Valorization of citrus peel waste for the sustainable production of value-added products

The Role of Antioxidant Compounds from Citrus Waste in Modulating Neuroinflammation: A Sustainable Solution

In normal conditions, neuroinflammation induces microglia and astrocyte activation to maintain brain homeostasis. However, excessive or prolonged neuroinflammation can inflict harmful damage on brain tissue. Numerous factors can trigger chronic neuroinflammation, ultimately leading to neurodegeneration. In this context, considering the pressing need for novel, natural approaches to mitigate neuroinflammatory damage, attention has turned to unconventional sources such as agricultural by-products. Citrus fruits are widely consumed globally, producing substantial waste, including peels, seeds, and pulp. Traditionally regarded as agricultural waste, these by-products are now recognized as valuable reservoirs of bioactive compounds, including flavonoids, carotenoids, terpenoids, and limonoids. Among these, citrus polyphenols-particularly flavanones like hesperidin, naringenin, and eriocitrin-have emerged as potent modulators of neuroinflammatory pathways through their multifaceted interactions with cellular antioxidant systems, pro-inflammatory signaling cascades, neurovascular integrity, and gut-brain axis dynamics. This review aims to characterize the key molecules present in citrus waste and synthesizes preclinical and clinical evidence to elucidate the biochemical mechanisms underlying neuroinflammation in neurodegenerative disorders.

Valorization of Citrus Peel Byproducts: A Sustainable Approach to Nutrient-Rich Jam Production

The valorization of citrus peel byproducts presents a sustainable and innovative approach to reducing food waste while improving the nutritional content of fruit-based products. Citrus peels, a significant byproduct of the fruit juice industry, are abundant in bioactive compounds with recognized health benefits and functional properties, making them particularly suitable for jam production. The global citrus industry generates substantial amounts of waste, with peels accounting for approximately 50% of the total fruit mass. Conventional disposal methods often result in environmental concerns and the underutilization of valuable bioresources. This study aims to investigate the potential of incorporating citrus peel into jam formulations as a means of enhancing their nutritional and functional properties. Jams were prepared using a traditional processing technique (TP) incorporating citrus peel. The experimental jam variants included pomelo peel jam (PPJ), lime peel jam (LiPJ), lemon peel jam (LePJ), clementine peel jam (CPJ), orange peel jam (OPJ), and grapefruit peel jam (GPJ). All jam samples were subjected to comprehensive analyses, including assessments of chemical composition, total soluble solids (TSSs), titrable acidity (g/100 g acid citric), macro- and microelement contents, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity using the FRAP assay. The study revealed high levels of biologically active compounds, such aspolyphenols, flavonoids, and vitamin C, in the jams, highlighting their antioxidant properties and potential health benefits. Among the jams, lemon peel jam (LePJ) exhibited the highest antioxidant activity and polyphenol content, making it a superior choice in terms of functional benefits. In terms of sensory analysis, orange peel jam (OPJ) was the most favored by consumers, demonstrating its high acceptability and potential for market success.

Microbial conversion of Limonene-containing waste into transesterifiable bio-lipids: Evaluating oleaginous bacterial isolates

Bio-oil is increasingly recognized as a sustainable and eco-friendly energy source, offering a viable alternative to petro-diesel. This study evaluates the bio-oil production potential of a novel oleaginous strain, KM9 (Serratia surfactantfaciens YD25) compared with the known oleaginous species R. erythropolis. Growth conditions and nutrient requirements were optimized for both strains to maximize biomass production and lipid accumulation. Utilizing orange waste as a substrate not only contributes to waste minimization but also provides a renewable carbon source for microbial lipid synthesis. KM9 demonstrated exceptional performance, achieving 50% reduction in organic matter from the orange waste while simultaneously accumulating lipids upto 38% of its dry cell weight. Gas chromatography-mass spectrometry (GC-MS) analysis of the transesterified lipids revealed that both KM9 and R. erythropoliss produced comparable levels of saturated fatty acids (38.39% and 39%, respectively), when cultivated in limonene-modified media. Notably, the use of orange waste stimulated the production of monounsaturated fatty acids (MUFAs), particularly palmitic and stearic acids, resulting in a lipid profile closely resembling that of plant-based bio-oils. These findings highlight the promising potential of the oleaginous strain KM9 for producing microbial lipids from orange waste, contributing to sustainable biodiesel production and effectively valorizing a significant agricultural waste stream.

