Exploring hydrodynamic cavitation for citrus waste valorisation in Malta: from beverage enhancement to potato sprouting suppression and water remediation.

Introduction: The endorsement of circular economy, zero-waste, and sustainable development by the EU and UN has promoted non-thermal technologies in agro-food and health industries. While northern European countries rapidly integrate these technologies, their implementation in Mediterranean food-supply chains remains uncertain. Aims: We evaluated the usefulness of hydrodynamic cavitation (HC) for valorizing orange peel waste in the fresh orange juice supply chain of the Maltese Islands. Method: We assessed: a) the effectiveness of HC in extracting bioactive compounds from orange peels (Citrus sinensis) in water (35°C) and 70% (v/v) ethanol (-10°C) over time, compared to conventional maceration, and b) the potato sprouting-suppression and biosorbent potential of the processed peel for copper, nitrate, and nitrite binding. Results: Prolonged HC-assisted extractions in water (high cavitation numbers), damaged and/or oxidized bioactive compounds, with flavonoids and ascorbic acid being more sensitive, whereas cold ethanolic extractions preserved the compounds involved in radical scavenging. HC-processing adequately modified the peel, enabling its use as a potato suppressant and biosorbent for copper, nitrate, and nitrite. Conclusion: Coupling HC-assisted bioactive compound extractions with using leftover peel for potato-sprouting prevention and as biosorbent for water pollutant removal offers a straightforward approach to promoting circular economic practices and sustainable agriculture in Malta.

Pressurized liquid extraction assisted by high-intensity ultrasound to obtain hesperidin from lime waste: Integration of in-line purification and on-line chromatographic analysis.

Hesperidin is a phenolic compound usually found in citrus fruits, which is known for its anti-inflammatory and antioxidant properties. This bioactive compound has already been used to formulate medications to treat chronic venous insufficiency. In this work, through a system which allows the in-line coupling of the pressurized liquid extraction (PLE) and high-intensity ultrasound (HIUS) with solid phase extraction (SPE), and analysis by high-performance liquid chromatography with UV-Vis detector (HPLC-UV) in on-line mode, a method was developed to obtain, separate, and quantify hesperidin from the industrial waste of lime. An eco-friendly approach with water and ethanol as extraction solvents was used. Parameters such as temperature (80, 100, and 120 °C) and HIUS power (0, 200, and 400 W) were evaluated regarding hesperidin yield. In this context, the higher hesperidin yield (18.25 ± 1.52 mg/g) was achieved using water at a subcritical state (120 °C and 15 MPa). The adsorbent SepraTM C-18-E isolated hesperidin from the other extracted compounds employing 50% ethanol in the SPE elution. The possibility ofon-lineanalysis coupling a high-performance liquid chromatograph to an ultraviolet detector (HPLC-UV) system was studied and shown to be a feasible approach for developing integrated technologies. Conventional extractions and their antioxidant capacities were evaluated, highlighting the advantages of the HIUS-PLE-SPE extractive method. Furthermore, the on-linechromatographic analysis showed the potential of the HIUS-PLE-SPE- HPLC-UV system to quantify the extracted compounds in real time.

Thermophilic biocatalysts for one-step conversion of citrus waste into lactic acid.

Agri-food residues offer significant potential as a raw material for the production of L-lactic acid through microbial fermentation. Weizmannia coagulans, previously known as Bacillus coagulans, is a spore-forming, lactic acid-producing, gram-positive, with known probiotic and prebiotic properties. This study aimed to evaluate the feasibility of utilizing untreated citrus waste as a sustainable feedstock for the production of L-lactic acid in a one-step process, by using the strain W. coagulans MA-13. By employing a thermophilic enzymatic cocktail (Cellic CTec2) in conjunction with the hydrolytic capabilities of MA-13, biomass degradation was enhanced by up to 62%. Moreover, batch and fed-batch fermentation experiments demonstrated the complete fermentation of glucose into L-lactic acid, achieving a concentration of up to 44.8 g/L. These results point to MA-13 as a microbial cell factory for one-step production of L-lactic acid, by combining cost-effective saccharification with MA-13 fermentative performance, on agri-food wastes. Moreover, the potential of this approach for sustainable valorization of agricultural waste streams is successfully proven. KEY POINTS: • Valorization of citrus waste, an abundant residue in Mediterranean countries. • Sustainable production of the L-( +)-lactic acid in one-step process. • Enzymatic pretreatment is a valuable alternative to the use of chemical.

