Inhibitory effect of green coffee extracts on Rhizopus stolonifer: in-silico and in-situ evidence

Abstract

This study investigated the antimicrobial efficacy of Coffea arabica green bean extracts (methanol and ethanol) against six pathogens: Proteus mirabilis, Shigella flexneri, Staphylococcus aureus, Penicillium digitatum, Rhizopus stolonifer, and Aspergillus niger. Ethanol extract demonstrated significantly superior activity (p < 0.05) over methanol and controls, despite fewer compounds, attributed to higher concentrations of key bioactives identified via HPLC and GC–MS. Molecular docking identified hesperidin, diosmin, naringin, and rutin as key compounds responsible for antibacterial and antifungal activity, targeting topoisomerase ATPase and AmFPI-1 fungal protease, respectively. In-situ analysis showed that white wheat bread with ≥ 5% green coffee powder inhibited Rhizopus stolonifer growth for seven days at 30 °C, similar to the propionic acid effect. However, 10% green coffee negatively impacted the sensory attributes of bread samples, especially color and taste. This suggests green coffee is a potential natural preservative to extend the shelf life of bread while considering cost and consumer acceptability.