The world faces a staggering food waste crisis, with 1.3 billion tons of food discarded annually—enough to feed billions of people. Among the overlooked contributors to this problem is pumpkin peel, a by-product often treated as trash.
In 2022 alone, global pumpkin production reached 23 million tons, but up to 16% of each pumpkin—primarily its peel—is thrown away during processing.
This translates to 0.6–3.68 million tons of pumpkin peel waste every year, most of which ends up in landfills. Beyond harming the environment, this waste ignores the peel’s potential to address food insecurity, reduce industrial waste, and create sustainable products.
The Hidden Value of Pumpkin Peel Waste
Food waste is a pressing global challenge, contributing to 8–10% of greenhouse gas emissions. Organic waste like pumpkin peel releases methane in landfills—a gas 25 times more potent than carbon dioxide (CO₂) over a 100-year period.
Methane, a hydrocarbon, traps heat in the atmosphere far more effectively than CO₂, accelerating climate change by intensifying the greenhouse effect.
Pumpkin processing alone generates vast amounts of waste: 2.6–16% of a pumpkin’s weight is peel, depending on the species (Cucurbita moschata, C. maxima, or C. pepo).
This means every ton of processed pumpkin leaves behind 26–160 kg of peel. Discarding this material not only harms the planet but also wastes nutrients that could combat malnutrition. However, scientists are now uncovering the peel’s hidden value, positioning it as a tool to fight food insecurity and environmental degradation.
Pumpkin Peel Nutrition and Health Benefits
Pumpkin peel is far from ordinary waste. Its nutritional profile rivals many superfoods, offering a mix of macronutrients, minerals, and bioactive compounds.
For starters, carbohydrates make up 56–72% of the peel, primarily in the form of dietary fiber (10–34%) and pectin (25%).
Dietary fiber, a type of indigestible carbohydrate, is essential for digestive health, while pectin—a soluble fiber—forms gels in the gut, slowing sugar absorption and supporting blood sugar regulation. The peel also contains 3–15% protein, including all eight essential amino acids like lysine (15.74 mg/100g) and leucine (6.99 mg/100g).
Amino acids are the building blocks of proteins, vital for muscle repair, enzyme production, and immune function. Additionally, the peel’s fat content (2–6%) includes heart-healthy unsaturated fatty acids such as linolenic acid (36.65%) and oleic acid (19.23%), which reduce inflammation and improve cholesterol levels.
When it comes to minerals, pumpkin peel is exceptionally rich in potassium (374–1,212 mg/100g)—higher than spinach (716 mg/100g) and kale (564 mg/100g). Potassium, an electrolyte, regulates fluid balance, nerve signals, and muscle contractions, making it crucial for heart health.
The peel also provides smaller amounts of iron (0.24–5.42 mg/100g) and zinc (0.25–0.74 mg/100g). Iron is necessary for oxygen transport in blood, while zinc supports immune function and wound healing.
The peel’s phytochemical content is equally impressive. Phenolic compounds, such as caffeic acid (7.6 mg/100g) and ferulic acid (3.4 mg/100g), act as antioxidants—molecules that neutralize harmful free radicals, protecting cells from oxidative damage linked to aging and diseases like cancer.
Carotenoids, including beta-carotene, lutein, and zeaxanthin, reach concentrations of up to 97 mg/100g. These fat-soluble pigments are precursors to vitamin A, essential for vision, skin health, and immune function.
Lutein and zeaxanthin, specifically, accumulate in the retina, protecting eyes from blue light and reducing the risk of macular degeneration. Compared to other vegetables, pumpkin peel has double the protein of tomato peel and carotenoid levels rivaling carrots.
Innovative Uses for Pumpkin Peel in Food
Scientists and industries are finding creative ways to repurpose pumpkin peel, transforming it into functional foods, natural colorants, and eco-friendly materials.
For example, adding 2–4% pumpkin peel powder to yogurt boosts its fiber content by 10–34% and enriches it with antioxidants.
A 2024 study found that yogurt with 2% peel received the highest sensory scores for texture and flavor, proving that waste can enhance food quality.
