The Prospects of Mango ( Mangifera indica ) Fruit Wastes for Renewable Biofuel Production: A Review

Abstract

Fossil fuel has remained a dominant energy source worldwide, despite being among the leading contributors to environmental pollution and greenhouse gas emissions. Climate change, shortage of energy supplies, unsustainable prices, and supply constraints have made energy availability and security extremely problematic. Thus, there is a growing global consensus that renewable energy sources should replace fossil fuels to reduce environmental pollution and greenhouse gas emissions which pose severe threat to the ecosystem and cause climate change and global warming. Among these, biofuels including bioethanol, biodiesel, and biogas are renewable energy sources produced from a wide range of biomass materials. Biofuel is chosen as the best option as it offers the dual advantage of providing green energy while simultaneously reducing environmental waste. The present review delves into recently published articles, and book chapters about biofuels from a variety of reliable sources including Google Scholar, ScienceDirect, Web of Science, PubMed, Elsevier and Scopus. A total of 89 articles published between 2020–2025 were examined. Mendeley software (2016 version) was used to manage the references including organizing citations, ensuring consistent formatting, and automatically generating the reference list according to the required style. Mango waste's biochemical composition, energy conversion, technical advancement, environmental benefits, and scalability issues have been well considered in this assessment. This review evaluates the potential of mango waste as a suitable biomass feedstock for renewable energy production. Findings indicate that mango waste, including peels, seeds, and pulp contains 60%–70% carbohydrate which is potential for bioethanol, biodiesel, and biogas (methane 45% - 60%) production. The study examined biofuels generation from mango wastes and to determine their potential as renewable energy sources, advantages to the environment and economy, technological developments as well as issues with production, and scalability for sustainable energy solutions.

Introduction

The global demand for energy keeps increasing due to population increase, rapid growth in transport sector and industrialization. ¹ Fossil fuels including coal, natural gas, and oil have been the main sources of this energy for decades. ² However, fossil fuels are linked to environmental degradation, climate change, and extreme weather patterns. ³ Fossil fuels have driven industrial progress but also harm ecosystems and public health thus, addressing energy demands and environmental protection is very important. ⁴ The continued consumption of fossil fuels has resulted in major economic and environmental issues such as air pollution, global warming, greenhouse gas emissions, and energy source depletion. ⁵ Fossil fuels mining and refinement also degrade the ecosystem by causing habitat damage, oil spills, and deforestation. ⁶ Furthermore, an over-reliance on petroleum and hydrocarbons sources of energy cause damage to the ozone layer, releasing hazardous compounds, and dangerous pollutants all of which contribute to global warming. ⁷ The side effects carry significant health hazards such as lung cancer, chronic obstructive pulmonary disease, acute respiratory infections, and problems relating to the eyes.^7,8 Besides, reports indicate that global energy demand has risen consistently over the years, with fossil fuels historically supplying most of the required energy. However, the finite nature of these resources poses a significant challenge as projections suggest that fossil fuel reserves may be depleted by the mid-to-late twenty-first century with some estimates indicating a potential exhaustion of economically viable reserves by around 2050. ⁹ To address these issues, biofuel production from renewable energy sources such as agricultural wastes, fruit wastes, non-edible feedstocks, and bamboo juice has gained global attention.^10,11 Bioethanol is now one of the most researched biofuels in the world because it has the potential to be a sustainable substitute for fossil fuels. ⁵ Bioethanol emits less carbon dioxide and lessens the reliance on the limited supply of fossil fuels. ¹² One promising feedstock for bioethanol production is mango wastes such as mango peels, seeds, rejects and rotten mango which are rich in fermentable sugars, making it excellent feedstocks for bioethanol production through microbial fermentation and distillation.