Sweet Orange Juice Processing By-Product Extracts: A Caries Management Alternative to Chlorhexidine.

Dental caries is one of the most prevalent chronic diseases globally in both children and adults. This study investigated the potential of industrial sweet orange waste extracts (ISOWE) as a substitute for chlorhexidine (CHX) in managing dental caries. First, the cytotoxicity of ISOWE (40, 80, 120 mg/mL) and CHX (0.1 and 0.2%) on buccal epithelial cells was determined. ISOWE exhibited no overall toxicity, whereas CHX strongly affected cell viability. The combination of ISOWE and CHX significantly enhanced cell proliferation compared to CHX alone. Next, the antimicrobial efficacy of ISOWE, CHX, and their combination was assessed against a 7-day complex biofilm model inoculated with oral samples from human volunteers. CHX exhibited indiscriminate antimicrobial action, affecting both pathogenic and health-associated oral microorganisms. ISOWE demonstrated lower antimicrobial efficacy than CHX but showed enhanced efficacy against pathogenic species while preserving the oral microbiome's balance. When applied to a cariogenic biofilm, the combined treatment of ISOWE with 0.1% CHX showed similar efficacy to 0.2% CHX treatment alone. Overall, the findings suggest that ISOWE is a promising natural anti-cariogenic agent with lower toxicity and enhanced selectivity for pathogenic species compared to CHX.

A Two-Step Approach to Orange Peel Waste Valorization: Consecutive Extraction of Pectin and Hesperidin.

Citrus consumption translates into large amounts of residue, the disposal of which is associated with environmental issues and high costs. Current trends in citrus waste focus on the extraction of highly valued bioactive compounds via single-compound extraction. There is a lack of knowledge on how these methodologies can be introduced into extraction schemes of bioactive compounds, maximizing the residue potential and reducing its amount. The present work aimed to address this issue by designing a consecutive extraction of pectin and hesperidin from orange peel waste. A novel method for extraction and precipitation of hesperidin with an eco-friendly approach is also presented. After neutral pretreatment, pectin extraction was conducted under acidic conditions, followed by hesperidin extraction with a drastic pH change. Pectin had a high AUA content (66.20 ± 1.25%), meeting the criteria for use in the food industry. The best-tested conditions for hesperidin extraction (30 min, 70 °C, 1:10 (w/v)) provided a yield of 1% and a purity of 84%. The designed extraction scheme shows the potential of citrus waste as a source of bioactive compounds of good quality and high interest in the food industry while following the principles of green chemistry and circular economy.

Appraisal of agroforestry biomass wastes for hydrogen production by an integrated process of fast pyrolysis and in line steam reforming.

The pyrolysis and in line steam reforming of different types of representative agroforestry biomass wastes (pine wood, citrus wastes and rice husk) was performed in a two-reactor system made up of a conical spouted bed and a fluidized bed. The pyrolysis step was carried out at 500 °C, and the steam reforming at 600 °C with a space time of 20 gcatalyst min gvolatiles-1 and a steam/biomass ratio (S/B) of 4. A study was conducted on the effect that the pyrolysis volatiles composition obtained with several biomasses has on the reforming conversion, product yields and H2 production. The different composition of the pyrolysis volatiles obtained with the three biomasses studied led to differences in the initial activity and, especially, in the catalyst deactivation rate. Initial conversions higher than 99% were obtained in all cases and the H2 production obtained varied in the 6.7-11.2 wt% range, depending on the feedstock used. The stability of the catalysts decreased depending on the feedstock as follows: pine wood â‰« citrus waste > rice husk. A detailed assessment of the mechanisms of catalyst deactivation revealed that coke deposition is the main cause of catalyst decay in all the runs. However, the volatile composition derived from the pyrolysis of citrus waste and rice husk involved the formation of an encapsulating coke, which severely blocked the catalyst pores, leading to catalyst deactivation during the first minutes of reaction.