Similarly, replacing 20% of wheat flour with peel flour in biscuits increases protein by 15% and iron by 50%.
Consumers in trials preferred these biscuits for their nutty taste and soft texture, showing that sustainability can align with consumer preferences.
Beyond food, pumpkin peel’s vibrant orange pigments are replacing synthetic dyes. Carotenoid-rich extracts are now used by textile companies to dye silk fabrics, achieving excellent colorfastness—resistance to fading during washing or light exposure.
In the beverage industry, these natural colorants are added to juices and functional drinks, offering a safer alternative to artificial additives like tartrazine (Yellow No. 5), which has been linked to hyperactivity in children.
Pumpkin peel is also paving the way for biodegradable packaging. Researchers have combined peel with defatted pumpkin seeds—seeds stripped of oil—to create films with 1,401 kPa tensile strength, comparable to low-grade plastics.
Tensile strength measures a material’s resistance to breaking under tension, ensuring durability.
- These films decompose within 4–6 weeks under composting conditions, reducing plastic pollution, which accounts for 80% of marine debris.
Another groundbreaking application is in water purification. Pumpkin peel biochar—a porous, carbon-rich material produced by heating peel in low-oxygen conditions—can absorb up to 178.6 mg of lead per gram from wastewater.
Lead, a toxic heavy metal, causes neurological damage in humans, making this a critical solution for industries like mining and battery manufacturing.
The cosmetic industry is tapping into the peel’s potential too. Extracts rich in phenolic compounds have shown a sun protection factor (SPF) of 7.59 at 1 mg/mL concentrations, rivaling low-SPF commercial creams. SPF measures protection against UVB rays, which cause sunburn and skin cancer.
Additionally, these compounds reduce oxidative stress—an imbalance between free radicals and antioxidants—in lab tests, slowing skin aging and offering a natural alternative to synthetic anti-aging products like retinol.
Pumpkin Peel as Natural Food Colorants
Advanced technologies are critical to unlocking pumpkin peel’s full potential. For instance, hot water extraction—a method where peel is boiled in water—yields 3.1% polysaccharides, complex carbohydrates that inhibit blood sugar spikes by 17.09% through α-glucosidase enzyme inhibition.
This enzyme breaks down carbohydrates into glucose, so inhibiting it helps manage diabetes. Microwave-assisted extraction (MAE), which uses electromagnetic waves to heat the peel, is even more efficient, producing 18.05% high-methoxyl pectin in just five minutes.
High-methoxyl pectin, with a degree of esterification above 50%, forms strong gels in acidic conditions, making it ideal for jams and jellies.
Carotenoid extraction has also seen innovations. Ultrasound-assisted extraction (UAE) uses sound waves to rupture plant cells, releasing 33.78–38.03 µg/g of carotenoids—double the yield of conventional methods. UAE avoids toxic solvents like hexane, instead using corn oil as a green solvent, aligning with the 12 Principles of Green Chemistry.
Enzyme-assisted extraction, another emerging method, employs cellulase and pectinase enzymes to break down cell walls, boosting phenolic compound recovery by 40%.
Challenges in Scaling Pumpkin Peel Recycling
Despite its promise, several hurdles hinder widespread adoption of pumpkin peel valorization. Fresh peel spoils within 48 hours due to microbial growth, requiring immediate processing.
- Freeze-drying, a method where peel is frozen and moisture is removed under vacuum, preserves 95% of its nutrients but costs $2–5 per kilogram, making it unaffordable for small-scale farmers.
- Cheaper methods like sun-drying reduce costs but degrade heat-sensitive nutrients like vitamin C.
Consumer acceptance is another challenge. Foods with >20% peel substitution may develop a gritty texture or darker color. For example, bread made with 30% peel flour has a denser crumb and earthy taste, deterring some consumers.
Education campaigns, such as labeling peel-enriched products as “high-fiber” or “antioxidant-rich”, alongside gradual recipe changes, are essential to overcome these barriers.