Sustainable strategies to obtain bioactive compounds from citrus peels by supercritical fluid extraction, ultrasound-assisted extraction, and natural deep eutectic solvents

This work proposes a sustainable sequential extraction of bioactive terpenoids and phenolic compounds from grapefruit, lime, and lemon peels using supercritical CO2 extraction (SC-CO2) and ultrasound-assisted extraction (UAE) with natural deep eutectic solvents (NaDES). NaDES screening demonstrated that Choline Chloride:Tartaric acid (1:2) for grapefruit and lemon peels, and Choline Chloride:Glycerol (1:2) for lime peels with 50% water yielded the highest phenolic contents. Cryogenic grinding (CR) and SC-CO2 pretreatments before UAE-NaDES did not improve phenolic recovery compared to direct UAE-NaDES. Pretreatments reduced particle size and increased surface tension, lowering UAE-NaDES efficiency. The direct UAE-NaDES extracts showed the highest phenolic diversity, with naringin in grapefruit and hesperidin in lime and lemon peels as the major compounds identified by HPLC-QTOF-MS. However, SC-CO2 obtained before UAE-NaDES presented higher anticholinergic capacity and a rich terpenoid profile identified by GC-Q-MS. Results demonstrate the potential of this sequential strategy for a more holistic exploitation of citrus peels.

A Comprehensive Analysis of Non-Thermal Ultrasonic-Assisted Extraction of Bioactive Compounds from Citrus Peel Waste Through a One-Factor-at-a-Time Approach

Food waste presents a critical environmental and economic challenge across Europe. In the Mediterranean region, the agricultural industry generates considerable quantities of citrus fruits, leading to significant byproduct waste, which remains underutilized. To help address this, this study explored the valorization of orange peel waste using non-thermal ultrasonic-assisted extraction (UAE) and a one-factor-at-a-time experimental design to investigate the effects of nine chemical and physical UAE parameters. The goal was to identify ideal operational ranges for each parameter using several responses (bioactive compound recovery, antioxidant activity, and radical scavenging activity), thus elucidating the most influential UAE factors and their role in co-extracting various classes of natural compounds. The key findings revealed that the polarity and ionic potential of the extraction medium, tuned through ethanol:water or pH, significantly influenced both the chemical profile and bioactivity of the extracts. Notably, citric acid and citrates appeared to stabilize co-extracted compounds. Lower solid-to-liquid ratios increased yields, while particle sizes between 1400 and 710 µm enhanced phenolic recovery by approximately 150 mg/L GAE. In contrast, increases in pulse, probe diameter, immersion depth, and extraction time led to degradation of bioactive compounds, whereas the maximal amplitude improved phenolic acid recovery by up to 2-fold. Collectively, these insights provide a foundation for optimizing non-thermal UAE to valorize orange peel waste.

Exploring the competitive inhibition of α-glucosidase by citrus pectin enzymatic hydrolysate and its mechanism: An integrated experimental and simulation approach

The endo-polygalacturonase D (PgaD) from Aspergillus niger JL15 was recombinantly expressed in Escherichia coli BL21, exhibiting an optimal activity at 55 °C and pH 4.0. Hydrolysis products of citrus pectin by recombinant PgaD included galacturonic acid (GalA), digalacturonic acid (GalA2), trigalacturonic acid (GalA3), and tetragalacturonic acid (GalA4). The hydrolysates exhibited significant antioxidant capacity and dose-dependent competitive inhibition of α-glucosidase. GalA2 and GalA3 acted as competitive inhibitors of α-glucosidase, with inhibition constant of 0.0589 mmol.L-1 and 0.6732 mmol.L-1, respectively. Molecular dynamics (MD) simulations revealed that both GalA2 and GalA3 penetrated the catalytic pocket of α-glucosidase and formed stable hydrogen bonds with key catalytic residues D352 and D215. The binding free energies of GalA2-α-glucosidase and GalA3-α-glucosidase complexes were - 10.3 ± 0.6 kcal·mol-1 and -10.8 ± 0.7 kcal·mol-1, respectively. These findings might offer new ideas for the development of α-glucosidase inhibitors sourced from citrus pectin, as well as enhance utilization of the renewable plant polysaccharide resources.

A critical review of persimmon-derived pectin: Innovations in extraction, structural characterization, biological potentials, and health-promoting effects

Persimmon-derived pectin (PP) is a versatile dietary polysaccharide with considerable industrial and biological significance, demonstrating a range of functionalities and health-promoting benefits. This review explores the changes in PP during postharvest and processing, detailing structural alterations and extraction techniques for optimal characteristics. Key functional attributes of PP-such as emulsification, rheology, antioxidant capacity, immunomodulation, and gut microbiota regulation-highlight its potential applications in food, healthcare, pharmaceuticals, and cosmetics. The review also explores methods to enhance the functional properties of PP through synergistic interactions with polyphenols. A strategic roadmap for advancing PP research is proposed, connecting extraction methods, structural characteristics, and functional properties to tailor PP for specific applications in food science and technology. Overall, persimmon-derived pectin is positioned as a valuable food-derived bioactive ingredient with diverse capabilities, poised to drive innovation and advance nutritional science across multiple sectors.

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.