Mangoes, originating from South Asia, are a widely grown tropical fruit with significant production and consumption in various regions, making them one of the most extensively farmed tropical and subtropical fruits globally^13–15 The five leading mango-producing nations in the world are India, China, Indonesia, Thailand, and Pakistan. ¹⁶ India is the world's largest mango producer, accounting for nearly 50% of global production with approximately 18,431.3 thousand metric tons of mangoes. ¹⁷ Mango grows well in tropical and subtropical climates with optimal growth temperatures between 24–30 °C, and annual rainfall of 750–2500 mm. ¹⁸

It is estimated that 58.65 million metric tonnes of mangoes were produced worldwide between 2021 and 2023 and are expected to rise to 65 million metric tonnes by 2026. ¹⁹ Its increasing availability in these regions along with growing awareness of its nutritional benefits have led to a steady rise in its global consumption. ²⁰

The consumption demand is noticeable in both fresh fruit markets and processed goods including juices, desserts and dried mangoes. ²¹ Countries with high mango production and consumption produce significant wastes at the post-consumer level and throughout the supply chain (harvest losses and transportation damage and storage). ²² About 30–50% of the weight of mango fruits is discarded as wastes and these results to 23.6 million metric tons of mango wastes generated annually.^23,24 The main components of mango wastes are peels, seeds, pulp leftovers, and spoilt mangoes which can be found considerably at processing areas, marketplaces, homes, and storage areas. ²¹ Improper management and disposal of mango wastes contribute to environmental concerns such as methane emissions, air pollution and water pollution from its decomposition. ²⁵ However, these waste materials hold economic and environmental potential if repurposed for value-added products such as bioethanol, biodiesel and biogas. Mango peels, seeds, and rotten mangoes are potential bioethanol raw materials due to their high cellulose and hemicellulose content which are easily hydrolysed into fermentable sugars. ²⁶ It is imperative to address waste management as mango production and consumption increases. By converting mango wastes into biofuels like bioethanol, biodiesel, and biogas, a sustainable energy source with a smaller environmental impact can be produced. ²⁷ Mango wastes may be recycled into natural dyes, nutritious supplements, and biodegradable packaging which help to make the mango supply chain more sustainable and profitable. ²⁸ Moreover, mango processing wastes, such as peels and seeds, can be repurposed in several ways to enhance sustainability. Dried mango peels and seed kernels can be incorporated into animal feed formulations, providing an inexpensive source of energy and nutrients while reducing reliance on conventional feed crops, thereby avoiding competition with human food sources. ²⁹ Similarly, composting or converting mango residues into organic fertilizers enriches soil health and reduces dependence on chemical fertilizers, supporting eco-friendly farming practices. ³⁰ By channelling these by-products into animal nutrition and agriculture, mango waste management not only minimizes environmental pollution but also promotes circular resource use, helping ensure long-term sustainability. In addition, the potential of mango waste is yet to be seriously recognised, despite their abundance worldwide, although they have the potential to be utilized in biofuel production. The present study examines the ways in which waste materials from mangos including peels, seeds, and pulp residues, can be efficiently used to produce bioethanol, biodiesel and biogas as alternative energy sources to fossil fuels. This review article presents a novel perspective on valorising mango postharvest losses by exploring the potential of converting mango fruit waste into biofuels, thereby addressing food waste, energy sustainability, and environmental concerns simultaneously. The present study highlights the value of mango waste biomass as feedstock for biofuel production, emphasizing its environmental, economic, and scalability aspects. It positions mango waste and natural additives such as millet and sorghum as a strategic resource for improving bioethanol yield, contributing to sustainable biofuel initiatives and the development of a circular bio-economy.