Scalability is another issue. Most studies are confined to labs, with few real-world applications. Pilot projects, like a 2023 initiative in Bangladesh, are testing peel-based biscuits in school meals to address child malnutrition. Such efforts highlight the need for collaboration between researchers, governments, and industries to scale solutions.
Regulatory gaps also persist. Standards for “upcycled” ingredients—foods made from surplus or by-products—are lacking, though organizations like the Upcycled Food Association are developing certifications to build consumer trust.
Looking ahead, technologies like AI-driven extraction and 3D-printed foods could revolutionize the field. Machine learning models can analyze variables like temperature and solvent type to optimize extraction conditions for maximum yield.
3D printing might turn peel powder into personalized nutrient-dense snacks, catering to dietary needs like gluten-free or high-protein diets. Pharmaceutical applications, such as carotenoid capsules for eye health or phenolic extracts for anti-inflammatory drugs, further expand the peel’s potential.
Pumpkin Peel and Global Sustainability Goals
Pumpkin peel valorization supports multiple United Nations Sustainable Development Goals (SDGs)—a set of 17 objectives to achieve peace and prosperity for people and the planet by 2030. By fortifying staple foods with peel-derived nutrients, it addresses SDG 2 (Zero Hunger), which aims to end malnutrition.
Reducing food waste by 30% through peel reuse aligns with SDG 12 (Responsible Consumption and Production), promoting efficient resource use. Cutting methane emissions from landfills ties into SDG 13 (Climate Action), which focuses on combating climate change.
Industry 5.0—a framework prioritizing human-centric, resilient, and sustainable production—also benefits. Unlike Industry 4.0, which emphasizes automation and data exchange, Industry 5.0 integrates human creativity with advanced technologies.
Small farmers, for instance, can profit by selling peel to food and cosmetic companies, fostering local economies. Decentralized processing units reduce reliance on global supply chains, enhancing resilience against disruptions like pandemics or climate disasters.
Conclusion
Pumpkin peel is no longer a symbol of waste but a beacon of sustainability. Its journey from landfills to labs illustrates how science can transform overlooked resources into tools for global good. By enriching foods, purifying water, and replacing plastics, the peel offers solutions to some of humanity’s most pressing challenges.
As research advances and industries adopt these innovations, pumpkin peel could become a model for circular economies—systems where waste is minimized, and materials are reused indefinitely. The next time you carve a pumpkin, remember: its peel is not just scraps—it’s the foundation of a healthier, greener future.
Power Terms
Sustainable Development Goals (SDGs): The SDGs are 17 global targets set by the United Nations to solve major challenges like poverty, hunger, and climate change by 2030. In the paper, SDG 2 (Zero Hunger) and SDG 12 (Responsible Consumption) are highlighted. Using pumpkin peel reduces food waste and supports these goals by turning waste into useful products like food additives or packaging materials. Example: Reusing pumpkin peel in biscuits aligns with SDG 12 by promoting sustainable food production.
Industry 5.0: This is the fifth phase of industrialization, focusing on human needs, sustainability, and flexible systems. The paper links Industry 5.0 to using pumpkin peel in eco-friendly ways, such as creating biodegradable packaging. Importance: It balances technology with environmental care. Example: Extracting nutrients from pumpkin peel supports Industry 5.0’s goal of reducing industrial waste.
Circular Economy: A system where waste is minimized by reusing materials repeatedly. The paper suggests using pumpkin peel instead of throwing it away. Importance: Reduces landfill waste and saves resources. Example: Pumpkin peel can become biochar to clean wastewater, closing the waste loop.
Food By-products: These are leftovers from food processing, like peels or seeds. Pumpkin peel is a by-product often discarded. Importance: They are rich in nutrients but underused. Use: Pumpkin peel can be added to yogurt or baked goods to boost nutrition.
Upcycling: Transforming waste into higher-value products. Importance: Creates economic opportunities while cutting waste. Example: Pumpkin peel extracts are used in cosmetics as natural antioxidants.
