Impact of Microbial Inoculants and Fruit Extracts on Cadmium Reduction and Quality Parameters in Cocoa (Theobroma cacao L.): From Beans to Cocoa Paste

Cadmium (Cd) accumulation in cacao (Theobroma cacao L.) beans represents a significant threat to international food safety standards. This study evaluated the efficacy of microbial inoculants (efficient microorganism, EMs) combined with tropical fruit extracts (Musa × paradisiaca, Artocarpus heterophyllus, and Passiflora edulis) on mitigating Cd levels during cocoa fermentation. During fermentation, all treatments exhibited a progressive increase in pH and temperature, alongside a decline in total soluble solids, reflecting intensified microbial metabolic activity. Cd reduction was found to be dose-dependent on EM concentration and fruit extract, and synergistic effects were shown by EM and fruit extracts. The most effective treatment, i.e., 80% EMs + P. edulis extract, reduced 33.5% Cd levels, i.e., from 3.67 mg/kg to 2.44 mg/kg. Additionally, these biotechnological approaches improved post-harvest cocoa quality, with fermentation levels exceeding 95% for well-fermented beans and reducing defective beans to near zero. In conclusion, directed fermentation using EMs and tropical fruit extracts provides a robust strategy for Cd mitigation and qualitative enhancement of cacao beans.