Optimization of ultrasound-assisted microemulsions of citral using biopolymers: characterization and antifungal activity

Abstract

Citral is an essential oil with antimicrobial activity against a broad range of microorganisms. However, its low solubility and susceptibility to environmental conditions difficult the use of citral in the food industry. In this study, the formulation of an eco-friendly emulsion of citral obtained by ultrasound was optimized using a Box-Behnken design. The effect of arabic gum (AG), sodium alginate (SA), maltodextrin (MD), and their concentration on the droplet size of the emulsion was evaluated. Based on the droplet size (1 μm), the emulsion formulated using 7.5% of AG and 0.4% of SA was selected as optimal with viscosity 34.63 cP, pH 5.76, and conductivity 1.426 mS. This emulsion retains the 92% volatile fraction of citral and contributes to increase the thermal stability of the essential oil from 37 to 185 °C. Besides, it has antifungal properties against Fusarium sp., contributing to reduce in 66% of the disease incidence caused by this fungus in bananas. Therefore, the optimal emulsion formulated in this research can be used to control the postharvest decay in fruits. Moreover, it can be used to obtain microcapsules and microfibers that can be used as edible coatings in the food industry.

Graphical Abstract

Keywords:

• Emulsion
• thermal analyses
• Arabic gum
• sodium alginate
• maltodextrin
• Fusarium sp

Additional information

Funding

The author’s thanks to Tecnológico Nacional de México (Project “Evaluación antifungica de micro y nano estructuras adicionadas con antimicrobianos naturales”, code 8209.20-P) for their support in conducting the work throughout this project, CYTED thematic network code 319RT0576, CONACYT to the grants awarded to Dulce María Miss-Zacarías [Grant number 701301] and Maricarmen Iñiguez-Moreno [Grant number 740456], and MSc. Julio Cesar Barros-Castillo for technical assistance.