keywords: Antimicrobial activity, Hibiscus sabdariffa, calyces extracts, inhibitory effect, preservatives
Antimicrobial activity of hibiscus calyces extract was carried out on isolates of bacteria obtained from “kunu” and bread samples determine the inhibitory effect of the hibiscus calyces extracts on the bacteria isolates from the food samples. The hibiscus calyces were extracted with water and ethanol at concentrations of 0.1, 0.15 and 0.20 g/ml, respectively. The following species of bacteria were identified from the food samples of bread and kunu; Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Micrococcus species The antimicrobial activity of H. sabdariffa calyces extract at three different concentrations (0.1, 0.15 and 0.20 g/ml) were tested against the bacteria isolated from the food samples using agar well diffusion method. The aqueous extracts at concentrations of 0.1, 0.15 and 0.20 g/ml did not show any antimicrobial growth effect on all the test microorganisms. At 0.10 g/ml, the ethanolic extracts showed similar results to that of the aqueous extract. At 0.15 g/ml, the antimicrobial effectiveness varied slightly among test organisms. The ethanolic extract at 0.20 g/ml concentration showed the highest potency on all the test microorganisms. Ethanolic extracts of the calyces had a notably higher antibacterial activity on all the test organisms than the aqueous extracts which showed no microbial inhibitory effects at the selected concentrations. The results obtained from this study therefore showed that Hibiscus sabdariffa calyces ethanolic extract at 0.20 g/ml concentration can be used as a non-synthetic food preservatives.