Improving the Antimicrobial and Antioxidant Activity of Clove (Syzigium aromaticum L.) Essential Oil by Microencapsulation

Abstract

This study aimed to investigate the effect of microencapsulation on the bioactive properties of clove essential oil (CEO). The CEO was microencapsulated into various wall materials, including maltodextrin (MD) and sodium caseinate (SC), and their combination with gum arabic (GA) and gelatin (G), through freeze-drying. The effects of wall material blend (MD-SC, MD-SC-GA, and MD-SC-G) on microencapsulation efficiency, morphology, in vitro release profile, antioxidant and antimicrobial properties were investigated. The MD-SC blend offered the best microencapsulation properties in terms of encapsulation efficiency (86.22%), ideal microcapsule shape, and maximum release rate (85.98%). Microencapsulation extended the radical scavenging time of the CEO. DPPH and ABTS scavenging activities of MD-SC microencapsulated CEO were 83.61% and 82.96% inhibition, while values were 76.37% and 80.03% inhibition for free CEO, respectively. Antimicrobial activities of microencapsulated and free CEO were investigated against eight microorganisms with in vitro (broth microdilution technique) and in-situ tests. Both free and CEO-loaded microcapsules were able to inhibit the growth of Gram-positive bacteria, except for Bacillus cereus, at the same concentration. Microencapsulated CEO exhibited weaker antimicrobial activity on Gram-negative bacteria than free CEO. The influence of the pH of fruit juices and components of milk on the antimicrobial activity of microencapsulated CEO was also evaluated. Microencapsulated CEO may have different antimicrobial effects depending on the pH and content of the food. This study showed that microencapsulation of CEO increased the application dose for antimicrobial effect in foods.