologies for extracting plant waste functional ingredients and new food formulation: A review

Nowadays, there is a growing interest in food waste recovery by both consumers and companies. Food waste of plant origin is a source of bioactive compounds, such as phenolic acids, anthocyanins, flavonoids, phytosterols, carotenoids, and tocopherols, with well-known antioxidant, anti-glycemic, and antimicrobial properties. The use of green and sustainable technologies to recover bioactive compounds from food waste is a possible solution to valorize waste following the principles of green chemistry. Furthermore, today's consumers are more attracted, informed, and aware of the benefits associated with the consumption of functional foods, and with this in mind, the use of extracts rich in beneficial compounds obtained by green technologies from food waste can be a valid alternative to prepare functional foods. In this review, the recovery of polyphenols and fibers with green technologies from food waste for the formulation of functional foods was presented.

Influence of ZnSO4 and Methyl Jasmonate on the Metabolites and Bioactivity Present in Lemon-Fruit Membrane Vesicles

Membrane vesicles isolated from vegetable tissues have shown promise in encapsulation technologies used in industries like food and cosmetics, offering innovative approaches to product development. However, their associated linked metabolites have not been studied. Lemon vesicle research not only adds value to the lemon crop (Citrus × limon L.), one of the most widely cultivated fruit trees in the world, is a source of bioactive compounds such as phenolics and organic acids. In this study, the influence of elicitation with ZnSO4 and methyl jasmonate, which modulate the bioactive metabolites, on fruit membrane vesicle bond metabolites was studied. The study showed that foliar application of ZnSO4 increased phenolic compounds as caffeic, sinapic, and chlorogenic acids and the flavonoid hesperidin by about 20% in lemons. Furthermore, a clear interaction between vesicles and citrate and ascorbate that were increased by methyl jasmonate were associated with their higher bioactivity. This was related to the double intrinsic in vitro antioxidant activities of these vesicles.

Exploring chemical properties of essential oils from citrus peels using green solvent

The research explored the chemical characteristics of essential oils (EOs) extracted from the peels of four citrus fruits grown in northeastern Peru (lime, sweet lemon, mandarin and orange). The essential oils were extracted by hydrodistillation using a green solvent, and subsequently, their physicochemical profile, bioactive, heat capacity, and RAMAN mapping were determined; in addition, the volatile composition was determined by gas chromatography (GC-MS), and the main phenols by liquid chromatography (UHPLC). The results evidenced that sweet lemon and mandarin essential oils had higher antioxidant activity (1592.38 and 1216.13 μmol TE/g) and total phenolic content (680.78 and 420.28 mg GAE/g). In contrast, sweet lemon peel essential oil had the highest total flavonoid content (23.18 mg QE/g). D-limonene was the most abundant aromatic compound in orange (>67 %), mandarin (>70 %), and sweet lemon (>72 %) EOs; however, in the lime, it was the lowest (37 %). The most abundant component was the cyclobutane, 1,2-bis(1-methylethylethylenyl)-, trans- (32 %).

Insights on the Extraction and Analysis of Phenolic Compounds from Citrus Fruits: Green Perspectives and Current Status

Citrus fruits (CF) are highly consumed worldwide, fresh, processed, or prepared as juices and pies. To illustrate the high economic importance of CF, the global production of these commodities in 2021 was around 98 million tons. CF's composition is considered an excellent source of phenolic compounds (PC) as they have a large amount and variety. Since ancient times, PC has been highlighted to promote several benefits related to oxidative stress disorders, such as chronic diseases and cancer. Recent studies suggest that consuming citrus fruits can prevent some of these diseases. However, due to the complexity of citrus matrices, extracting compounds of interest from these types of samples, and identifying and quantifying them effectively, is not a simple task. In this context, several extractive and analytical proposals have been used. This review discusses current research involving CF, focusing mainly on PC extraction and analysis methods, regarding advantages and disadvantages from the perspective of Green Chemistry.

Flavonoid Profiles in the Pulp of Different Lemon Cultivars and Their Antioxidant Activity Based on UPLC-Q-TOF-MS

Previous studies have indicated that there may be differences among the varieties of lemon flavonoids, but the details have not yet been made clear, which limits the comprehensive use of different cultivated lemon varieties. In this study, ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS) and ultraviolet-visible spectroscopy (UV-Vis) were used to investigate the types and contents of flavonoids in the flesh of the main cultivated variety (Eureka) and five common lemon varieties, as well as their in vitro antioxidant activity. A total of 21 compounds were identified, five of which were common compounds. Among them, Verna, Lisbon, and Bearss each have characteristic components that can serve as potential criteria for variety identification. Each of the six varieties of lemon has strong antioxidant activity. The antioxidant activity of different lemon varieties is related to flavonoids. Therefore, Eureka and the other five varieties of lemon are good natural antioxidants, and the cultivation and industrial production of lemons should consider the needs and selection of suitable varieties.

