Impact of Lemon Grass and Tea Tree Oils on Foodborne Pathogens and their Produced Spoilage Enzymes

ESSENTIAL oils (EOs) are one of antimicrobial agents that naturally found in many plant’s parts and have long been recognized for their medicinal properties. The efficacy of ten essential oils (Tea tree, Lavender, Eucalyptus, Rosemary, Lemon grass, Basil, Olbanum, Cumin, Onion and Cress) against food pathogens isolates and their enzymes have been evaluated. Lemon grass exhibited a potent inhibitory activity against all isolates and Pseudomonas aeruginosa was the most susceptible with MIC and MBC values of 3.12μL/mL and 6.25μL/mL, respectively. Tea tree oil was most effective against fungal isolates, Aspergillus flavus was the most susceptible with MIC value 1.56μL/mL and MFC value 3.12μL/mL. Transmission electron micrographs also confirmed that MIC concentrations of both oils caused many alternations in cell structure of both sensitive bacterial and fungal isolates. The most active antimicrobial fractions of Lemongrass and Tea tree oil were separated using TLC and analyzed by GC-MS as Citral and Terpinen-4-ol, respectively. These compounds exhibited a pronounced inhibitory effect on food spoilage enzymes (amylases, proteases, lactase, and lipases) with inhibition percentages ranged between 80 and 90%.