Valorizing Lycii fructus waste residue into polysaccharide-rich extracts: Extraction methodologies, physicochemical characterization, in vitro activities and economic feasibility

The high polysaccharide content of Lycii fructus agri-food waste should be reclaimed for value liberation from both environmental and economic perspectives. In this study, waste from L. fructus pigment products was valorized on a bench scale by upcycling into active polysaccharide-rich extracts. The methodological feasibility of polysaccharide recovery from L. fructus waste was evaluated using sequential extraction techniques. Three fractions LFP-30, LFP-100, and LFP-121, were obtained under stepwise increases in temperature and pressure. Highly heterogeneous xyloglucan (XG)-pectin macromolecules composed of linear homogalacturonan (HG) and alternating intra-RG-I-linkers, with topological neutral branches and XG participation, were predominant among the L. fructus polysaccharides (LFPs). Antioxidant activities in LFPs were unaffected by waste resources and severe extraction methodology conditions. Additionally, the direct investment potential of polysaccharide recovery was evaluated for full-scale implementation. This study demonstrated the necessity and feasibility of extracting bioactive polysaccharides with potential applications from L. fructus waste, and provided a sustainable strategy for transforming L. fructus waste disposal problems into value-added products using cost-effective methodologies.

Research advances in citrus polyphenols: green extraction technologies, gut homeostasis regulation, and nano-targeted delivery system application

Citrus polyphenols can modulate gut microbiota and such bi-directional interaction that can yield metabolites such as short-chain fatty acids (SCFAs) to aid in gut homeostasis. Such interaction provides citrus polyphenols with powerful prebiotic potential, contributing to guts' health status and metabolic regulation. Citrus polyphenols encompass unique polymethoxy flavonoids imparting non-polar nature that improve their bioactivities and ability to penetrate the blood-brain barrier. Green extraction technology targeting recovery of these polyphenols has received increasing attention due to its advantages of high extraction yield, short extraction time, low solvent consumption, and environmental friendliness. However, the low bioavailability of citrus polyphenols limits their applications in extraction from citrus by-products. Meanwhile, nano-encapsulation technology may serve as a promising approach to improve citrus polyphenols' bioavailability. As citrus polyphenols encompass multiple hydroxyl groups, they are potential to interact with bio-macromolecules such as proteins and polysaccharides in nano-encapsulated systems that can improve their bioavailability. This multifaceted review provides a research basis for the green and efficient extraction techniques of citrus polyphenols, as well as integrated mechanisms for its anti-inflammation, alleviating metabolic syndrome, and regulating gut homeostasis, which is more capitalized upon using nano-delivery systems as discussed in that review to maximize their health and food applications.

Reutilization of Fruit Waste as Potential Prebiotic for Probiotic or Food-grade Microorganisms in Food Applications: A Review

Food waste has been a global issue with 2.5 billion tons generated globally in 2021. Approximately 46% of the food waste is contributed by fruit and vegetable waste. Due to improper waste handling, these fruit by-products have a negative impact on the environment through soil and water pollution, the greenhouse effect, global warming, and eutrophication. However, research has shown the potential to reuse fruit waste in various applications for sustainability owing to their high source of valuable components and potential health benefits. In recent years, researchers have also explored the potential of reutilizing fruit waste as a prebiotic. Hence, literatures from the past 10 years has been critically analyzed and presented in this review. This review focused on the potential of fruit waste as a prebiotic for probiotic and gastrointestinal microorganisms and its food applications. The nutritional composition and bioactive compounds of the fruit wastes had been introduced to reflect their potential as prebiotics. Moreover, the increase in bioactive compounds and bioactivities in probiotics with the presence of fruit wastes has been reviewed. The impact of fruit by-products on the growth of the probiotic and its survivability in food matrices as compared to established prebiotic and the absence of prebiotics have also been extensively discussed in this review. This review also highlighted some of the factors that might contribute to the negative effect of fruit waste on probiotics. The safety concerns and future prospects of reutilizing fruit wastes for food applications have been emphasized. The review article is beneficial for researchers exploring fruit wastes as prebiotics and industrialists who are interested in incorporating fruit wastes as an added-value ingredient for food applications.

Citrus wastewater as a source of value-added products: Quali-quantitative analysis and in vitro screening on breast cancer cell lines

Citrus wastewater from industries is a source of bioactive compounds whose recovery could be a useful approach to convert processing waste into potential resources to be exploited in food, pharmaceutical, and chemical companies. Citrus wastewater, obtained from the industrial processing of Citrus sinensis, was freeze-dried and qualitative/quantitative evaluated using HPLC/MS Q-TOF analysis. Antiproliferative activity was investigated on MDA-MB-231 (triple-negative breast cancer cell line), MCF-7 (breast cancer cell line), and its multidrug-resistant variant MCF-7R. Fraction 8 emerged for its cytotoxicity toward MCF-7R cells. Its main component, the polymethoxylated flavone nobiletin (80%), is likely involved in increasing the number of G1-phase MCF-7R cells without inducing cell death. Notably, fraction 8 sensitizes MCF7-R cells to the antiproliferative effects of doxorubicin, thus contributing to overcoming MCF7-R multidrug resistance. Our studies highlighted the possibility of applying a sustainable strategy for citrus wastewater recycling to recover functional compounds as useful adjuvants for the prevention and treatment of malignancies.