Antibiofilm Efficacies of Flavonoid-Rich Sweet Orange Waste Extract against Dual-Species Biofilms.

The current study evaluated the antibacterial properties of industrial sweet orange waste extracts (ISOWEs), which are a rich source of flavonoids. The ISOWEs exhibited antibacterial activity towards the dental cariogenic pathogens Streptococcus mutans and Lactobacillus casei with 13.0 ± 2.0 and 20.0 ± 2.0 mg/mL for MIC (minimum inhibitory concentration) and 37.7 ± 1.5 and 43.3 ± 2.1 mg/mL for MBC (minimum bactericidal concentration), respectively. When evaluated in a 7-day dual-species oral biofilm model, ISOWEs dose-dependently reduced the viable bacteria count, and demonstrated strong synergistic effects when combined with the anti-septic chlorhexidine (at 0.1 and 0.2%). Similarly, confocal microscopy confirmed the anti-cariogenic properties of ISOWEs, alone and in combination with chlorhexidine. The citrus flavonoids contributed differently to these effects, with the flavones (nobiletin, tangeretin and sinensetin) demonstrating significantly lower MICs and MBCs compared to the flavanones hesperidin and narirutin. In conclusion, our study demonstrated the potential of citrus waste as a currently underutilised source of flavonoids for antimicrobial applications, such as in dental health.

Host-Guest Complexes HP-ß-CD/Citrus Antioxidants: Exploratory Evaluations of Enhanced Properties in Biodegradable Film Packaging.

The aim of this work was to exploit the antioxidant potential of molecules recovered during the pectin purification process of citrus lemon waste and to encapsulate them in stable pectin films, with a view to a green and circular economy process. Antioxidant molecules were recovered during the pectin purification process, further recovering matter from the waste. Seven molecules were identified and quantified, and the antioxidant power of the mixture and its stability over time was evaluated. To improve the stability of the bioactive fraction, this was complexed with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD); indeed, this procedure increased their thermal stability from 120 °C up to 250 °C, as verified by thermogravimetry. Furthermore, the most promising complexes were studied under autoclave-like conditions (120 °C, 28 min) to simulate thermal sterilization. The antioxidants and HP-ß-CD were combined in a pectin film, showing increased stability over time (up to three times) compared to uncomplexed antioxidants. This process represents a first step towards the development of applicable devices for the delivery of antioxidant molecules.

Characterization of the Dynamic Changes of Ruminal Microbiota Colonizing Citrus Pomace Waste during Rumen Incubation for Volatile Fatty Acid Production.

Rumen microorganisms are promising for efficient bioconversion of lignocellulosic wastes to biofuels and industrially relevant products. Investigating the dynamic changes of the rumen microbial community colonizing citrus pomace (CtP) will advance our understanding of the utilization of citrus processing waste by rumen fluid. Citrus pomace in nylon bags was incubated in the rumen of three ruminally cannulated Holstein cows for 1, 2, 4, 8, 12, 24, and 48 h. Results showed that total volatile fatty acids concentrations and proportions of valerate and isovalerate were increased over time during the first 12 h. Three major cellulose enzymes attached to CtP rose initially and then decreased during the 48-h incubation. Primary colonization happened during the initial hours of CtP incubation, and microbes compete to attach CtP for degrading easily digestible components and/or utilizing the waste. The 16S rRNA gene sequencing data revealed the diversity and structure of microbiota adhered to CtP were distinctly different at each time point. The increased abundance of Fibrobacterota, Rikenellaceae_RC9_gut_group, and Butyrivibrio may explain the elevated volatile fatty acids concentrations. This study highlighted key metabolically active microbial taxa colonizing citrus pomace in a 48-h in situ rumen incubation, which could have implications for promoting the biotechnological process of CtP. IMPORTANCE As a natural fermentation system, the rumen ecosystem of ruminants can efficiently degrade plant cellulose, indicating that the rumen microbiome offers an opportunity for anaerobic digestion to utilize biomass wastes containing cellulose. Knowledge of the response of the in situ microbial community to citrus pomace during anaerobic fermentation will help improve the current understanding of citrus biomass waste utilization. Our results demonstrated that a highly diverse rumen bacterial community colonized citrus pomace rapidly and continuously changed during a 48-h incubation period. These findings may provide a deep understanding of constructing, manipulating, and enriching rumen microorganisms to improve the anaerobic fermentation efficiency of citrus pomace.

