Holy Peel: Underrated waste that can save the environment

Elena Vardanian
09.11.2021
4 min read

Increased consumption of vegetables and fruits brings tonnes of benefits — from saving health to reducing medical costs. But large amounts of peel waste from fruit and vegetable-based industries and household kitchens turn the wheel of benefits backwards and already lead to a big nutritional and economic loss and environmental problems. However, we can undo the damage by producing eco-friendly and sustainable value-added products.

Tops and tails

According to the United Nations Food and Agriculture Organization at least one-third of the food produced in the world (estimated as 1.3 billion metric tons) is lost and wasted every year. Losses and waste of horticultural commodities are the highest among all types of foods, reaching up to 60%! Many fruits and vegetables generate at least up to 25% to 30% of waste materials, which are not further used. For example, processing of mangoes produces about 11% of peels, 13.5% of seeds, 18% of inoperable pulp, and only 58% of finished product. (1)

Fruit and vegetable waste (FVW) is composed mainly of roots, seeds, peels, rinds, and pomace. Quantity and type of FVWs vary from commodity to commodity, but peel waste is something that is more often left after producing fruits (papaya — 8.5% of peels, pinapple — 14% of peels), citrus fruits (mandarin — 16% of peels) and vegetables (potato — 15% of peels). (1)

Peel contains good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils. For instance, peel of mango and orange contain more than 50% of total dietary fibers. Bioactive compounds extracted from FVWs can be used in cosmetics, food, textile and pharmaceutical industries to promote a sustainable approach to food wastes and solve the environmental issues.

In peeling we trust

Peel-Based Edible Films/Coating
Many phenolic substances with excellent antioxidant capacity make fruits and vegetable peels suitable materials for inclusion into films and coatings. Microencapsulated edible film or coating with essential oils along with antimicrobial agents effectively enhances the safety and quality of cereals and food products. For instance, gelatin coating combined with orange peel essential oil preserved shrimp quality during cold storage with a shelf-life extension of about 6 days. (2)
Fruit Peel Fortified Probiotics
Fruit peel can increase biological activities of probiotics. Did you know that probiotic yogurt prepared with pineapple peel powder can improve the anticancer, antioxidant and antibacterial activities against Escherichia coli?

The addition of apple, banana and passion fruit peel powder in probiotic yogurt also improved the rheological properties and enhanced the growth of Lactobacillus casei, Bifidobacterium animalis subsp. lactis, Lactobacillus acidophilus and Lactobacillus paracasei. (2)
Biochar
Biochar, a stable carbon-rich solid, is generally used to remove different types of pollutant containing heavy metals from contaminated water bodies and also serves as an intermediate for producing bioethanol from biological waste collected from food processing industries.

Different types of food waste have been used for the production of biochar and fruits and vegetables peel wastes are among them. In particular, biochar derived from pineapple, sweet lime and pomelo peel was developed to remove hexavalent chromium from aqueous solution. Biochar derived from litchi peels was used to remove congo red, methyl orange and malachite green from wastewater. Vegetables peel such as garlic, and cucumber are perfect bioadsorbents that remove methylene blue dye from the aqueous solution. (2)
Fruit and Vegetable Peel-Based Microbiological Media
Fruits and vegetable peels are low-cost alternatives to a commercially available media such as Cetrimide agar, Nutrient agar and MacConkey agar. Some fruits and vegetables, such as cabbage, carrot, gooseberry, tomato, pumpkin etc., have been used as a substitute for nutrient agar to culture bacteria and fungi. Dragon fruit and watermelon peel wastes are now used for the production of low-cost growth media for microorganisms and banana peel appears to be an economically low and effective medium for the growth of fungi. (2)