The protective effect of hydroalcoholic Citrus aurantifolia peel extract against doxorubicin-induced nephrotoxicity

Background and purpose

Doxorubicin chemotherapy is a widely used treatment for various cancers, including breast, ovarian, and uterine cancers, among others. However, long-term use can cause nephrotoxicity side effects. Some citrus flavonoids have demonstrated nephroprotective activity; therefore, this study aimed to test the nephroprotective effectiveness of Citrus aurantifolia peel extract in protecting and reducing kidney damage caused by doxorubicin.

Experimental approach

Citrus aurantifolia peel was dried, ground, and extracted by ultrasonication (70% ethanol), then the extract was dried. Twenty-five female Sprague-Dawley rats were divided into 5 groups including the normal group (control), positive control (doxorubicin) group receiving doxorubicin at the repeated intraperitoneal (i.p.) dose of 4 mg/kg/day on days 2, 6, 10, and 14, and treatment groups receiving Citrus aurantifolia peel extract (CPE) with the doses of 100, 200, and 400 mg/kg/day orally for 14 days, and doxorubicin (4 mg/kg/day, i.p.) on days 2, 6, 10 and 14. On day 15, the rats were euthanized for the measurements of MDA, superoxide dismutase (SOD), catalase, kidney function (measuring blood urea nitrogen (BUN), creatinine, albumin serum levels), and renal histopathology.

Findings/Results

The CPE yield was 16.13%. CPE could significantly reduce the levels of MDA, and increase SOD and catalase activities compared with the doxorubicin-induced nephrotoxic model. CPE could increase renal function by reducing BUN and creatinine levels, increasing albumin, and improving the histopathology of the kidney.

Conclusion and implications

CPE has a potential effect as nephroprotective against doxorubicin-induced toxicity in renal through antioxidant capacities and increased renal function.

Circular Bioeconomy in Action: Transforming Food Wastes into Renewable Food Resources

The growing challenge of food waste management presents a critical opportunity for advancing the circular bioeconomy, aiming to transform waste into valuable resources. This paper explores innovative strategies for converting food wastes into renewable food resources, emphasizing the integration of sustainable technologies and zero-waste principles. The main objective is to demonstrate how these approaches can contribute to a more sustainable food system by reducing environmental impacts and enhancing resource efficiency. Novel contributions of this study include the development of bioproducts from various food waste streams, highlighting the potential of underutilized resources like bread and jackfruit waste. Through case studies and experimental findings, the paper illustrates the successful application of green techniques, such as microbial fermentation and bioprocessing, in valorizing food wastes. The implications of this research extend to policy frameworks, encouraging the adoption of circular bioeconomy models that not only address waste management challenges but also foster economic growth and sustainability. These findings underscore the potential for food waste to serve as a cornerstone in the transition to a circular, regenerative economy.

Unlocking the Potential of Food Waste: A Review of Multifunctional Pectins

This review comprehensively explores the multifunctional applications of pectins derived from food waste and by-products, emphasizing their role as versatile biomaterials in the medical-related sectors. Pectins, known for their polyelectrolytic nature and ability to form hydrogels, influence the chemical composition, sensory properties, and overall acceptability of food and pharmaceutical products. The study presents an in-depth analysis of molecular parameters and structural features of pectins, such as the degree of esterification (DE), monosaccharide composition, galacturonic acid (GalA) content, and relative amounts of homogalacturonan (HG) and rhamnogalacturonan I (RG-I), which are critical for their technofunctional properties and biological activity. Emphasis is placed on pectins obtained from various waste sources, including fruits, vegetables, herbs, and nuts. The review also highlights the importance of structure-function relationships, especially with respect to the interfacial properties and rheological behavior of pectin solutions and gels. Biological applications, including antioxidant, immunomodulatory, anticancer, and antimicrobial activities, are also discussed, positioning pectins as promising biomaterials for various functional and therapeutic applications. Recalled pectins can also support the growth of probiotic bacteria, thus increasing the health benefits of the final product. This detailed review highlights the potential of using pectins from food waste to develop advanced and sustainable biopolymer-based products.

