Antimicrobial Activities And Preservative Potentials Of Some Plant Extracts In Minced Meat.

ABSTRACT

The antimicrobial activities and preservative potentials of crude plant extracts of stem bark of Alstonia boonei, leaves of Euphorbia hirta and seeds of Moringa oleifera were studied. Soxhlet extraction method and cold ethanol extraction method were used for the extraction of the dried and ground plant samples. The well in agar diffusion method was used for the antibacterial screening at different concentrations of 25mg/ml, 50mg/ml, 100mg/ml and 200mg/ml on Eschericia coli, Bacillus subtilis, Staphylococcus aureus, Salmonella typhi and Saccharomyces cerevisiae. The minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) were also determined. The preservative effects of the crude plant extracts at 0.1%, 0.2% and 0.3% singly and in combination were determined in minced meat using E. coli and B. subtilis as test isolates. Euphorbia hirta cold and Alstonia boonei hot extract gave the highest zone of growth inhibition on E. coli and B.subtilis with 20mm zone diameter at 200mg/ml concentration. There was no significant difference (p≤ 0.05) on the MIC at different concentrations; however, the lowest MIC was 50mg/ml concentration on E.coli, while the highest MIC was 200mg/ml concentration on S. cerevisiae. Significant differences (p≤ 0.05) exist in the MBC values. The lowest MBC value was 50mg/ml on E.coli. Alstonia boonei at 0.1, and 0.2% produced a log cycle reduction on the growth of E.coli. The mixture of the two extracts (50:50) at 0.1% and 0.2% also produced a log cycle reduction on the growth of E.coli; however the A. boonei extracts had more significant effect on the isolates. The results obtained reveal the potentials of plant extracts as natural food preservation in minced meat. Thus the crude plant extracts can act as inhibitors of the bacteria in minced meat.