Formulation and effectiveness of solid soap preparations from citronella grass (Cymbopogon nardus L.) essential oil extract against Listeria monocytogenes

Background: The components of essential oils, such as citronellol, citronellal, and geraniol, have been reported to possess the ability to inhibit bacteria. Furthermore, Listeria monocytogenes is a bacteria that often affects humans, and its infections can cause meningitis and bacteremia. In pregnant women, Listeria monocytogenes can cause flu-like syndrome with complications of miscarriage, infant death, and meningitis in infants. Objective: This study evaluated the suitability of solid soap preparations from citronella grass essential oil based on its physical properties, such as organoleptic tests, assessments of chemical tests, and the effectiveness of the sample produced against bacteria. Method: The soap-making process was initiated by mixing the fat fraction (stearic acid and coconut oil) with an alkali, namely 30% NaOH. The soap stock was then added to the other ingredients and stirred until it became homogeneous for testing. Results: The test showed a pH value, water content, total fat, ethanol insoluble material, free fatty acids, chloride content, and unsaponificable fat of 10.8, 14.26, 74.84, 2.4, 0.26, 0.48, and 85.8, respectively. Furthermore, the sample showed a high level of inhibition against Listeria monocytogenes. Conclusion: Evaluation of citronella essential oil extract soap met the requirements, except for its unsaponifiable fat.