Nutritional, Bioactive, and Health Potential of Pomelo (Citrus maxima): An Exotic Underutilized Fruit

Pomelo scientifically known as Citrus maxima belongs to the family Rutaceae and is one of the largest fruits among citrus varieties. Mainly pomelo comes in different flesh colors such as red, pink, light pink, and white. The principal pomelo fruit polyphenols are phenolic acids, flavonoids, anthocyanins, and tannins. Pomelo fruit generates a large number of wastes including peel, pomace, and seeds which are comprised of bioactive compounds. The bioactive compounds carried in waste improve health functionalities. The hesperidin, narirutin, naringin, and their aglycone (naringenin), which have traditionally been acknowledged to constitute a characteristic component of pomelo, are the fruit's major constituents. Also, pomelo fruit juice is high in vitamins A and C, and the peel offers high protein, carbohydrate, and mineral content. Pomelo production and processing of different byproducts have become a perfect and long-lasting resource for agriculture and the food industry. The wastes loaded with immense essential components in pomelo have great importance in terms of human health. To have unique goods, to increase high consumer acceptability, and to have health advantages, this work gives a summary of recent advancements made to date with nutritional benefits, bioactive elements, and health benefits of pomelo fruit.

Investigation of pectin deficiency in modulating the bioflavonoid profile of orange processing waste: A sustainable valorization of industrial waste

Orange processing waste (OPW) generated by the processing of oranges, as well as other citrus fruits, is a major source of pectin in the market nowadays. The residues generated during the pectin extraction process may contain many phytochemicals, including flavonoids. We use state-of-the-art techniques such as liquid chromatography high-resolution mass spectrometry (LC-HRMS/MS) and feature-based molecular network (FBMN) to annotate the flavonoids in OPWs. In particular, four flavonoids, hesperidin, naringin, diosmin, and hesperetin were quantified in the samples by LC-TDQ-MS. In total, 32 flavonoids from different classes were annotated, of which 16 were polymethoxylated flavonoids, 13 were flavonoid glycosides and 3 were flavanone aglycones. The results showed that flavonoid glycosides remain in high concentrations in OPWs from pectin factories even after pectin extraction by harsh conditions. The results show an exciting opportunity to harness the untapped potential of pectin factory waste as a renewable source for the extraction of glycoside flavonoids.

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.

Physicochemical and antioxidant properties of pectin from Actinidia arguta Sieb.et Zucc (A. arguta) extracted by ultrasonic

Pectin was extracted from Actinidia arguta Sieb. et Zucc (A.arguta) using the ultrasound-assisted acid method and the single acid method. The physicochemical properties, structure, and antioxidant properties of two different pectins were investigated. The results showed that the extraction yield of the ultrasound-assisted acid method is higher than that of the single acid method. The molecular structure of A. arguta pectin extracted by the ultrasound-assisted acid method belongs to a mixed structure of RG-I and HG-type domains. Through structural feature analysis, the ultrasound-assisted extraction pectin (UAP) has a more branched structure than the single acid-extracted pectin (SAP). The SAP has a higher degree of esterification than the UAP. The physical property results show that the viscosity, solubility, and water-holding capacity of the UAP are better than those of the SAP. The antioxidant test results show that the hydroxyl radical scavenging and reducing powers of the UAP are superior to those of the SAP. This study shows the composition, physicochemical properties, and antioxidant activity of A. arguta pectin extracted by the ultrasonic-assisted extraction method to provide a theoretical basis for its application as an antioxidant and other food additives in the food industry.

Laboratory evaluation of a bio-insecticide candidate from tangerine peel extracts against Trialeurodes vaporariorum (Homoptera: Aleyrodidae)

Background

The excessive use of synthetic insecticides in modern agriculture has led to environmental contamination and the development of insect resistance. Also, the prolonged use of chemical insecticides in producing flowers and tomatoes in greenhouses has caused health problems for workers and their offspring. In this study, we analyzed the efficacy of mandarin peel (Citrus reticulata L.) essential oil (EO) as a natural insecticide against greenhouse whitefly (Trieurodes vaporariorum W., Homoptera: Aleyrodidae), a common pest in greenhouse production of different crops.

Methods

Petroleum ether (PET) and n-hexane (HEX) were used as solvents to extract essential oil (EO) from tangerine peels.

Results

The yield of EO was 1.59% and 2.00% (m/m) for PET and HEX, respectively. Additionally, the insect-killing power of EO was tested by checking how many greenhouse whiteflies died at different times. The results showed that PET and HEX extracts of tangerine EO effectively controlled greenhouse whiteflies. Furthermore, with both solvents, a 12.5% (v/v) application was as practical as the commercial insecticide imidacloprid. Further characterization tests with the polarimeter, FTIR, HPLC-RP, and GC-MS showed that the essential oil (EO) contained about 41% (v/v) of d-limonene and that this compound may be responsible for the observed insecticidal properties.

Conclusion

Therefore, tangerine peel essential oil is an excellent botanical insecticide candidate for controlling greenhouse whiteflies.