Functional Ingredients and Additives from Lemon by-Products and Their Applications in Food Preservation: A Review.

Citrus trees are among the most abundant fruit trees in the world, with an annual production of around 124 million tonnes. Lemons and limes are among the most significant contributors, producing nearly 16 million tonnes per year. The processing and consumption of citrus fruits generates a significant amount of waste, including peels, pulp, seeds, and pomace, which represents about 50% of the fresh fruit. Citrus limon (C. limon) by-products are composed of significant amounts of bioactive compounds, such as phenolic compounds, carotenoids, vitamins, essential oils, and fibres, which give them nutritional value and health benefits such as antimicrobial and antioxidant properties. These by-products, which are typically discarded as waste in the environment, can be explored to produce new functional ingredients, a desirable approach from a circular economy perspective. The present review systematically summarizes the potential high-biological-value components extracted from by-products to achieve a zero-waste goal, focusing on the recovery of three main fractions: essential oils, phenolic compounds, and dietary fibres, present in C. limon by-products, and their applications in food preservation.

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.

Application of Citrus By-Products in the Production of Active Food Packaging.

Some citrus by-products such as orange peel contains valuable compounds that could be recovered and restored into the food chain. In this study, an efficient valorization of orange peel has been investigated using green extraction, fractionation, and impregnation techniques. The first step included its extraction using CO2 and ethanol under different pressure (200-400 bar) and temperature (35-55 °C) conditions. The extracts obtained at 300 bar and 45 °C showed strong antioxidant with moderate antimicrobial activity. Then, the extract was subjected to a sequential fractionation process. The fraction obtained at 300 bar, 45 °C, and using 32% ethanol showed the strongest antioxidant and antimicrobial activity with a high extraction yield. Finally, the potential of the two best extracts (obtained at 400 bar and 45 °C before any fractionation and the fractions obtained at 300 bar, 45 °C using 32% ethanol) was determined by conducting an impregnation process to obtain an antioxidant food-grade rigid plastic that would preserve fresh food. The percentage of cosolvent (1 and 2% ethanol), the impregnation time (1 and 3 h), the pressure (200 and 400 bar), and the temperature (35 and 55 °C) were evaluated as variables of this process. The impregnated plastic showed good antioxidant and antimicrobial activities.

Metabolomic navigated Citrus waste repurposing to restore amino acids disorder in neural lesion.

The fruit juice food industry produces huge waste annually, mainly Citrus peel and seeds. We investigated their chemical composition using hydrophilic interaction chromatography (HILIC-) and reverse phase liquid chromatography tandem mass spectrometry (RPLC-MS/MS), revealing 277 compounds, mainly containing flavonoids and limonoids. As the primary representative component in Citrus waste, limonin was selected to be explored new bio-functions. We applied Zebrafish larvae to study the metabolomic response invoked by limonin. The differential metabolites (DMs) varied depending on the exposing concentration of limonin. Enrichment analysis indicated that the identified DMs related to inflammation and neurologic disorders, including epilepsy which were newly discovered for limonoids and Citrus waste. Limonin was found to restore amino acids disorder to take neuroprotection against epilepsy. Our findings provided a new bio-function and purpose for Citrus waste and limonoids. Also, we demonstrated a concise case to repurpose food waste for new applications under metabolome investigation.