Chemometric discrimination of eight citrus plants utilizing chromatographic and spectroscopic techniques and insights into their biological potentials

Citrus sinensis balady orange, C. sinensis navel orange, C. paradisi, C. limon, C. sinensis bloody orange, C. sinensis sweet orange, C. aurantium var. amara and C. reticulata were successfully discriminated using chromatographic and spectroscopic techniques coupled with chemometrics. Ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) managed to discriminate the alcohol extract samples to six and five clusters respectively on exposing the obtained data to Principle component analysis (PCA). High performance liquid chromatography (HPLC) was utilized for differentiating the different samples based upon their rutin content where C. aurantium demonstrated the highest rutin content (0.795 mg/mL). LC-ESI-MS led to the identification of 35 compounds belonging mainly to flavonoids and limonoids. In vitro biological investigations including DDPH, ABTS, FRAP and enzyme inhibitory activities revealed the promising antioxidant, neuroprotective, anti-hyperglycaemic and skin-lightning potentials of citrus samples that were correlated with the total phenol and flavonoid contents. In silico ADME/TOPKAT reflected the acceptable pharmacokinetic, pharmacodynamic and toxicity properties of the identified secondary metabolites.

A comparative metabolomic investigation of different sections of Sicilian Citrus x limon (L.) Osbeck, characterization of bioactive metabolites, and evaluation of in vivo toxicity on zebrafish embryo

Citrus fruits are a diverse and economically important group of fruit crops known for their distinctive flavors and high nutritional value. Their cultivation and consumption contribute significantly to the global agricultural economy and offer a wide range of health benefits. Among the genetic diversity of citrus species, Citrus x limon (L.) Osbeck is particularly relevant due to its chemical composition and potential health benefits. Two cultivars from the Sicily region (southern Italy) were compared for their phenolic content and preliminary antioxidant activity to select the distinctive extract with potential biological activity. A detailed characterization revealed the occurrence of phenolics, coumarins, and flavonoids. The quantification of metabolites contained in the selected extract was performed by an ultrahigh-performance liquid chromatographic method coupled with an ultraviolet detector. Different concentrations were tested in vivo through the fish embryo acute toxicity test, and the 50% lethal dose of 107,833 µg mL-1 was calculated. Finally, the effect of the extract on hatching was evaluated, and a dose-dependent relationship with the accelerated hatching rate was reported, suggesting a Femminello Zagara Bianca green peel upregulating effect on the hatching enzymes. PRACTICAL APPLICATION: Citrus fruits and their products continue to be one of the natural food sources with the highest waste output. In this study, we demonstrate how food industry waste, particularly lemon peel, is rich in bioactive compounds with anti-inflammatory and antioxidant properties that may be used in the nutraceuticals industry.

A Comprehensive Analytical Review of Polyphenols: Evaluating Neuroprotection in Alzheimer's Disease

Alzheimer's Disease (AD), a prevalent neurodegenerative disorder, is the primary cause of dementia. Despite significant advancements in neuroscience, a definitive cure or treatment for this debilitating disease remains elusive. A notable characteristic of AD is oxidative stress, which has been identified as a potential therapeutic target. Polyphenols, secondary metabolites of plant origin, have attracted attention due to their potent antioxidant properties. Epidemiological studies suggest a correlation between the consumption of polyphenol-rich foods and the prevention of chronic diseases, including neurodegenerative disorders, which underscores the potential of polyphenols as a therapeutic strategy in AD management. Hence, this comprehensive review focuses on the diverse roles of polyphenols in AD, with a particular emphasis on neuroprotective potential. Scopus, ScienceDirect, and Google Scholar were used as leading databases for study selection, from 2018 to late March 2024. Analytical chemistry serves as a crucial tool for characterizing polyphenols, with a nuanced exploration of their extraction methods from various sources, often employing chemometric techniques for a holistic interpretation of the advances in this field. Moreover, this review examines current in vitro and in vivo research, aiming to enhance the understanding of polyphenols' role in AD, and providing valuable insights for forthcoming approaches in this context.

Optimization of Production Parameters for Fabrication of Gum Arabic/Whey Protein-Based Walnut Oil Loaded Nanoparticles and Their Characterization

The encapsulation of fatty acids, including walnut oil, within complexes is a promising strategy to address challenges, for instance, low water solubility and susceptibility to oxidation while incorporating these oils into food products. Additionally, encapsulation can effectively mask undesirable odor and flavor. The current study focuses on the optimization of walnut oil nanoparticles (WON) using complexes fabricated from gum arabic and whey protein by applying a response surface methodology. The impact of three different independent variables were determined, such as surfactant mixture (33-66%), walnut oil (5-25%), and sonication time (60-300 s), under three distinct desired conditions (low, medium, and high) on four different responses, i.e., particle size, polydispersity index (PDI), moisture level, and encapsulation efficiency (EE). The findings of the present study indicate that the point prediction-based WON resulted in significantly low particle size (82.94 nm), PDI (0.19), moisture content (3.49%), and high EE (77.26%). Fourier transform infrared spectroscopy (FTIR) study demonstrated the successful encapsulation of walnut oil and wall material into nanocapsules. Differential scanning calorimetry (DSC) verified the improved thermal stability property of WON after incorporation, and scanning electron microscopy (SEM) indicated that the WON had relatively fragile and smooth surfaces, along with the presence of few porous structures. The recorded experimental data from the existing study showed that the developed formulation of WON was potentially useful as a value-added ingredient for food industries.

