Oil-in-water emulsions of geraniol and carvacrol improve the antibacterial activity of these compounds on raw goat meat surface during extended storage at 4 °C

Abstract

Application of plant-based essential oils as antimicrobial agents has received considerable attention. However, these antimicrobial compounds undergo quick depletion due to various factors such as volatile nature, low-water solubility, and interactions with lipophilic food components. Therefore, to retain the antimicrobial efficacy of such compounds, the combination with an oil-in-water based emulsion system as a carrier can be a viable option. The current work focuses on the development of geraniol and carvacrol loaded oil-in-water emulsion-based coating solutions through ultrasonication approach. Medium chain triglyceride was used as the carrier oil, whereas Tween 80 and gum arabic were used as emulsifiers. The essential oils, geraniol, and carvacrol at ratios of 1:0, 2:1, 1:1, 1:2, and 0:1 (2.5% v/v) were used for the preparation of oil only, non-emulsion formulations and emulsion-based coating solutions, respectively. The emulsion-based coating solutions were characterized for mean particle diameter, polydispersity index, and ζ-potential. These coating solutions were also characterized for microstructural features using confocal laser scanning microscopy and transmission electron microscopy. Finally, the impact of the delivery system on antimicrobial evaporation of oil-only, non-emulsion formulation and emulsion-based coating solutions were assessed against Bacillus cereus MTCC 430 and Escherichia coli MTCC 443. The study showed that the emulsion-entrapped formulations could prolong the antimicrobial efficacy of geraniol and carvacrol till 9 day as compared to treatments performed with oil only, non-emulsion formulations on a goat meat model. Tween-80 and gum arabic stabilized emulsions could be used to extend antimicrobial efficacy of essential oils on solid food matrices.