Production of mannooligosaccharides from orange peel waste with β-mannanase expressed in Trichosporonoides oedocephalis

A large quantity of orange peel waste (OPW) is generated per year, yet effective biorefinery methods are lacking. In this study, Trichosporonoides oedocephalis ATCC 16958 was employed for hydrolyzing OPW to produce soluble sugars. Glycosyl hydrolases from Paenibacillussp.LLZ1 which can hydrolyze cellulose and hemicellulose were mined and characterized, with the highest β-mannanase activity of 39.1 U/mg at pH 6.0 and 50 ℃. The enzyme was overexpressed in T. oedocephalis and the sugar production was enhanced by 16 %. The accumulated sugar contains 57 % value-added mannooligosaccharides by the hydrolysis of mannans. The process was intensified by a pretreatment combining H2O2 submergence and steam explosion to remove potential inhibitors. The mannooligosaccharides yield of 6.5 g/L was achieved in flask conversion and increased to 9.7 g/L in a 5-L fermenter. This study improved the effectiveness of orange peel waste processing, and provided a hydrolysis-based methodology for the utilization of fruit wastes.

Sustainable management of tea wastes: resource recovery and conversion techniques

As the demand for tea (Camellia sinensis) has grown across the world, the amount of biomass waste that has been produced during the harvesting process has also increased. Tea consumption was estimated at about 6.3 million tonnes in 2020 and is anticipated to reach 7.4 million tonnes by 2025. The generation of tea waste (TW) after use has also increased concurrently with rising tea consumption. TW includes clipped stems, wasted tea leaves, and buds. Many TW-derived products have proven benefits in various applications, including energy generation, energy storage, wastewater treatment, and pharmaceuticals. TW is widely used in environmental and energy-related applications. Energy recovery from low- and medium-calorific value fuels may be accomplished in a highly efficient manner using pyrolysis, anaerobic digestion, and gasification. TW-made biochar and activated carbon are also promising adsorbents for use in environmental applications. Another area where TW shows promise is in the synthesis of phytochemicals. This review offers an overview of the conversion procedures for TW into value-added products. Further, the improvements in their applications for energy generation, energy storage, removal of different contaminants, and extraction of phytochemicals have been reviewed. A comprehensive assessment of the sustainable use of TWs as environmentally acceptable renewable resources is compiled in this review.

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.

Formulation of Antioxidant Gummies Based on Gelatin Enriched with Citrus Fruit Peels Extract

In this work, the peels of red and blonde oranges as well as lemons were efficiently (5.75-9.65% yield) extracted by hydroalcoholic solution with ultrasound assistance and employed as active molecule sources in the preparation of functional gummies. Antioxidant performances of the hydroalcoholic extracts were characterized by colorimetric assays, whereas LC-HRMS analyses identified the main bioactive compounds (phenolic acids and flavonoids). The highest scavenging activity was recorded for lemon extract in an aqueous environment (IC50 = 0.081 mg mL-1). An ecofriendly grafting procedure was performed to anchor polyphenols to gelatin chains, providing macromolecular systems characterized by thermal analysis and antioxidant properties. Scavenger abilities (IC50 = 0.201-0.454 mg mL-1) allowed the employment of the conjugates as functional ingredients in the preparation of gummies with remarkable antioxidant and rheological properties over time (14 days). These findings confirmed the possible employment of highly polluting wastes as valuable sources of bioactive compounds for functional gummies preparation.

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.

Response surface methodology-optimized extraction of flavonoids from pomelo peels and isolation of naringin with antioxidant activities by Sephadex LH20 gel chromatography

In this study, flavonoids were extracted from pomelo peels and naringin was isolated from the flavonoid extract. The effects of extraction parameters, namely, ethanol concentration, solid-to-liquid ratio, and extraction time, on the yield of flavonoids extracted from pomelo peels were analyzed according to the Box-Behnken design of response surface methodology. The experimental conditions for flavonoid extraction were optimized, and naringin was separated from the extracted flavonoids using Sephadex LH-20 column chromatography. Experimental results showed that the influence of factors on the extraction rate of flavonoids from pomelo peels was in the order of ethanol concentration > solid-to-liquid ratio > extraction time, and the optimal extraction parameters were 85% ethanol concentration, 1:20 solid-to-liquid ratio, and 4-h extraction time for extracting flavonoids from pomelo peels. Under these conditions, the yield of flavonoids was 6.07 ± 0.06 mg/g. After three times of extraction, the flavonoid extraction rate reached 96.55%, and the residual naringin in the pomelo peels was 0.017 mg/g, at which point the bitterness in the pomelo peels disappeared. Two components, namely, PF1 and PF2, were separated from the crude flavonoid of pomelo peels through Sephadex LH20 column chromatography. PF2 was identified as naringin by high-performance liquid chromatography tandem mass spectrometry, with a purity of 95.7 ± 0.23%. Both flavonoids and PF2 exhibited good in vitro radicals scavenging activities on DPPH, ABTS, superoxide anion and hydroxyl.