Unveiling the Chemistry of Citrus Peel: Insights into Nutraceutical Potential and Therapeutic Applications

The recent millennium has witnessed a notable shift in consumer focus towards natural products for addressing lifestyle-related disorders, driven by their safety and cost-effectiveness. Nutraceuticals and functional foods play an imperative role by meeting nutritional needs and offering medicinal benefits. With increased scientific knowledge and awareness, the significance of a healthy lifestyle, including diet, in reducing disease risk is widely acknowledged, facilitating access to a diverse and safer diet for longevity. Plant-based foods rich in phytochemicals are increasingly popular and effectively utilized in disease management. Agricultural waste from plant-based foods is being recognized as a valuable source of nutraceuticals for dietary interventions. Citrus peels, known for their diverse flavonoids, are emerging as a promising health-promoting ingredient. Globally, citrus production yields approximately 15 million tons of by-products annually, highlighting the substantial potential for utilizing citrus waste in phyto-therapeutic and nutraceutical applications. Citrus peels are a rich source of flavonoids, with concentrations ranging from 2.5 to 5.5 g/100 g dry weight, depending on the citrus variety. The most abundant flavonoids in citrus peel include hesperidin and naringin, as well as essential oils rich in monoterpenes like limonene. The peel extracts exhibit high antioxidant capacity, with DPPH radical scavenging activities ranging from 70 to 90%, comparable to synthetic antioxidants like BHA and BHT. Additionally, the flavonoids present in citrus peel have been found to have antioxidant properties, which can help reduce oxidative stress by 30% and cardiovascular disease by 25%. Potent anti-inflammatory effects have also been demonstrated, reducing inflammatory markers such as IL-6 and TNF-α by up to 40% in cell culture studies. These findings highlight the potential of citrus peel as a valuable source of nutraceuticals in diet-based therapies.

Integrated HS-GC-IMS and UPLC-Q-Orbitrap HRMS-based metabolomics revealed the characteristics and differential volatile and nonvolatile metabolites of different citrus peels

Citrus is an important genus in the Rutaceae family, and citrus peels can be used in both food and herbal medicine. However, the bulk of citrus peels are discarded as waste by the fruit processing industry, causing environmental pollution. This study aimed to provide guidelines for the rational and effective use of citrus peels by elucidating the volatile and nonvolatile metabolites within them using metabolomics based on headspace-gas chromatography-ion mobility spectrometry and ultra-high-performance liquid chromatography-Q-Orbitrap high-resolution mass spectrometry. In addition, the antioxidant activities of the citrus peels were evaluated using DPPH radical scavenging, ABTS radical scavenging, and ferric reducing antioxidant power. In total, 103 volatile and 53 nonvolatile metabolites were identified and characterized. Alcohols, aldehydes, and terpenes constituted 87.36% of the volatile metabolites, while flavonoids and carboxylic acids accounted for 85.46% of the nonvolatile metabolites. Furthermore, (Z)-2-penten-1-ol, L-pipecolinic acid, and limonin were identified as characteristic components of Citrus reticulata Blanco cv. Ponkan (PK), C. reticulata 'Unshiu' (CLU), and C. reticulata 'Wo Gan' (WG), respectively. Principal component analysis and partial least squares discriminant analysis indicated that C. reticulata Blanco 'Chun Jian' (CJ), PK, CLU, and C. reticulata 'Dahongpao' (DHP) were clustered together. DHP is a traditional Chinese medicine documented in the Chinese Pharmacopoeia, suggesting that the chemical compositions of CJ, PK, and CLU may also have medicinal values similar to those of DHP. Moreover, DHP, PK, C. reticulata 'Ai Yuan 38'(AY38), CJ, C. reticulata 'Gan Ping'(GP), and C. reticulata 'Qing Jian'(QJ) displayed better antioxidant activities, recommending their use as additives in cosmetics and food. Correlation analysis suggested that some polyphenols including tangeritin, nobiletin, skullcapflavone II, genistein, caffeic acid, and isokaempferide were potential antioxidant compounds in citrus peel. The results of this study deepen our understanding of the differences in metabolites and antioxidant activities of different citrus peel varieties and ultimately provide guidance for the full and rational use of citrus peels.

Comparative Evaluation of Secondary Metabolite Chemodiversity of Citrus Genebank Collection in Greece: Can the Peel be More than Waste?

Citrus fruits are among the most economically important crops in the world. In the global market, the Citrus peel is often considered a byproduct but substitutes an important phenotypic characteristic of the fruit and a valuable source of essential oils, flavonoids, carotenoids, and phenolic acids with variable concentrations. The Mediterranean basin is a particularly dense area of autochthonous genotypes of Citrus that are known for being a source of healthy foods, which can be repertoires of valuable genes for molecular breeding with the focus on plant resistance and quality improvement. The scope of this study was to characterize and compare the main phenotypic parameters (i.e., peel thickness, fruit volume, and area) and levels of bioactive compounds in the peel of fruits from the local germplasm of Citrus in Greece, to assess their chemodiversity regarding their polyphenolic, volatile, and carotenoid profiles. A targeted liquid chromatographic approach revealed hesperidin, tangeretin, narirutin, eriocitrin, and quercetin glycosides as the major polyphenolic compounds identified in orange, lemon, and mandarin peels. The content of tangeretin and narirutin followed the tendency mandarin > orange > lemon. Eriocitrin was a predominant metabolite of lemon peel, following its identification in lower amounts in mandarin and at least in the orange peel. For these citrus-specific metabolites, high intra- but also interspecies chemodiversity was monitored. Significant diversity was found in the essential oil content, which varied between 1.2 and 3% in orange, 0.2 and 1.4% in mandarin, and 0.9 and 1.9% in lemon peel. Limonene was the predominant compound in all Citrus species peel essential oils, ranging between 88 and 93% among the orange, 64 and 93% in mandarin, and 55 and 63% in lemon cultivars. Carotenoid analysis revealed different compositions among the Citrus species and accessions studied, with β-cryptoxanthin being the most predominant metabolite. This large-scale metabolic investigation will enhance the knowledge of Citrus peel secondary metabolite chemodiversity supported by the ample availability of Citrus genetic resources to further expand their exploitation in future breeding programs and potential applications in the global functional food and pharmaceutical industries.

