ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Ultrasonication-assisted formation and characterization of geraniol and carvacrol-loaded emulsions for enhanced antimicrobial activity against food-borne pathogens

Irshaan Syed and Preetam Sarkar

National Institute of Technology Rourkela, Rourkela, India

E-mail: sarkarpreetam@nitrkl.ac.in

Abstract: Gum arabic stabilised oil-in-water emulsions were prepared through ultrasonication approach for the incorporation of natural, plant-based antimicrobial compounds, geraniol and carvacrol. The oil phase of formulated emulsions was constituted with geraniol and carvacrol, incorporated at various ratios of 1:0, 2:1, 1:1, 1:2, and 0:1 (v/v). The ultrasonication procedure was followed using a frequency of 20 kHz at 40% amplitude for 5 min. These emulsion systems were characterized for mean particle diameter, polydispersity index, ζ-potential, storage stability and creaming index. In addition, emulsion microstructure was studied using confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Evaluation of antimicrobial activity of the functional emulsions was carried out against Gram-positive bacteria Bacillus cereus MTCC 430 and Gram-negative bacteria Escherichia coli MTCC 443. The results demonstrated that geraniol: carvacrol (1:1) emulsion formulation displayed good stability with particle size (202.7 ± 4.17 nm), polydispersity (0.282 ± 0.001), ζ-potential (− 19.37 ± 0.06 mV) and no visible separation of cream was observed. Furthermore, the CLSM and TEM observations confirmed the presence of stable emulsion. In addition, the antimicrobial susceptibility tests demonstrated collaborative activity and prolonged antibacterial efficacy for the combined essential oil-based emulsion against both the model bacterial pathogens.

Keywords: Essential oil emulsion ; Geraniol ; Carvacrol ; Food-borne pathogens ; Antimicrobials 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-018-0501-z

Chemical Papers 72 (10) 2659–2672 (2018)