Towards Valorization of Food-Waste-Derived Pectin: Recent Advances on Their Characterization and Application

Pectin, a natural biopolymer, can be extracted from food waste biomass, adding value to raw materials. Currently, commercial pectin is mostly extracted from citrus peels (85.5%) and apple pomace (14.0%), with a small segment from sugar beet pulp (0.5%). However, driven by high market demand (expected to reach 2.12 billion by 2030), alternative agro-industrial waste is gaining attention as potential pectin sources. This review summarizes the recent advances in characterizing pectin from both conventional and emerging food waste sources. The focus is the chemical properties that affect their applications, such as the degree of esterification, the neutral sugars' composition, the molecular weight, the galacturonic acid content, and technological-functional properties. The review also highlights recent updates in nutraceutical and food applications, considering the potential use of pectin as an encapsulating agent for intestinal targeting, a sustainable biopolymer for food packaging, and a functional and emulsifying agent in low-calorie products. It is clear from the considered literature that further studies are needed concerning the complexity of the pectin structure extracted from emerging food waste raw materials, in order to elucidate their most suitable commercial application.

Citrus By-Products as a Valuable Source of Biologically Active Compounds with Promising Pharmaceutical, Biological and Biomedical Potential

Citrus fruits processing results in the generation of huge amounts of citrus by-products, mainly peels, pulp, membranes, and seeds. Although they represent a major concern from both economical and environmental aspects, it is very important to emphasize that these by-products contain a rich source of value-added bioactive compounds with a wide spectrum of applications in the food, cosmetic, and pharmaceutical industries. The primary aim of this review is to highlight the great potential of isolated phytochemicals and extracts of individual citrus by-products with bioactive properties (e.g., antitumor, antimicrobial, antiviral, antidiabetic, antioxidant, and other beneficial activities with health-promoting abilities) and their potential in pharmaceutical, biomedical, and biological applications. This review on citrus by-products contains the following parts: structural and chemical characteristics; the utilization of citrus by-products; bioactivities of the present waxes and carotenoids, essential oils, pectins, and phenolic compounds; and citrus by-product formulations with enhanced biocactivities. A summary of the recent developments in applying citrus by-products for the treatment of different diseases and the protection of human health is also provided, emphasizing innovative methods for bioaccessibility enhancements (e.g., extract/component encapsulation, synthesis of biomass-derived nanoparticles, nanocarriers, or biofilm preparation). Based on the representative phytochemical groups, an evaluation of the recent studies of the past six years (from 2018 to 2023) reporting specific biological and health-promoting activities of citrus-based by-products is also provided. Finally, this review discusses advanced and modern approaches in pharmaceutical/biological formulations and drug delivery (e.g., carbon precursors for the preparation of nanoparticles with promising antimicrobial activity, the production of fluorescent nanoparticles with potential application as antitumor agents, and in cellular imaging). The recent studies implementing nanotechnology in food science and biotechnology could bring about new insights into providing innovative solutions for new pharmaceutical and medical discoveries.

Transcriptome and UPLC-MS/MS reveal mechanisms of amino acid biosynthesis in sweet orange 'Newhall' after different rootstocks grafting

Sweet orange 'Newhall' (C. sinensis) is a popular fruit in high demand all over the world. Its peel and pulp are rich in a variety of nutrients and are widely used in catering, medicine, food and other industries. Grafting is commonly practiced in citrus production. Different rootstock types directly affect the fruit quality and nutritional flavor of citrus. However, the studies on citrus metabolites by grafting with different rootstocks are very limited, especially for amino acids (AAs). The preliminary test showed that there were significant differences in total amino acid content of two rootstocks (Poncirus trifoliata (CT) and C. junos Siebold ex Tanaka (CJ)) after grafting, and total amino acid content in the peel was higher than flesh. However, the molecular mechanism affecting amino acid differential accumulation remains unclear. Therefore, this study selected peel as the experimental material to reveal the amino acid components and differential accumulation mechanism of sweet orange 'Newhall' grafted with different rootstocks through combined transcriptome and metabolome analysis. Metabolome analysis identified 110 amino acids (AAs) and their derivatives in sweet orange 'Newhall' peels, with L-valine being the most abundant. L-asparagine was observed to be affected by both developmental periods and rootstock grafting. Weighted gene co-expression network analysis (WGCNA) combined with Redundancy Analysis (RDA) revealed eight hub structural genes and 41 transcription factors (TFs) that significantly influenced amino acid biosynthesis in sweet orange 'Newhall' peels. Our findings further highlight the significance of rootstock selection in enhancing the nutritional value of citrus fruits and might contribute to the development of functional citrus foods and nutritional amino acid supplements.