Insights into metabolic characteristics and biological activity changes in Zangju (Citrus reticulata cv. Manau Gan) peel at different maturity stages through UPLC-MS/MS-based metabolomics

In this study, comprehensive and systematic nontargeted metabolomics analysis was performed with the metabolites of Zangju peel (Citrus reticulata cv. Manau Gan, CRZP, which has been cultivated for over 400 years in Derong County, China.) at four different mature stages. A total of 1878 metabolites were identified, among which flavonoids were the most abundant (62.04 %), and identified 62 key differential metabolites significantly affected by maturity. Based on biological activity measurements, CRZP showed better antioxidant activity, lipase inhibition ability, inhibition of adipogenic differentiation in 3TT-L1 cells and promotion of lipid metabolism, with the biological activity of CRZP at different maturity stages being associated with key differential metabolite. Thus, CRZP is natural antioxidants and possess anti-obesity potential, and industrial production needs to consider the Maturity stage of its collection.

Bioactives from citrus food waste: types, extraction technologies and application

The Citrus fruits belong to the category where the groups of fruits are recognized to be an admirable repository of bioactive elements and phytochemical constituents, with strong biological potentials. The prominent use of Citrus fruits for nutrition as well as food processing has led to the release of a large amount of waste into the environment and surrounding, and it simultaneously burdens the nature and existence of many organisms including the human population. In order to rectify such consequences, the reuse of food waste from citrus for various advantageous effects. In this regard, the first part of the article primarily focussed on the various strategies available for the extraction of chemical elements from citrus waste and the remaining strand of the article focussed on the various bioactive compounds with special reference to their pharmacological as well as the medicinal benefits and future prospects.

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Hesperidin from Orange Peel as a Promising Skincare Bioactive: An Overview

The pursuit for better skin health, driven by collective and individual perceptions, has led to the demand for sustainable skincare products. Environmental factors and lifestyle choices can accelerate skin aging, causing issues like inflammation, wrinkles, elasticity loss, hyperpigmentation, and dryness. The skincare industry is innovating to meet consumers' requests for cleaner and natural options. Simultaneously, environmental issues concerning waste generation have been leading to sustainable strategies based on the circular economy. A noteworthy solution consists of citrus by-product valorization, as such by-products can be used as a source of bioactive molecules. Citrus processing, particularly, generates substantial waste amounts (around 50% of the whole fruit), causing unprecedented environmental burdens. Hesperidin, a flavonoid abundant in orange peels, is considered to hold immense potential for clean skin health product applications due to its antioxidant, anti-inflammatory, and anticarcinogenic properties. This review explores hesperidin extraction and purification methodologies as well as key skincare application areas: (i) antiaging and skin barrier enhancement, (ii) UV radiation-induced damage, (iii) hyperpigmentation and depigmentation conditions, (iv) wound healing, and (v) skin cancer and other cutaneous diseases. This work's novelty lies in the comprehensive coverage of hesperidin's promising skincare applications while also demonstrating its potential as a sustainable ingredient from a circular economy approach.

Antioxidant and anti-inflammatory activity through inhibition of NF-κB and sEH of some citrus peel and phytoconstituent characteristics

In Indonesia, there are many types of citrus where parts of the fruit, leaves, and peel can be utilized as food, drinks, spices, and medicine. This research aims to determine the phytochemical characteristics, antioxidant activities, and anti-inflammatory activity through inhibition of NF-κB and sEH, and the main phytoconstituents of three types of citrus fruits that are commonly used as herbs in Indonesia. The flesh and peel of Citrus amblycarpa/CAm, C. aurantiifolia/CAu, and C. hystrix/CH were extracted by Ultrasound-Assisted Extraction (UAE) with 70 % ethanol and then concentrated. All extracts were tested for total flavonoid content (TFC), total polyphenolic content (TPC), chemical constituents using LCMS, and DPPH radical scavenging activity. Molecular docking tests of 33 compounds containing CAm, CAu, and CH fruit peels from the literature study against NF-κB (Nuclear Factor Kappa Beta) and sEH (Soluble Epoxide Hydrolase) were also conducted. The TFC in fruit peels was 13.47-17.34 mg QE/g extract, and in flesh was 1.35-2.51 mg QE/g extract. The TPC in fruit peels was 4.28-6.3 mg GAE/g extract, and in flesh was 0.85-2.09 mg GAE/g extract. The IC50 values of antioxidant activity on fruit peel were 74.01-168.54 µg/mL; and flesh 185.62-2669 µg/mL. CAu peels provided the highest antioxidant activity and polyphenol content. The LC-MS/MS test on citrus peels shows the main chemical compounds: naringin (C27H32O14), naringenin (C15H12O5), hesperidin (C28H34O15), and hesperitin (C16H14O6). Molecular docking shows that naringin and neohesperidin predicted inhibit NF-κB, and hesperidin, neohesperidin, narirutin, naringin, apigenin, kaempferol, quercetin, rutin, eriocitrin, sinensetin, and vitamin A predicted can inhibit sEH enzyme. All citrus peel has stronger antioxidant activity and more flavonoids and phenolics than the flesh. Naringin and neohesperidin can inhibit NF-κB and sEH enzymes. The main flavonoid contents of the citrus peels and presumed to have activity are hesperidin and naringin. These flavonoids and their glycosides can be used as marker phytoconstituents in the quality assurance of pharmaceutical products.

