Extraction and antibacterial activity of essential oil from cloves (Syzygium aromaticum)

Recently, there has been rising concern on using synthetic antibacterial agents in food preservation. This led to growing interest in finding natural food additives with a broad spectrum of antibacterial activity to replace those synthetic chemical additives. Essential oils have been shown to possess antibacterial activities, thus present a great potential as natural antibacterial agents. In this study, essential oil was extracted from dried clove buds (Syzygium aromaticum) using steam distillation. The effect of different grinding methods and distillation times on essential oil yield was investigated. The antibacterial activity of clove oil was evaluated using disc diffusion and broth dilution method. The presence of eugenol in clove oil was validated using high performance liquid chromatography (HPLC). The highest essential oil yield was obtained using dried clove buds ground with mortar and pestle at 5 hours distillation time. Clove oil showed highest inhibitory effect against Bacillus subtilis ATCC 6633, followed by Salmonella typhimurium ATCC 14028, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Essential oil extracted for 7 hours from dried clove buds ground with mortar and pestle showed the highest antibacterial activity. Results of HPLC analysis validated that eugenol was found in clove oil. The present study showed that clove oil has a great potential as natural antibacterial agent in the food preservation system as it exhibited a broad spectrum of antibacterial activity against both Gram-positive and Gram-negative bacteria.