Nutritional and Antioxidant Potential of the Wastes from Three Varieties of Allium Consumed in Côte d’ivoire

Aims: This study aims to evaluate the nutritional and antioxidant potential of the waste products of three varieties of the Allium genus (purple onion, yellow onion and garlic) consumed in Côte d'Ivoire. Place and Duration of Study: This study was conducted at the Biocatalysis and Bioprocesses Laboratory of the Food Science and Technology Training and Research Unit at Nangui ABROGOUA University, Abidjan, Côte d'Ivoire, between September 2024 and June 2025. Methodology: The physicochemical composition of onion (purple and yellow) and garlic waste was determined using standard and referenced methods. Similarly, the total polyphenol, flavonoid, and tannin content, as well as the antioxidant activity, of aqueous and hydroethanolic extracts of this waste were determined. Results: Biochemical analyses reveal that these residues are rich in dietary fiber (27.41–44.03%) and minerals (7.15–8.42%) and have a low energy value (128.96–165.13 kcal/100 g). Hydro-ethanolic extracts show high concentrations of total polyphenols (12.89–45.51 mg Eq AG/g), flavonoids (30.48–106.74 mg Eq Q/g) and tannins (5.23–12.90 mg Eq cat/g). High antioxidant activity was also observed, with antiradical activity indices (IAA) ranging from 0.070 to 26.125 and reducing power values (FRAP) ranging from 28.89 to 37.49 mg Trolox/g. Conclusion: These results highlight the strong potential for valorizing Allium waste as a source of high value-added bioactive compounds. Their exploitation, through sustainable extraction processes, could contribute to better management of agri-food waste and the development of functional ingredients for the agri-food and pharmaceutical industries.