Bioactive Compounds from Kinnow Processing Waste and their Associated Benefits: A Review

We have explored the expansive possibilities of kinnow peel, a frequently ignored by-product of the fruit processing industry, in this thorough analysis. The production of kinnow generates a significant amount of waste, including peel, seeds, and pulp. The disposal of this waste is a major environmental issue, as it can lead to pollution and greenhouse gas emissions. Due to the presence of bioactive substances that may be used in a variety of sectors, kinnow processing waste has the potential to provide a number of advantages. In the culinary, pharmaceutical, and cosmetic industries, the peel, seeds, and pulp from kinnow can be used as natural sources of antioxidants, aromatics, pectin, and dietary fibre. Utilizing kinnow waste promotes eco-innovation, increases sustainability, and aids in waste reduction. The development of a circular economy can be sped up with more study and commercialization of kinnow waste products. This analysis emphasises how important it is to understand and utilise the unrealized potential of agricultural byproducts, like kinnow peel.

Ultrasound-assisted extraction of polyphenols from pine needles (Pinus elliottii): Comprehensive insights from RSM optimization, antioxidant activity, UHPLC-Q-Exactive Orbitrap MS/MS analysis and kinetic model

Extracting polyphenolic bioactive compounds from Pinus elliottii needles, a forestry residue, promises economic and environmental benefits, however, relevant experimental data are lacking. Herein, a comprehensive investigation of the polyphenolic composition of pine needles (PNs) was carried out. Ultrasound-Assisted Extraction (UAE) was applied to extract the polyphenolic compounds of pine needles. The optimal conditions of extracts were determined by Response Surface Methodology (RSM). The maximum total phenolic content (TPC) of 40.37 mg GAE/g PNs was achieved with solid-liquid ratio of 1:20, 60 % ethanol, and 350 W for 25 min at 45 °C. Polyphenolic extracts showed antioxidant activity in scavenging free radicals and reducing power (DPPH, IC50 41.05 μg/mL; FRAP 1.09 mM Fe2+/g PNs; ABTS, IC50 214.07 μg/mL). Furthermore, the second-order kinetic model was also constructed to describe the mechanism of the UAE process, with the extraction activation energy estimated at 12.26 kJ/mol. In addition, 37 compounds in PNs were first identified by UHPLC-Q-Exactive Orbitrap MS/MS, including flavonoids and phenolic acids. The results suggest that Ultrasound-Assisted is an effective method for the extraction of natural polyphenolic compounds from pine needles and this study could serve as a foundation for utilizing phenolics derived from PNs in the food and pharmaceutical industries.

Citrus Peel Extracts: Effective Inhibitors of Heterocyclic Amines and Advanced Glycation End Products in Grilled Pork Meat Patties

In the present study, citrus peels were extracted using various conventional and deep eutectic solvents (DESs). Compared to other citrus peel extracts, the DES extract based on choline chloride showed notably higher total phenolic and flavonoid content levels, along with superior antioxidant activity, among these extracts. Consequently, this study aimed to further investigate the inhibitory effects of the choline chloride based DES extract on the production of both free and bound heterocyclic amines (HAs) and advanced glycation end products (AGEs) in roast pork meat patties. The results indicated that the addition of choline chloride-based DES extracts, particularly the choline chloride-carbamide based DES extract, can effectively reduce the oxidation of lipids and proteins by quenching free radicals. This approach proves to be the most efficient in reducing the formation of both HAs and AGEs, leading to a significant reduction of 19.1-68.3% and 11.5-66.5% in free and protein-bound HAs, respectively. Moreover, the levels of free and protein-bound AGEs were reduced by 50.8-50.8% and 30.5-39.8%, respectively, compared to the control group. Furthermore, the major phenolics of citrus peel extract identified by UHPLC-MS were polymethoxylated flavonoids (PMFs) including hesperidin, isosinensetin, sinensetin, tetramethoxyflavone, tangeretin, and hexamethoxyflavone, which inferring that these compounds may be the main active ingredients responsible for the antioxidant activity and inhibition effects on the formation of HAs and AGEs. Further research is needed to explore the inhibitory effects and mechanisms of PMFs with different chemical structures on the formation of HAs and AGEs.

Phenolic Compounds from By-Products for Functional Textiles

Textile dyeing is known to have major environmental concerns, especially with the high use of toxic chemicals. The use of alternatives such as natural dyes rich in phenolic compounds has become extremely appealing in order to move towards a more sustainable circular economy. Phenolic dyes have the potential to functionalize textile fabrics with properties such as antimicrobial, antioxidant, and UV protection. Wastes/residues from the agri-food industries stand out as highly attractive sources of these compounds, with several by-products showing promising results in textile dyeing through the implementation of more sustainable and eco-friendly processes. This review presents an up-to-date exploration of the sources of phenolic compounds used in the textile industry over the past two decades, with a primary focus on the functional properties they provide to different fabrics. The research highlights a surge in interest in this theme since 2017, accentuating a noticeable upward trend. Throughout this review, emphasis is given to by-products from the agri-food industry as the sources of these compounds. The reviewed papers lay the foundation for future research, paving the way for exploring the potential of raw materials and by-products in the creation of functional and smart textiles.