Mango Waste Management for Sustainable Bioethanol Production

Mango fruits are a highly perishable commodity, with postharvest losses ranging from 30% to over 80% globally, particularly in developing countries. ³¹ These losses not only result in economic losses for farmers and processors but also contribute to food waste and environmental degradation. ³¹ However, mango fruit waste can be valorised by converting it into biofuels, offering a sustainable alternative to fossil fuels. ³² By harnessing the potential of mango waste, biofuels such as biogas, bioethanol, or biodiesel can be produced, reducing dependence on fossil fuels and mitigating greenhouse gas emissions. This approach can promote a circular economy, minimize waste disposal issues, and provide a renewable energy source, ultimately contributing to a more sustainable ecosystem and energy future. Mango wastes including peels, seeds and rotten mango have high amount of cellulose and hemicelluloses contents that can be easily hydrolysed in fermentable sugar for bioethanol production. ³³ However, mango cellulose and hemicelluloses can be hydrolysed through employing several stages, each playing a crucial role in transforming raw materials into usable bioethanol. ²⁶ These stages include pre-treatment, hydrolysis, fermentation, and distillation with enzymatic hydrolysis playing a key role in enhancing sugar release for fermentation. ³⁴ A study shows that pre-treatment of mango waste using chemicals such as dilute sulphuric acid and sodium hydroxide yielded substantial amount of reducing sugar for bioethanol production. ³⁵ Approximately 31.29% of reducing sugar was produced from mango peels treated with dilute sulfuric acid. ³³ However, the use of chemicals in the pre-treatment of mango waste can be harmful to the environment due to their corrosive nature. Additionally, chemicals are expensive thus, may not be affordable for low-income communities, making the process expensive and unsustainable. Still, mango waste cellulose and hemicelluloses can be released using enzymatic hydrolysis, potentially utilizing enzymes from Saccharomyces cerevisiae. ³⁶ Enzymatic hydrolysis and fermentation using Saccharomyces cerevisiae offers eco-friendly, cost-effective, and environmentally friendly alternatives to chemical pre-treatment, aligning with the circular economy and green technology principles. ³⁷ Therefore, safer and more cost-effective alternative to corrosive chemicals used in pre-treatment can be employed, such as the use of naturally occurring enzymes in grains like sorghum and millet. ³⁸ Research reported that diluted mango waste juice supplemented with sorghum yielded 15% bioethanol, whereas mango juice supplemented with millet flour yielded 20% bioethanol.^38,39 Studies reveal different bioethanol yields from mango waste under different treatment conditions. For instance, fermentation of mango pulp treated with 3 g/L of yeast at 30 °C produced 15% (v/v) bioethanol while mango peel treated with alkali and yeast yielded up to 49% (v/v) bioethanol. ⁴⁰ Temperature significantly influences bioethanol production with lower temperatures generally resulting in higher bioethanol concentrations while elevated temperatures tend to reduce yield. Bioethanol yields varied with temperature, reaching 8.7% at 30 °C, 7.42% at 32 °C, and 7.2% at room temperature (28 °C). ⁴¹ Moreover, the concentration of yeast used during fermentation significantly influences bioethanol production as higher or optimized yeast levels may enhance the rate of sugar conversion to bioethanol while insufficient or excessive yeast concentrations can lead to suboptimal fermentation efficiency and reduced bioethanol yield. Yeast concentration of 1 g/L yielded 7.81% bioethanol while a concentration of 3 g/L produced 7.96% and the highest bioethanol yield of 8.11% was achieved with a yeast concentration of 5 g/L, ⁴¹ indicating a positive correlation between yeast concentration and bioethanol production. Thus, the higher the yeast concentration the higher the bioethanol yields from fermented juice. Besides, chemical pre-treatment methods, including acidic and alkaline hydrolysis pose risks of soil and water contamination, equipment corrosion, and worker health issues due to hazardous chemicals. ⁴² Bioethanol production from fruit wastes is water-intensive, straining resources, and distillation consume substantial energy. ⁴³ However, bioethanol production from mango waste under controlled temperature, yeast concentration and the use of chemicals such as sulphuric acids is costly and not environmentally friendly thus, using natural additives such as sorghum and millet reduce the cost and protect the environment because they contain enzymes which play role in hydrolysis.^39,44 Still, a study show that the use of naturally derived enzymes from fruits (mango amylase) helps to reduce cost and is environmentally friendly. ⁴⁵ The selection of additives was guided by optimization experiments, which showed that adding 30 g of additives per litre of fermenting juice produced promising results. ¹¹