Microwave-assisted valorization and characterization of Citrus limetta peel waste into pectin as a perspective food additive

Machine learning techniques were employed to evaluate the effect of process parameters viz. microwave power (100 W, 300 W, 600 W); pH (1, 1.5, 2); and microwave time (the 60 s, 120 s, 180 s) on the pectin yield from Citrus limetta peel. A fourth-order polynomial function of 66.60 scales was used by the Support Vector Regression (SVR) model at an epsilon (ε) value of 0.003. The co-efficient of determination (R2) and root mean square error-values for training data and test data were 0.984; 0.77 and 0.993; 0.66 respectively. At optimized conditions, microwave power 600 W, pH 1, and time 180 s the best yield of 32.75% was obtained. The integrity of pectin skeletal was confirmed with FTIR and 1H NMR spectrums. The physicochemical analysis revealed that CLP is a high-methoxyl pectin (HMP) with a 63.20 ± 0.88% degree of esterification, 798.45 ± 26.15 equivalent weight, 8.06 ± 0.62% methoxyl content, 67.93 ± 3.36 AUA content, 6.27 ± 0.27 g water/g pectin WHC, 2.68 ± 0.20 g oil/g pectin OHC, low moisture, ash and protein content of 6.85 ± 0.10%, 3.87 ± 0.10% and 2.61 ± 0.06% respectively, which can be utilized as a food additive. Therefore, pectin extraction from Citrus limetta peel using a greener technique like MAE is an eco-friendly, time-saving approach to transform waste into a versatile food additive.

Recent advances on physical technologies for the pretreatment of food waste and lignocellulosic residues

The complete deployment of a bio-based economy is essential to meet the United Nations' Sustainable Development Goals from the 2030 Agenda. In this context, food waste and lignocellulosic residues are considered low-cost feedstocks for obtaining industrially attractive products through biological processes. The effective conversion of these raw materials is, however, still challenging, since they are recalcitrant to bioprocessing and must be first treated to alter their physicochemical properties and ease the accessibility to their structural components. Among the full pallet of pretreatments, physical methods are recognised to have a high potential to transform food waste and lignocellulosic residues. This review provides a critical discussion about the recent advances on milling, extrusion, ultrasound, and microwave pretreatments. Their mechanisms and modes of application are analysed and the main drawbacks and limitations for their use at an industrial scale are discussed.

Upstream processes of citrus fruit waste biorefinery for complete valorization

Citrus fruit waste (CW) is a useful biomass and its valorization into fuels and biochemicals has received much attention. For economic feasibility, increased efficiency of the preceding extraction and enzyme saccharification processes is necessary. However, at present, there is a lack of systematic reviews addressing these two integral upstream processes in concert for CW biorefinery. Here, the state-of-the-art advancements in enzyme extraction and saccharification processes-using which relevant essential oils, flavonoids, and sugars can be obtained-are reviewed. Specifically, the extraction options for two commercially available CW-derived products, essential oils and pectin, are discussed. With respect to enzyme saccharification, the use of an undefined commercial mixture routinely results in suboptimal sugar production. In this respect, applicable strategies for enzyme mixture customization are suggested for maximizing the hydrolytic efficiency of CW. The enzyme degradation system for CW-derived carbohydrates and its extensive application for sugar production are also discussed.

Cardioprotective Effects of Grapefruit IntegroPectin Extracted via Hydrodynamic Cavitation from By-Products of Citrus Fruits Industry: Role of Mitochondrial Potassium Channels

Citrus flavonoids are well-known for their beneficial effects at the cardiovascular and cardio-metabolic level, but often the encouraging in vitro results are not confirmed by in vivo approaches; in addition, the clinical trials are also inconsistent. Their limited bioavailability can be, at least in part, the reason for these discrepancies. Therefore, many efforts have been made towards the improvement of their bioavailability. Hydrodynamic cavitation methods were successfully applied to the extraction of byproducts of the Citrus fruits industry, showing high process yields and affording stable phytocomplexes, known as IntegroPectin, endowed with great amounts of bioactive compounds and high water solubility. The cardioprotective effects of grapefruit IntegroPectin were evaluated by an ex vivo ischemia/reperfusion protocol. Further pharmacological characterization was carried out to assess the involvement of mitochondrial potassium channels. Grapefruit IntegroPectin, where naringin represented 98% of the flavonoids, showed anti-ischemic cardioprotective activity, which was better than pure naringenin (the bioactive aglycone of naringin). On cardiac-isolated mitochondria, this extract confirmed that naringenin/naringin were involved in the activation of mitochondrial potassium channels. The hydrodynamic cavitation-based extraction confirmed a valuable opportunity for the exploitation of Citrus fruits waste, with the end product presenting high levels of Citrus flavonoids and improved bioaccessibility that enhances its nutraceutical and economic value.