Effect of free and bound polyphenols from Rosa roxburghii Tratt distiller's grains on moderating fecal microbiota

Rosa roxburghii Tratt distiller's grains (R. roxburghii DGs), the main by-product of wine processing, showed functional value and potential for high-value usage which benefited from their rich polyphenols. In this study, the free and bound polyphenols from R. roxburghii DGs were extracted and their potential effect on modulating fecal microbiota was investigated using in vitro fecal fermentation. The free polyphenols (26.32-26.45 mg GAE/g) showed higher antioxidant activity compared to the bound polyphenols (8.76-9.01 mg GAE/g). The free and bound polyphenols significantly improved the fecal microbiota community structure and enhanced short chain fatty acids concentrations after the stimulated colonic fermentation for 24 h. Furthermore, the effect of R. roxburghii DGs polyphenols on modulating fecal microbiota was primarily attributed to quercetin, catechin, kaempferol, cyanidin and baicalin. This research suggests that R. roxburghii DGs are a promising source of natural antioxidants and prebiotic foods.

Valorization of Citrus reticulata Blanco Peels to Produce Enriched Wheat Bread: Phenolic Bioaccessibility and Antioxidant Potential

The fortification of foods with bioactive polyphenols aims to improve their functional properties and to provide health benefits. Yet, to exert their benefits, phenolic compounds must be released from the food matrix and absorbed by the small intestine after digestion, so assessing their bioaccessibility is crucial to determine their potential role. This work aims to incorporate Citrus reticulata Blanco peel extracts into wheat bread as a promising opportunity to increase their bioactive potential, along with supporting the sustainable management of citrus-industry waste. A control and a wheat bread enriched at 2% and 4% (w/v) with a phenolic extract from mandarin peels were prepared and analyzed for antioxidant activity and phenolic composition using LC-MS and UV-Vis spectrophotometry. In addition, in vitro digestion was performed, and the digested extracts were analyzed with HPLC-MS/MS. The results showed a significant increase in total flavonoid content (TFC, 2.2 ± 0.1 mg·g-1), antioxidant activity (IC50 = 37 ± 4 mg·g-1), and contents of quercetin, caffeic acid, and hesperidin in the 4% (w/v) enriched bread. Yet, most polyphenols were completely degraded after the in vitro digestion process, barring hesperidin (159 ± 36 μg·g-1), highlighting the contribution of citrus enrichment in the development of an enriched bread with antioxidant potential.

Optimization of QuEChERS Extraction for Determination of Carotenoids, Polyphenols, and Sterols in Orange Juice Using Design of Experiments and Response Surface Methodology

Several compounds with different physical properties are present in foods, biological components, and environmental samples, and there are cases in which these must be analyzed simultaneously. However, it is difficult to extract compounds with different physical properties from the same sample using a single method. In the present study, we examined the optimal conditions for the QuEChERS extraction of several kinds of compounds from orange juice using design of experiments (DoE) and response surface methodology (RSM) to determine the optimal ratio of organic solvent to sodium chloride. We determined the optimal extraction conditions, which were within the design space, using 100% tetrahydrofuran (THF) as the extraction organic solvent and NaCl:MgSO4 = 75:25 as the salt. The developed LC/MS/MS method using QuEChERS extraction achieved specific detection and precise quantification. Finally, we measured the polyphenols, sterols, and carotenoids in citrus juice using the optimized QuEChERS extraction method before LC/MS/MS analysis. Most of the analytes were quantifiable in orange juice. The optimized method achieved ease of operation, the extraction of analytes from food samples in a short time (within 30 min), minimization of analytical residues, and reliability. The DoE and RSM approach may contribute to better optimization of the extraction conditions for the lowest number of experiments.

Antioxidants from different citrus peels provide protection against cancer

Cancer is one of the leading causes of death. Despite significant advancements in the discovery of medications for the treatment of cancer, these drugs are hindered by applicability and efficacy issues and frequently exhibit major side effects that can further impair patients 'quality of life. Therefore, the development of therapeutically sound anti-cancer medicines derived from natural products has gained prominence in the field of functional foods. Some of these compounds have shown efficacy in the prevention and treatment of cancer as well as low toxicity. Additionally, many recent studies have explored the recycling of agro-industrial waste to create bioactive chemicals. Citrus peels are produced in vast quantities in the food processing sector; due to their abundance of flavonoids, they may be inexpensive sources of protection against several cancers. Citrus is a common type of fruit that contains a variety of nutrients. In particular, the antioxidant chemicals found in citrus peel have been identified as potential cancer-fighting agents. Antioxidant substances such as flavonoids prevent the development of cancer by inhibiting the metastatic cascade, decreasing the mobility of cancer cells in the circulatory system, promoting apoptosis, and suppressing angiogenesis. To explore the most effective uses of citrus peel-derived antioxidants, this review presents background information, an overview of the role of citrus antioxidants in cancer therapy, and a discussion of the key underlying molecular mechanisms.