Bioethanol is a significant renewable energy source because of its many applications. Its main application in the transportation industry is as a gasoline additive, frequently mixed with petrol in ratios like E10 and E85 to lower greenhouse gas emissions and dependency on fossil fuels. ⁴⁶ Flex-fuel cars are specifically made to run on greater percentages of bioethanol, such as E85, and bioethanol also acts as an octane enhancer, which boosts engine efficiency and performance. ⁴⁷ Compared to fossil fuels, which emit higher levels of sulphur oxides, carbon monoxide, carbon dioxide, nitrogen oxides, and particulate matter into the atmosphere, contributing significantly to air pollution, greenhouse gas accumulation, acid rain, and respiratory health problems in humans. ⁴⁸ In addition to being utilised for transportation, bioethanol is also used to generate energy. It can be burned directly in thermal power plants or mixed with other fuels to create electricity. ⁴⁹ Additionally, it offers a clean burning alternative for heaters, lamps and stoves, particularly in rural regions. ⁵⁰ Because of its antibacterial qualities, bioethanol is used extensively in sanitisers and disinfectants. ⁵¹ It also serves as a feedstock for chemicals like acetic acid and ethyl acetate and as a solvent in the manufacturing of paints, varnishes, cosmetics, and medications. ⁵² At the household level, it provides a cleaner and safer option for cooking in ethanol stoves and is also utilised in fireplaces that leave little smoke or residue behind. ⁵³ Because bioethanol is made from renewable resources, it helps the environment by reducing reliance on fossil fuels, lowering carbon monoxide and particulate matter emissions, and promoting sustainable energy systems. ⁴⁹ Additionally, it benefits agriculture and rural development by creating new markets for fruit wastes, while also generating employment opportunities in the biofuel production industry. ⁵⁴

Therefore, utilizing cost-effective methods such as fermenting mango waste by employing natural enzymes from grains like sorghum and millet presents a viable alternative, reducing production costs. It is a significant substitute biofuel for fossil fuel sources that has positive environmental effects like lower greenhouse gas emissions.

Biodiesel from mango Seeds as an Alternative Renewable Bioenergy

Biodiesel produced from vegetable oils, animal fats, or waste cooking oils, is widely regarded as one of the most promising and reliable renewable energy sources for the future. ⁴⁵ There are more than 350 oil-bearing crops that have been identified as suitable for use in biodiesel production, offering a wide range of options for sustainable fuel development across different regions and climates. ⁵⁵ However, biodiesel production from food crops such as soybean, maize, or sunflower may create competition between food and fuel demands. ⁴⁵ Therefore, agricultural waste offers a sustainable alternative for biodiesel production, reducing reliance on food crops and minimizing environmental impact. ⁵⁶ Among various agricultural residues, mango waste stands out as a promising source for biodiesel production due to its oil content and availability. ⁵⁷ Studies have reported that mango seed contains between 12% and 15% oil which is potential for biodiesel production. ⁵⁷ The most widely used process for producing biodiesel is transesterification, which produces the biodiesel and the valuable by-product glycerol when triglycerides found in oils or fats combine with an alcohol, typically methanol or ethanol, in the presence of a catalyst. ⁴⁵ The production process of biodiesel typically involves multiple steps: first, the feedstock is prepared by filtering oils or fats to remove impurities; next, a catalyst is added often sodium hydroxide (NaOH), or potassium hydroxide (KOH), is added along with an alcohol like methanol to initiate the transesterification process, where triglycerides are broken down into methyl esters (biodiesel) and glycerol as a by-product; third, oils are trans esterified to produce biodiesel; fourth, the biodiesel is separated from glycerol; and lastly, it is purified by washing and drying before being used as fuel. ⁴⁵ Catalysts, which can be generically categorised as chemical or biological, are essential in improving the efficiency of biodiesel production process. ⁵⁸ The most prevalent and effective chemical catalysts for processing feedstocks with low free fatty acid (FFA) and its concentrations are alkaline types, such as NaOH, KOH, and sodium methoxide. ⁵⁸ Although they react more slowly than alkaline catalysts, acid catalysts such as sulphuric acid (H₂SO₄) and hydrochloric acid (HCl) are more appropriate for oils with high FFA levels. ⁵⁹ While heterogeneous catalysts, such zeolites and solid oxides (CaO, MgO), offer benefits like simple separation and reusability, their reaction rates are frequently slower. ⁶⁰ However, the use of these chemicals is costly and environmentally unfriendly and biological catalysts primarily lipase enzymes provide a more adaptable and environmentally friendly choice. ⁶¹

