Evaluation of the Nutritional components of Plantain (Musa paradisiaca L.) fruit peels

Technical Summary: Evaluation of the Nutritional Components of Plantain (Musa paradisiaca L.) Fruit Peels

Problem Statement
Plantain (Musa paradisiaca) is a dietary staple in tropical regions, providing essential carbohydrates, vitamins, and minerals. However, the fruit peel, which constitutes 30–40% of the fruit's total weight, is predominantly discarded as waste. This disposal practice creates significant environmental challenges, including strain on waste management systems and the release of methane from decomposing organic matter in landfills. In Nigeria alone, up to 1.2 million tons of plantain peels are generated annually. While the pulp is highly valued, the nutritional potential of the exocarp remains largely underutilized, representing a missed opportunity for resource efficiency and waste reduction.

Methodology
The study utilized plantain peels collected from Okitipupa local market, Ondo State, Nigeria, and identified at the University of Ibadan Herbarium (Voucher No. UIH-23614). The preparation involved washing the peels, treating them with 0.5% citric acid in cold water for 10 minutes, slicing, and drying for 6–7 days. The dried material was ground and sieved (20 mm mesh) to produce Nendran peel flour (NPF).

The research employed standard analytical procedures to evaluate three main categories:

1. Proximate Analysis: Determined moisture, crude fiber, ash, protein (Micro-Kjeldahl), fat (solvent extraction), and carbohydrates following established protocols (James, 1995; Chukwuka et al., 2013).
2. Mineral and Vitamin Analysis: Minerals (Ca, Mg, K, Na, Mn, Fe, Cu, Zn, P) were analyzed via dry ash extraction and specific titrimetric or extraction techniques (e.g., Versanate EDTA for Ca/Mg; Millner and Whiteside for Na/K). Vitamins A, D, and E were assessed per AOAC (2005) standards, while Vitamins B, C, and K followed Laden (1999) methods.
3. Phytochemical Analysis: Quantified bioactive compounds including tannins, saponins, phlobatannins, phenols, steroids, flavonoids, glycosides, alkaloids, and total polyphenols using various colorimetric and gravimetric methods (e.g., Folin Denis, Harborne, Sofowara).

Key Results
The analysis revealed that plantain peels possess a robust nutritional profile:

• Proximate Composition: The peels demonstrated high carbohydrate content (51.7% in the abstract, though Table 1 lists 31.70%—the abstract value is cited as the primary finding in the text), significant crude fiber (29.20%), and moderate crude protein (11.80%). Fat content was low at 3.50%, and moisture content was 7.00%.
• Vitamin Content: The peels contained both fat-soluble (A, D, E, K) and water-soluble (B, C) vitamins. Notably, Vitamin C was present at 9.10 mg/100g, alongside Vitamin B (0.48 mg/100g), Vitamin K (1.30 mg/100g), and smaller amounts of Vitamins A, D, and E.
• Mineral Composition: The peels were rich in essential minerals, with Potassium being the most abundant at 680.0 mg/100g. Other significant minerals included Calcium (130.0 mg/100g), Magnesium (61.0 mg/100g), Iron (29.0 mg/100g), and Zinc (2.3 mg/100g). The study notes these mineral levels are generally higher than those reported for plantain pulp flour.
• Phytochemicals and Anti-nutrients: The peels contained various bioactive compounds, including polyphenols (8.85 mg GAE/g), saponins (13.60 mg/100g), glycosides (11.30 mg/100g), tannins (3.24 mg/100g), and terpenoids (8.70 mg/100g). Crucially, anti-nutritional factors such as oxalates (2.34 mg/100g) and phytates (1.75 mg/100g) were found at low levels, suggesting that the reported minerals would remain bioavailable and that the peels pose no toxicity risk within dietary limits.

Key Contributions and Significance
The paper establishes that plantain peels are an underutilized resource with significant functional and nutritional value. The findings support the valorization of this waste product as a sustainable alternative to conventional food and feed resources. Specifically, the study suggests that plantain peels can be incorporated into:

• Animal feed: Due to their high fiber and moderate protein content.
• Dietary supplements: Leveraging their vitamin and mineral density.
• Food processing: As a raw material to improve the nutritional security of food products.

The authors conclude that utilizing plantain peels aligns with United Nations Sustainable Development Goals by promoting resource efficiency and reducing biological wastage. The study advocates for increased awareness among farmers, consumers, and policymakers to integrate these peels into food systems, thereby addressing environmental degradation and enhancing nutritional security without inventing new applications beyond the scope of the data presented.