Recent advances in bio-based extraction processes for the recovery of bound phenolics from agro-industrial by-products and their biological activity

Usually found bound to other complex molecules (e.g., lignin, hemicellulose), phenolic compounds (PC) are widely present in agro-industrial by-products, and their extraction is challenging. In recent times, research is starting to highlight the bioactive roles played by bound phenolics (BPC) in human health. This review aims at providing a critical update on recent advances in green techniques for the recovery of BPC, focusing on enzymatic-assisted (EAE) and fermentation-assisted extraction (FAE) as well as in the combination of technologies, showing variable yield and features. The present review also summarizes the most recent biological activities attributed to BPC extracts until now. The higher antioxidant activity of BPC-compared to FPC-coupled with their affordable by-product source make them medicinally potent and economically viable, promoting their integral upcycling and generating new revenue streams, business, and employment opportunities. In addition, EAE and FAE can have a biotransformative effect on the PC itself or its moiety, leading to improved extraction outcomes. Moreover, recent research on BPC extracts has reported promising anti-cancer and anti-diabetic activity. Yet further research is needed to elucidate their biological mechanisms and exploit the true potential of their applications in terms of new food products or ingredient development for human consumption.

Analytical quality-by-design (AQbD) approach for comprehensive analysis of bioactive compounds from Citrus peel wastes by UPLC

The growing interest in ingredients from natural sources has expanded the need for quality assessments of plant extracts. Analytical quality-by-design (AQbD) has been increasingly applied in regulated environments such as pharmaceutical industries and, more recently, for the bioactive compounds found in botanical materials. This work aimed to obtain qualitative (overall resolution and maximum peak capacity) and quantitative performances for target analytes using AQbD principles. The analytical target profile was elaborated; critical method parameters (independent variables) that affect the critical method attributes (dependent variables) were selected from a risk assessment for a reversed-phase liquid chromatography with diode array detection (RPLC-DAD) method. YMC-Triart C18 (3.0 × 100 mm, 1.9 μm) and a gradient elution using 0.2% acetic acid and methanol:acetonitrile 1:3 (v/v) were chosen as the stationary and mobile phases, respectively. The optimal and robust conditions (temperature at 33.3 °C, flow rate of 0.68 mL.min^-1, and a gradient slope of 4.18%.min^-1) were established by the method operable design region (MODR). The validation was performed by accuracy profiles using 90% expectation tolerance intervals for the selected compounds found in Citrus spp. using C. japonica as blank matrix. The lower limits of quantification for hesperidin, bergapten, herniarin, and citropten were 5.32, 0.40, 0.49, and 0.52 mg.L^-1, respectively (acceptance limit was set at ± 20%). Nobiletin did not show an adequate quantitative performance.

The Chemical Variability, Nutraceutical Value, and Food-Industry and Cosmetic Applications of Citrus Plants: A Critical Review

Citrus fruits occupy an important position in the context of the fruit trade, considering that both fresh fruits and processed products are produced on a large scale. Citrus fruits are recognized as an essential component of the human diet, thanks to their high content of beneficial nutrients such as vitamins, minerals, terpenes, flavonoids, coumarins and dietary fibers. Among these, a wide range of positive biological activities are attributed to terpenes and flavonoids derivatives. In this review, a list of bibliographic reports (from 2015 onwards) on the phytochemical composition, beneficial effects and potential applications of citrus fruits and their by-products is systematically summarized. In detail, information regarding the nutraceutical and medicinal value closely linked to the presence of numerous bioactive metabolites and their growing use in the food industry and food packaging, also considering any technological strategies such as encapsulation to guarantee their stability over time, were evaluated. In addition, since citrus fruit, as well as its by-products, are interesting alternatives for the reformulation of natural cosmetic products, the sector of the cosmetic industry is also explored. More in-depth knowledge of the latest information in this field will contribute to future conscious use of citrus fruits.

Citrus Waste as Source of Bioactive Compounds: Extraction and Utilization in Health and Food Industry

The current research was conducted to extract the bioactive compounds from citrus waste and assess their role in the development of functional foods to treat different disorders. The scientific name of citrus is Citrus L. and it belongs to the Rutaceae family. It is one of the most important fruit crops that is grown throughout the world. During processing, a large amount of waste is produced from citrus fruits in the form of peel, seeds, and pomace. Every year, the citrus processing industry creates a large amount of waste. The citrus waste is composed of highly bioactive substances and phytochemicals, including essential oils (EOs), ascorbic acid, sugars, carotenoids, flavonoids, dietary fiber, polyphenols, and a range of trace elements. These valuable compounds are used to develop functional foods, including baked products, beverages, meat products, and dairy products. Moreover, these functional foods play an important role in treating various disorders, including anti-aging, anti-mutagenic, antidiabetic, anti-carcinogenic, anti-allergenic, anti-oxidative, anti-inflammatory, neuroprotective, and cardiovascular-protective activity. EOs are complex and contain several naturally occurring bioactive compounds that are frequently used as the best substitutes in the food industry. Citrus essential oils have many uses in the packaging and food safety industries. They can also be used as an alternative preservative to extend the shelf lives of different food products.

