Effects of chemical ripening with calcium carbide on nutritional composition, antioxidant capacity and heavy metal accumulation in climacteric fruits

Fruits are important dietary sources of nutrients, phytochemicals and antioxidants essential for human health. In many developing countries, calcium carbide (CaC₂) is widely used as a low-cost artificial ripening agent despite its associated health risks. This study evaluated the impact of CaC₂ ripening on the nutritional composition, phytochemical content, antioxidant properties and elemental profile of banana (Musa spp.), mango (Mangifera indica) and plantain (Musa paradisiaca). Fruits were naturally ripened (control) or treated with 10 or 30 g/kg CaC₂. Standard analytical methods were used to determine proximate composition, phytochemicals, antioxidant activity (DPPH, FRAP and TPC), vitamins, mineral elements and heavy metals. CaC₂ treatment significantly increased ash content while reducing protein, carbohydrate and lipid levels, with fibre responses varying among fruits. Phytochemical profiles were altered in a dose-dependent and fruit-specific manner, including reductions in alkaloids and polyphenols and increases in flavonoids and tannins. Antioxidant vitamins (C and E) decreased significantly (p < 0.05), and antioxidant activities were generally suppressed, particularly DPPH radical scavenging capacity. Mineral concentrations increased due to contributions from CaC₂, while toxic heavy metals (arsenic, lead and cadmium) were present in CaC₂ and accumulated significantly in treated fruits, with arsenic showing the greatest increase. Collectively, these changes indicate that CaC₂ not only accelerates ripening but may also promote progression toward overripening, leading to nutrient depletion and biochemical deterioration. This study provides an integrated, multiparameter evaluation of CaC_2-induced ripening across multiple climacteric fruits and demonstrates direct transfer of toxic contaminants into edible tissues. The findings highlight significant food safety concerns and underscore the need for stricter regulation, control and the promotion of safer, sustainable ripening alternatives.