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

Globally the generation and mismanagement of waste from fruit processing and post-harvest impose a severe burden on waste management strategies along with environmental pollution, health hazards. Citrus waste is one of such worrying fruit waste, which is rich in several value-added chemicals, including pectin. Pectin is a prebiotic polysaccharide possessing a multitude of health benefits. Citrus pectin has excellent gelling, thickening, water holding capacity, and encapsulating properties, which pave its functionality in versatile industrial fields including food processing and preservation, drug and therapeutic agents, cosmetics, and personal care products. The utilization of citrus wastes to derive valuable bioproducts can offer an effective approach towards sustainable waste management. With the ever-increasing demand, several strategies have been devised to increase the efficiency of pectin recovery from citrus waste. This review article discusses the sources, effect, and technology-mediated valorization of citrus waste, the functional and nutritive application of pectin along with its socio-economic and environmental perspective.

Integrated biorefinery approach to valorize citrus waste: A sustainable solution for resource recovery and environmental management.

Citrus fruits are extensively cultivated, consumed and major processed horticulture crops around the globe. High processing and consumption generate huge quantities of solid organic wastes. Citrus waste represents approximately 40-50% of total fruit weight, which consists of rag (membranes and cores), pulp, seeds, and peel (albedo and flavedo), which are a potential source of value-added products including essential oils, carotenoids, pectin, dietary fibers, and polyphenols biofuel, etc. However, waste produced is discarded as waste in the environment, which causes a serious threat due to the presence of bioactive compounds. Recent research strategies on the integrated biorefinery approach explore various ways to utilize the waste obtained from the citrus wastes for their subsequent recovery of value-added products. Moreover, the citrus waste can be turned into various bio-products, viz., enzymes, biofuels, and biopolymers using the integrated biorefinery approach, which can optimize the development of green waste for sustainability and economic benefits. Given the sustainable solution for resource recovery and environmental management, the article reviews the latest advances in the novel valorization approach and valuation of the existing state-of-the-art green technologies for citrus waste utilization to bring a sustainable solution for increasing demand for food, fuel, and energy security. To achieve the zero-waste approach and industrial viability, more efforts should be given to scale-up green recovery techniques along with diverse product profiling.

Preparation of Multifunctional N-Doped Carbon Quantum Dots from Citrus clementina Peel: Investigating Targeted Pharmacological Activities and the Potential Application for Fe3+ Sensing.

Carbon quantum dots (CQDs) have recently emerged as innovative theranostic nanomaterials, enabling fast and effective diagnosis and treatment. In this study, a facile hydrothermal approach for N-doped biomass-derived CQDs preparation from Citrus clementina peel and amino acids glycine (Gly) and arginine (Arg) has been presented. The gradual increase in the N-dopant (amino acids) nitrogen content increased the quantum yield of synthesized CQDs. The prepared CQDs exhibited good biocompatibility, stability in aqueous, and high ionic strength media, similar optical properties, while differences were observed regarding the structural and chemical diversity, and biological and antioxidant activity. The antiproliferative effect of CQD@Gly against pancreatic cancer cell lines (CFPAC-1) was observed. At the same time, CQD@Arg has demonstrated the highest quantum yield and antioxidant activity by DPPH scavenging radical method of 81.39 ± 0.39% and has been further used for the ion sensing and cellular imaging of cancer cells. The obtained results have demonstrated selective response toward Fe3+ detection, with linear response ranging from 7.0 µmol dm-3 to 50.0 µmol dm-3 with R2 = 0.9931 and limit of detection (LOD) of 4.57 ± 0.27 µmol dm-3. This research could be a good example of sustainable biomass waste utilization with potential for biomedical analysis and ion sensing applications.

The impact of pyrolysis conditions on orange peel biochar physicochemical properties for sandy soil.

The citrus industry is considered one of the main contributors to agricultural waste. Peels are commonly used in the food industry or as feedstock in biorefining. In this study, the potential of waste orange peel biochar for agricultural applications in sandy soil was investigated. This will not only increase the percentage of agricultural waste recycling, but also lead to more sustainable agriculture with environmental benefits such as carbon sequestration. Biochar was produced through slow pyrolysis in the temperature range 300-600°C and at two holding durations (10 min and 60 min). Both factors had a significant impact on the physicochemical characteristics of biochar in the heating region 300-450°C. However, varying the holding time for pyrolysis temperatures beyond 450°C had a diminishing effect on biochar properties compared with the impact of increasing pyrolysis temperature. The study also looked at certain properties that are specific to agricultural application not previously reported for orange peel. Very high cation exchange capacities of 70 cmol kg-1 were achieved at 300°C, whereas water holding capacity was not strongly influenced by pyrolysis conditions. Preliminary planting tests indicate potential for improving agricultural sustainability in sandy soils. The technoeconomic analysis of biochar showed that the pyrolysis process can be profitable with sufficient plant capacity.