Effect of Storage and Drying Treatments on Antioxidant Activity and Phenolic Composition of Lemon and Clementine Peel Extracts

Obtaining polyphenols from horticultural waste is an emerging trend that enables the valorization of resources and the recovery of value-added compounds. However, a pivotal point in the exploitation of these natural extracts is the assessment of their chemical stability. Hence, this study evaluates the effect of temperature storage (20 and -20 °C) and drying methods on the phenolic composition and antioxidant activity of clementine and lemon peel extracts, applying HPLC-DAD-MS, spectrophotometric methods, and chemometric tools. Vacuum-drying treatment at 60 °C proved to be rather suitable for retaining the highest antioxidant activity and the hesperidin, ferulic, and coumaric contents in clementine peel extracts. Lemon extracts showed an increase in phenolic acids after oven-drying at 40 °C, while hesperidin and rutin were sustained better at 60 °C. Hydroethanolic extracts stored for 90 days preserved antioxidant activity and showed an increase in the total phenolic and flavonoid contents in lemon peels, unlike in clementine peels. Additionally, more than 50% of the initial concentration was maintained up to 51 days, highlighting a half-life time of 71 days for hesperidin in lemon peels. Temperature was not significant in the preservation of the polyphenols evaluated, except for in rutin and gallic acid, thus, the extracts could be kept at 20 °C.

Valorization of Fruit Waste for Bioactive Compounds and Their Applications in the Food Industry

The fruit production and processing sectors produce tremendous amounts of by-products and waste that cause significant economic losses and an undesirable impact on the environment. The effective utilization of these fruit wastes can help to reduce the carbon footprint and greenhouse gas emissions, thereby achieving sustainable development goals. These by-products contain a variety of bioactive compounds, such as dietary fiber, flavonoids, phenolic compounds, antioxidants, polysaccharides, and several other health-promoting nutrients and phytochemicals. These bioactive compounds can be extracted and used as value-added products in different industrial applications. The bioactive components extracted can be used in developing nutraceutical products, functional foods, or food additives. This review provides a comprehensive review of the recent developments in fruit waste valorization techniques and their application in food industries. The various extraction techniques, including conventional and emerging methods, have been discussed. The antioxidant and antimicrobial activities of the active compounds extracted and isolated from fruit waste have been described. The most important food industrial application of bioactive compounds extracted from fruit waste (FW) has been provided. Finally, challenges, future direction, and concluding remarks on the topic are summarized.

Towards food circular economy: hydrothermal treatment of mixed vegetable and fruit wastes to obtain fermentable sugars and bioactive compounds

Due to processing activity, fruits and vegetables generate notable amounts of wastes at the processing, retail, and consumption level. Following the European goals for reducing food wastes and achieving a circular economy of resources, these biowastes should be valorized. In this work, hydrothermal hydrolysis at different conditions (temperatures, times, waste/water ratio, pH values) were tested to treat for first time; biowastes composed of mixed overripe fruits or vegetables to maximize the extraction of fermentable sugars that can be used as substrates in bioprocesses. Experimental data were fitted by a model based on irreversible first-order reactions, and kinetic constants were obtained. When hydrolysis of fruit wastes was carried out at 135 °C and pH 5 during 40 min, more than 40 g of reducing sugars per 100 g of waste (dry weight) could be obtained (represents an extraction of 97% of total carbohydrates). Concentrations of inhibitor compounds (HMF, furfural, acetic acid) in the hydrolysates were very low and, as example, a fermentation to obtain bioethanol was successfully carried out with an efficiency above 95%. Additionally, the production by hydrothermal treatment of bioactive compounds was investigated and the best results obtained were 92% DPPH inhibition and 12 mg GAE/g (dry weight) for antioxidant activity and phenolic compounds, respectively. These values are similar or even higher than those reported in literature using specific parts of fruits and vegetables.

Mediterranean Food Industry By-Products as a Novel Source of Phytochemicals with a Promising Role in Cancer Prevention

The Mediterranean diet is recognized as a sustainable dietary approach with beneficial health effects. This is highly relevant, although the production of typical Mediterranean food, i.e., olive oil or wine, processed tomatoes and pomegranate products, generates significant amounts of waste. Ideally, this waste should be disposed in an appropriate, eco-friendly way. A number of scientific papers were published recently showing that these by-products can be exploited as a valuable source of biologically active components with health benefits, including anticancer effects. In this review, accordingly, we elaborate on such phytochemicals recovered from the food waste generated during the processing of vegetables and fruits, typical of the Mediterranean diet, with a focus on substances with anticancer activity. The molecular mechanisms of these phytochemicals, which might be included in supporting treatment and prevention of various types of cancer, are presented. The use of bioactive components from food waste may improve the economic feasibility and sustainability of the food processing industry in the Mediterranean region and can provide a new strategy to approach prevention of cancer.

The recovery from agro-industrial wastes provides different profiles of anti-inflammatory polyphenols for tailored applications

Food and agro-industrial processing produce a great amount of side-stream and waste materials that are excellent sources of functional bioactive molecules such as phenolic compounds that recover them can be beneficial not only for food sustainability but also to human for many industrial applications such as flavor compounds and therapeutic applications such as antimicrobial and anti-inflammatory. The treatments and extraction techniques have major effects on the recovery of bioactive compounds. Along with the conventional extraction methods, numerous innovative techniques have been evolved and have been optimized to facilitate bioactive extraction more efficiently and sustainably. In this work, we have summarized the state-of-the-art technological approaches concerning novel extraction methods applied for five most produced crops in Italy; Grape Pomace (GP), Tomato Pomace (TP), Olive Pomace (OP), Citrus Pomace (CP), and Spent Coffee Grounds (SCG), presenting the extraction yield and the main class of phenolic classes, with the focus on their biological activity as an anti-inflammatory in vitro and in vivo studies via describing their molecular mechanism of action.