Comparative Evaluation of Antimicrobial Effects of Green and Roasted Beans of Coffee Robusta and Coffee Arabica on Streptococcus Mutans – An In Vitro Study

Abstract

Aim:
To comparatively evaluate the antibacterial efficacy of green and roasted Coffee Robusta and Coffee Arabica extracts against Streptococcus mutans.

Methods:
An in vitro experimental study was conducted. Aqueous extracts were prepared by decocting 20 g of finely powdered coffee in 100 mL of distilled water at 100°C for 7 minutes. Extracts were standardized at concentrations of 4 g and 10 g. Antibacterial activity was assessed using the agar well diffusion method on blood agar plates inoculated with Streptococcus mutans. Following 24-hour incubation at 37°C, zones of inhibition were measured in millimeters. Data were analyzed using one-way ANOVA and post-hoc Bonferroni test, with statistical significance set at p < 0.05.

Results:
Statistically significant differences were observed among groups at both concentrations (p < 0.001). Green Robusta exhibited the highest antibacterial activity (16.78 ± 0.47 mm at 4 g; 20.53 ± 0.51 mm at 10 g), followed by chlorhexidine (15.65 ± 0.62 mm; 19.65 ± 0.62 mm). All groups demonstrated a significant concentration-dependent increase in inhibition (p < 0.01). At 10 g concentration,

Conclusion:
Green coffee extracts, particularly Green Robusta, demonstrated significant antibacterial activity against Streptococcus mutans and showed efficacy comparable to chlorhexidine at higher concentration, indicating potential as a natural antimicrobial agent in caries prevention.