3.3. Coffee extracts from Group 1
In Group 1 regular coffee samples of different species (C. arabica
cv. Yellow Bourbon and C. canephora cv. Conillon) were tested before and after 6, 7, 8, 13 and 15 min of roasting. Both species inhibited S. mutans growth when roasted for 6, 7 and 8 min, with MIC of 5.0 mg/mL. The extracts obtained from green beans and at 13 and 15 min of roasting did not show inhibitory activity at tested concentrations.Inoculation of positive tubes onto a blood agar plate showed that at tested concentrations (5 and 10 mg/mL), the lighter the roasting degree the higher was the inhibitory activity (Table 4).Daglia et al. (1998) observed higher antibacterial activity in acidic
fractions of coffee extracts. In our study, samples showing higher
inhibitory activity (lighter samples) also showed lower pH compared
to darker samples (Table 1).