Biodiesel in diesel engines may be used in its pure form, blended in various ratios, or as a fuel additive to enhance performance and extend engine lifespan. ⁶² It is a mono-alkyl ester derived from the fatty acids present in vegetable oils and animal fats. Biodiesel is an important eco-friendly biofuel due to its biodegradability and relatively high flash point, typically around 150 °C. ⁶³ Also, biodiesel produces lower exhaust emissions, blends uniformly with petroleum diesel in any proportion, and offers excellent lubricating properties. ⁶² Even though biodiesels have some limitations like high viscosity and density, they were famous for their clean combustion characteristics, rich availability, renewability, sulphur free structure. ⁶⁴ Biodiesels can be enhanced by transesterification, blending with regular diesel or other additives, and sophisticated processing methods to get around drawbacks such high viscosity and density. ⁶⁵ These techniques improve overall performance and compatibility with contemporary engines while preserving its benefits, such as clean combustion, abundant availability, renewability, and sulfur-free composition. ⁶⁵

Biogas Production from mango Wastes as a Potential Source of Renewable Bioenergy

Biogas is a renewable energy source produced through anaerobic digestion (AD) of organic materials by microorganisms. ⁶⁶ The main components of biogas are methane (40-75%), carbon dioxide (25%–60%), hydrogen sulphide, and leftover nitrogen. ⁶⁷ The biological process of making biogas involves the breakdown of organic waste by microbes under anaerobic (oxygen-free) conditions. ⁶⁸ Biogas production involves four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. ⁶⁹ Hydrolytic bacteria break down complex organic molecules into simpler compounds, acidogenesis converts them into volatile fatty acids, acetogenesis stabilizes digestion, and methanogenesis converts acetic acid, hydrogen, and carbon dioxide into methane and water, determining the gas mixture's quality. ⁶⁹ The result is a combination of gases primarily made up of carbon dioxide (CO₂) and methane (CH₄), with trace amounts of hydrogen sulphide and water vapour. ⁶⁸ Biogas production may be restricted in a normal single-substrate digestion (only animal dung) by inhibitory chemicals, low carbon-to-nitrogen (C/N) ratio, or nutritional imbalances. ⁷⁰ Co-digesting multiple feedstocks, such as crop residues, food waste, agricultural by-products and Brewer's spent grain and cattle dung, can help balance carbon and nitrogen levels while addressing restrictions. ⁶⁷ Co-digestion of watermelon and mango yielded a greater biogas volume (5103 cm³) compared to digestion of mango alone (1533 cm³) or watermelon alone (2917 cm³). ⁷¹ Co-digestion is a beneficial method for biogas production due to its ability to optimize nutrient balance, reduce toxicity, and improve efficiency. ⁷² It involves combining different substrates with varying nutrient compositions, creating a balanced carbon-to-nitrogen ratio, diluting inhibitory compounds, and increasing methane yield. ⁷³ It also supports better waste management by treating agricultural, industrial, and municipal organic waste simultaneously. ⁷³