Antimicrobial activity of orange juice processing waste in powder form and its suitability to produce antimicrobial packaging.

Orange peel essential oil is a common value-added product from orange juice processing waste. It is antimicrobial and used to produce antimicrobial films and coatings. This study reports the first development of antimicrobial films using orange peel as powder (OPP) instead of the extracted essential oil. The OPP amount needed for antimicrobial films was determined by studying the OPP effects on conidia germination inhibition (minimum inhibitory concentration (MIC)) and mycelial growth reduction for Botrytis cinerea, Aspergillus niger, and Penicillium sp. This amount was incorporated into linear low-density polyethylene using plastic processing machinery. The resulting LLDPE/OPP composite film was characterized for antimicrobial activity against Botrytis cinerea, antimicrobial compound release, and mechanical, barrier, and optical properties. We found the same OPP MIC (8.4 mg OPP/mL air) for the three fungi although their mycelial growth kinetics and conidia germination inhibition periods varied with OPP amount differently. 21.1 mg OPP/mL air completely inhibited the germination of Penicillium sp., B. cinerea, and A. niger conidia for 3, 2, and 1 days. The antimicrobial film was a LLDPE/OPP composite with 46% plastic replacement that reduced B. cinerea growth by 30% over a 7-day storage period at 23 °C, less than OPP due to limonene/citral reduction during processing. Plastic replacement resulted in films with the barrier and mechanical properties of plastics commonly used in food packaging. This study demonstrates the OPP antimicrobial capacity against food spoilage microorganisms and its suitability to produce antimicrobial packaging for food applications and presents a novel approach to utilizing orange juice processing waste.

High Biological Value Compounds Extraction from Citrus Waste with Non-Conventional Methods.

Citrus fruits are extensively grown and much consumed around the world. Eighteen percent of total citrus cultivars are destined for industrial processes, and as a consequence, large amounts of waste are generated. Citrus waste is a potential source of high biological value compounds, which can be used in the food, pharmaceutical, and cosmetic industries but whose final disposal may pose a problem due to economic and environmental factors. At the same time, the emerging need to reduce the environmental impact of citrus waste and its responsible management has increased. For these reasons, the study of the use of non-conventional methods to extract high biological value compounds such as carotenoids, polyphenols, essential oils, and pectins from this type of waste has become more urgent in recent years. In this review, the effectiveness of technologies such as ultrasound assisted extraction, microwave assisted extraction, supercritical fluid extraction, pressurized water extraction, pulsed electric field, high-voltage electric discharges, and high hydrostatic pressures is described and assessed. A wide range of information concerning the principal non-conventional methods employed to obtain high-biological-value compounds from citrus waste as well as the most influencing factors about each technology are considered.

Bio-sorbents, industrially important chemicals and novel materials from citrus processing waste as a sustainable and renewable bioresource: A review.

Citrus waste includes peels, pulp and membrane residue and seeds, constituting approximately 40-60% of the whole fruit. This amount exceeds ~110-120 million tons annually worldwide. Recent investigations have been focused on developing newer techniques to explore various applications of the chemicals obtained from the citrus wastes. The organic acids obtained from citrus waste can be utilized in developing biodegradable polymers and functional materials for food processing, chemical and pharmaceutical industries. The peel microstructures have been investigated to create bio-inspired materials. The peel residue can be processed to produce fibers and fabrics, 3D printed materials, carbon nanodots for bio-imaging, energy storage materials and nanostructured materials for various applications so as to leave no waste at all. The article reviews recent advances in scientific investigations to produce valuable products from citrus wastes and possibilities of innovating future materials and promote zero remaining waste for a cleaner environment for future generation.