Antimicrobial Activity of Coffea liberica (Liberian Coffee) in Different Roasting Intensities and Varying Extract Concentrations against Staphylococcus aureus and Escherichia coli

Abstract

Much prior research has shown that coffee, particularly its polyphenolic compounds like caffeine, chlorogenic acid, and melanoidins, exhibits antimicrobial properties against various pathogens. Building on this foundation, this study aimed to determine the antimicrobial activity of Coffea liberica (Liberian Coffee) with a focus on varying roasting intensities and concentrations. Specifically, it investigated the effects of different roasting intensities and extract concentrations against Staphylococcus aureus and Escherichia coli. Coffea liberica contains polyphenols such as caffeine, chlorogenic acid, and melanoidins, known for their antimicrobial properties. The coffee beans were obtained from Amadeo Artisano Coffee Farm and roasted to light and dark intensities. Aqueous extracts were prepared at concentrations of 25%, 50%, 75%, and 100% for each roast intensity using distilled water as the solvent. Cefepime served as a positive control, and distilled water as a negative control. The disc diffusion method on Mueller-Hinton agar plates was used to evaluate the extracts' antimicrobial activity. Results showed that Coffea liberica extracts exhibited no significant antimicrobial activity against Staphylococcus aureus or Escherichia coli across all roasting intensities and concentrations, with inhibition zones equivalent to the negative control. Descriptive statistical analysis confirmed no significant interaction between roasting intensity, extract concentration, and antimicrobial activity. The findings suggest the need for further research using alternative extraction methods, higher concentrations, or different bacteria to fully understand Coffea liberica's potential as a natural antimicrobial agent.