The AD is commonly employed to treat agricultural and organic industrial waste with particular emphasis on by-products from fruit processing industries. ⁷⁴ The AD process offers numerous benefits including reduced greenhouse gases (GHGs) emissions, production of digestate for agricultural use, a small spatial footprint, and the generation of high-quality renewable fuel. ³⁸ A report indicates that biogas can be produced from a wide range of organic feedstocks including cow dung, poultry litter, pig manure, and agricultural waste such as crop residues vegetable scraps and fruit wastes like mango wastes. ⁷⁵ The production of biogas from mono-digestion substrates is frequently constrained by ammonia accumulation and an unbalanced carbon-to-nitrogen (C/N) ratio. ⁷⁶ Biogas production can be greatly increased by co-digesting agricultural wastes, pig manure, poultry litter, and cow dung. ⁶⁶ These various organic materials can be combined to optimise the feedstock mixture's carbon-to-nitrogen (C/N) ratio and nutrient balance, enhancing microbial activity during AD. ⁷⁷ By improving C/N ratio and lowering ammonia build-up, co-digestion resolves these problems and increase biogas yield. ⁷⁸ Co-digestion reduces methanogenic bacteria inhibition and boosts biogas production by stabilizing substrate pH and diluting toxic chemicals ⁷³ . For instance, co-digesting waste activated sludge with municipal solid waste organic fraction gave up to 500 mL-biogas/g-VS, a significant improvement from mono-digesting which yielded 120–150 mL-biogas/g-VS. ⁷⁶ In addition to raising the total biogas yield, synergistic impact improves process stability and lowers the possibility of system instabilities brought on by the digestion of a single substrate type. ⁷³ Mango waste is considered one of the promising feedstocks for biogas production due to its high organic content and widespread availability in mango-producing regions. ⁷⁹ Mango wastes such as peels, seeds, and pulp are rich in carbohydrates, fibres, and other organic compounds, making them ideal feedstock for anaerobic digestion a biological process that produces biogas, a renewable energy source primarily composed of methane (CH₄) and carbon dioxide (CO₂). ⁸⁰ The anaerobic co-digestion process is accelerated and enhanced by the presence of rumen bacteria, which are often abundant in manure such as cow dung and sheep manure. ¹¹ Therefore, mango wastes can be effectively co-digested with manure, allowing for improved biogas production and enhanced waste management through the combined anaerobic digestion of both organic materials. Utilizing mango waste not only helps in managing agro-industrial by-products sustainably but also enhances the efficiency of anaerobic digestion, contributing to increased biogas yield and reduced environmental pollution. Studies indicate the generation of biogas from mango waste co-digested with seed kernel yielded biogas with 74%,^80,81 a mixture of mango waste and pig manure yielded 64% biogas, compared to 54% when pig manure was digested alone. Similarly, biogas production increased significantly from 28% to 55% when rabbit dung was co-digested with mango waste. ⁸²

Mango waste, which includes peels, seeds, and fibrous pulp residues, has been studied as a potential substrate to produce biodiesel, bioethanol, and biogas. Its high carbohydrate, lipid, and lignocellulosic content makes it suitable for biofuel generation, but the yields vary compared with other commonly used substrates as presented in Table 1. ³² Table 1 compares the viability of using mango waste for biodiesel, bioethanol, and biogas production against food sources substrates. While mango seed oil's yield is lower than that of soybean and palm, it remains viable in areas rich in mango waste due to its low cost. ⁸³ Bioethanol produced from mango peel and pulp, show moderate yields compared to sugarcane and corn but is advantageous in mango-producing regions. ³² For biogas, methane yields from mango waste are comparable to cattle manure, indicating its potential, especially with co-digestion. ⁸⁴ Overall, although mango waste does not exceed conventional substrates in yield, its availability and waste management benefits make it a promising option for localized biofuel production systems.

Table 1.

Biofuel yields from mango waste and other substrates.

Biofuel type	Mango waste substrate	Common alternative substrates	Comparative feasibility
Biodiesel	Mango seed oil: ∼8%–12% oil yield (w/w basis)	Soybean: ∼18%–20% oil; Palm: ∼30%–35% oil	Lower yield, but feasible where mango waste is abundant
Bioethanol	Mango peel/pulp hydrolysate: ∼20–30 g/L ethanol	Sugarcane juice: ∼80–100 g/L; Corn starch: ∼40–60 g/L	Moderate yields; good alternative in mango-producing areas
Biogas	Mango waste anaerobic digestion: ∼300–400 mL CH₄/g VS	Food waste: ∼400–600 mL CH₄/g VS; Cattle manure: ∼200–300 mL CH₄/g VS	Comparable to manure; slightly lower than food waste, still viable

