Comparative studies on the antimicrobial activity of black pepper (piper nigrum) and turmeric (curcuma longa) extracts.

ABSTRACT

In the present study, a total of six extracts of two spices namely black pepper and turmeric in three solvents were evaluated for their antibacterial and antifungal activity. The antibacterial activity was measured by agar well diffusion method and antifungal activity by poisoned food technique. All the extracts showed antibacterial activity against all the test bacterial isolates. Aqueous extracts of black pepper did not exhibit antibacterial activity against B. subtilis. In aqueous extract, black pepper and turmeric showed good inhibitory activity against Staphylococcus aureus with zone of inhibition 25mm to 30mm and 26mm to 28mm respectively. In ethanolic extract, black pepper extract showed antibacterial activity against all test bacteria with zone of inhibition ranged between 15mm and 22mm while turmeric showed activity with zone of inhibition ranged between 13mm and 24mm. In methanolic extract, the diameter of zone of inhibition ranged between 12mm and 28mm in black pepper and 13mm and 22mm in turmeric. In case of antifungal activity, only turmeric ethanolic extract showed activity only against Rhizopus stolonifer and Mucor sp. with percent mycelial growth inhibition ranged between 25% and 30%. Based on this finding, these extracts may be an alternative to chemical preservatives and used as natural antimicrobial preservatives to reclaim the shelf-life of food.