Physicochemical Profiles and Antimicrobial Activity of Ozonated Palm Kernel Oil

Abstract

ABSTRACT Palm kernel oil (PKO) is a vegetable oil containing active substances beneficial for medicine and health. The applications of PKO can be extended by synthesizing ozonated PKO (OPKO). In this study, the PKO was ozonated at different intervals (0, 1, 3, 7, and 24 h). The physicochemical properties of OPKO were studied, including iodine value (IV), peroxide value (PV), acid value (AV), anisidine value (p-AV), viscosity and fatty acid composition (FAC). Meanwhile, the spectroscopic characteristics, melting and crystallization properties of OPKO were also investigated. Besides, the present study also examined the antimicrobial properties of OPKO against Gram-positive and Gram-negative bacteria as well as fungi using agar disk-diffusion method. The results showed that PV, AV, and viscosity of the OPKO increased in parallel with increasing ozonation time, reaching 963.6 ± 25.0 meq O2/kg fat, 45.30 ± 1.45 mg KOH/g oil, and 196.3 ± 1.6 mPa.s, respectively, after 24 h of ozonation. On the other hand, prolonged ozonation time reduced oleic acid and led to lower IV of 1.6 ± 0.7 g I2/100 g oil. The p-AV exhibited an increasing-decreasing trend, reaching a peak at 3 h ozonation period. Spectroscopic analysis showed that the absorption band at 1712 cm−1, 1400 cm−1, and 1112 cm−1, attributed to C=O, O-H, and -C-O, respectively, were altered with the ozonation time, indicating the change in the chemical composition of PKO. Moreover, the change in the FAC also affected the crystallization and melting profiles of PKO. This work also demonstrated the excellent antimicrobial properties of OPKO with significant inhibition effects against several types of microorganisms tested. Therefore, OPKO can be an essential component with great potential for cosmetics and pharmaceutical products.