Future Outlook on Biofuel Production from mango Waste

Mango wastes including peels, seeds, and pulp leftovers can be used to produce bioethanol, biodiesel, and biogas sustainably, offering a sustainable and profitable solution to manage waste and produce renewable energy, contributing to global energy mix. From this perspective, mango is a promising feedstock for biofuels generation. Optimising conversion processes to maximise yield and efficiency is crucial to future advancements in the use of mango waste for biofuel production. The production of bioethanol using mango as feedstock could be greatly increased by using genetically modified yeast strains, improving enzymatic hydrolysis processes and through using additional fermentable sugars sources such as millet and sorghum. Lipid extraction from mango seed oil may be enhanced for biodiesel generation with the use of innovative catalysts and eco-friendly transesterification techniques. Creation of strong microbial consortia to increase methane yields and co-digestion techniques with other organic materials are anticipated to boost biogas generation. Furthermore, incorporating mango waste into bio refinery systems presents encouraging opportunities since it permits the concurrent production of several biofuels and high-value by-products including compost, animal feed, and platform chemicals, enhancing overall economic viability. It is critical to address the issues of commercialisation and scalability of biogas production from mango wastes. This entails creating decentralised processing facilities in mango-producing areas, ensuring a steady supply of mango trash, and streamlining logistics for delivery. Commercial adoption of biofuel technology derived from mango waste might be greatly accelerated by strategic partnerships between the public and private sectors, supported by advantageous regulations and incentives. Future research and development initiatives should greatly advance this field as concerns about the depletion of fossil fuel grow and the need for clean energy develop globally.

The findings on biofuel production from mango wastes underscore the need for optimized processes to enhance conversion efficiencies for bioethanol and biogas, focusing on pre-treatment, enzyme formulations, and fermentation conditions. This advocates a shift towards integrated bio-refinery concepts, combining multiple biofuel outputs to maximize energy recovery and improve the energy mix. The variability of mango waste necessitates research into feedstock stabilization and co-digestion and fermentation strategies. Additionally, studies on detoxification, nutrient supplementation, and microbial strain improvements are crucial for enhancing process robustness. Finally, research on techno-economic analyses and life cycle assessments to facilitate the scalability, sustainable production of biofuels from mango waste is suggested.

Limitation of mango Wastes in Biofuel Production

Production of biofuel from mango wastes provides the best alternative energy source to fossil fuel, however bioethanol production from mango wastes have some challenges including seasonal availability of mango fruits, resulting to seasonal supply of raw materials for biofuel production. ⁸⁵ Besides, mango wastes storage is challenging because mango contain high water content (70-85%) thus, its spoilage is rapid. ⁸⁶ Still, mango wastes contain high level of carbon and low level of nitrogen which limit better yeast growth and hinder fermentation. ⁸⁷ The presence of fermentation inhibitors like polyphenols, tannins, and organic acids, may hinder enzymatic activity, lower yeast performance, and eventually bioethanol production. ⁸⁸

Conclusion

Considering increasingly stringent waste management regulations and the pressing need for sustainable energy solutions, the agricultural sector must adopt innovative approaches that balance economic viability with environmental stewardship. The valorization of mango waste into biofuels, including bioethanol, biodiesel, and biogas, emerges as a promising strategy that not only mitigates waste disposal challenges but also generates renewable energy. This multi energy recovery from mango wastes, reduces the environmental problems associated with poor waste disposal, supports waste management policy and circular economy. By harnessing the carbohydrate-rich peels and pulp for bioethanol production, utilizing mango seed oil as a non-food feedstock for biodiesel, and leveraging anaerobic digestion for biogas generation, this approach offers a holistic solution that maximizes energy recovery while minimizing environmental impacts. Moreover, co-digestion with nitrogen-rich substrates can enhance biogas production, underscoring the potential for optimized waste-to-energy conversion. As research continues to refine these pathways, future studies should prioritize assessing the economic feasibility of these processes under local conditions, conducting thorough physicochemical analyses of substrates, and evaluating biodegradability. Additionally, policy frameworks should be taken into account, as they play a crucial role in shaping the implementation of the proposed approach across different mango-producing regions. Addressing these aspects will be critical to enabling the mango industry to transition toward a circular bioeconomy, reduce dependence on fossil fuels, and fully exploit the renewable energy potential of its waste streams.