Valorisation: Adding value to waste materials through processing. Importance: Turns trash into useful products. Example: Extracting pectin (a gelling agent) from pumpkin peel for jams or medicines.
Polysaccharides: Long carbohydrate chains, like starch or cellulose. In pumpkin peel, they include pectin and dietary fiber. Importance: Used as thickeners in food or biodegradable materials. Example: Pumpkin peel polysaccharides improve yogurt texture.
Phenolic Compounds: Natural antioxidants in plants that protect cells from damage. Importance: They fight inflammation and diseases. Example: Caffeic acid in pumpkin peel has anti-cancer properties.
Carotenoids: Natural pigments (e.g., beta-carotene) that give plants orange or yellow colors. Importance: They boost eye health and act as natural dyes. Example: Pumpkin peel carotenoids can dye fabrics or enrich foods.
Dietary Fibre: Indigestible plant material that aids digestion. Importance: Lowers cholesterol and regulates blood sugar. Example: Adding pumpkin peel to biscuits increases fiber content.
Pectin: A type of polysaccharide used to thicken jams and jellies. Importance: Pumpkin peel pectin can replace synthetic additives. Example: Extracted pectin is used in biodegradable food packaging.
Proximate Composition: The basic nutritional makeup of a food (e.g., protein, fat, carbs). Importance: Shows the value of pumpkin peel. Example: Pumpkin peel contains 3-15% protein and 56-72% carbohydrates.
Ash Content: Minerals left after burning a sample. Importance: Indicates mineral richness. Example: Pumpkin peel ash (1.8-7.1%) includes potassium and iron.
Fatty Acids: Building blocks of fats. Pumpkin peel oil contains linolenic and palmitic acids. Importance: Essential for energy and cell function. Example: Linolenic acid supports heart health.
Total Phenolic Content (TPC): A measure of antioxidant-rich phenolics in a sample. Importance: Higher TPC means greater health benefits. Example: Pumpkin peel has 67-353 mg GAE (gallic acid equivalent)/100g.
Antioxidant Capacity: Ability to neutralize harmful free radicals. Importance: Prevents diseases like diabetes. Example: Pumpkin peel extracts show high antioxidant activity in lab tests.
Microwave-Assisted Extraction (MAE): Using microwaves to quickly extract compounds. Importance: Saves time and energy. Example: MAE extracts pectin from pumpkin peel in 5 minutes.
Ultrasonic-Assisted Extraction (UAE): Using sound waves to break plant cells and release compounds. Importance: More efficient than traditional methods. Example: UAE extracts more carotenoids from pumpkin peel than solvents.
Conventional Solvent Extraction (CSE): Using chemicals like ethanol to dissolve compounds. Importance: Simple but less eco-friendly. Example: CSE extracts carotenoids but uses harmful solvents.
Biochar-Based Adsorbent: Charcoal made from organic waste to absorb pollutants. Importance: Cleans wastewater sustainably. Example: Pumpkin peel biochar removes dyes and heavy metals.
Natural Colorants: Pigments from plants, not synthetic dyes. Importance: Safer and eco-friendly. Example: Pumpkin peel carotenoids dye silk fabrics yellow-orange.
Sustainable Packaging: Eco-friendly materials that decompose naturally. Importance: Reduces plastic pollution. Example: Films made from pumpkin peel and seeds replace plastic wraps.
Preservation Technology: Methods to keep food or by-products fresh longer. Importance: Prevents spoilage of pumpkin peel. Example: Drying pumpkin peel retains its nutrients for later use.
Green Extraction Technologies: Eco-friendly methods like UAE or MAE. Importance: Reduce chemical use and energy. Example: UAE extracts carotenoids without toxic solvents.
Nutrient Bioavailability: How well the body absorbs nutrients from food. Importance: Determines health benefits. Example: Scientists study how well pumpkin peel minerals are absorbed in humans.
Reference:
Zhang, G., & Liu, L. (2025). Insights into potential value and sustainable utilisation of pumpkin peel: A review. Future Foods, 11, 100575. https://doi.org/10.1016/j.fufo.2025.100575
