Eugenol Nanoencapsulated by Sodium Caseinate: Physical, Antimicrobial, and Biophysical Properties

Abstract

To improve the application of essential oils as natural antimicrobial preservatives, the objective of the present study was to determine physical, antimicrobial, and biophysical properties of eugenol after nanoencapsulation by sodium caseinate (NaCas). Emulsions were prepared by mixing eugenol in 20.0 mg/mL NaCas solution at an overall eugenol content of 5.0-137.9 mg/mL using shear homogenization. Stable emulsions were observed up to 38.5 mg/mL eugenol, which had droplet diameters of smaller than 125 nm at pH 5-9 after ambient storage for up to 30 days. The encapsulated eugenol had similar minimal inhibitory and minimal bactericidal concentrations as free eugenol against Escherichia coli O157:H7 ATCC 43895, Listeria monocytogenes Scott A, and Salmonella Enteritidis but showed better inhibition of E. coli O157:H7 than free eugenol during incubation at 37 °C for 48 h. After 20 min interaction at 21 °C, bacteria treated with encapsulated eugenol had a greater reduction of intracellular ATP and a greater increase of extracellular ATP than free eugenol, suggesting the enhanced permeation of eugenol after nanoencapsulation. However, such overall trend was not observed when examining bacterial morphology and uptake of crystal violet, suggesting the possible membrane adaptation. Findings from this study showed the feasibility of preparing nanoemulsions with high loading of eugenol using NaCas.

Bio-Based Nanoemulsion Formulations Applicable in Agriculture, Medicine, and Food Industry

“…Optimized ultrasound-mediated nettle oil (1.25 wt%) NEs stabilized by purified jujube polysaccharide with 86.75 nm droplet size inactivated the Gram-positive bacterium more effectively than the Gram-negative one (Gharibzahedi 2017). Stable NEs prepared by mixing eugenol with SCas using shear homogenization observed up to 38.5 mg/mL eugenol showed droplet diameters <125 nm at pH 5−9 after ambient storage for up to 30 days and more effective inhibition of E. coli O157:H7 than free eugenol during incubation at 37 °C for 48 h. A greater reduction of intracellular ATP and a greater increase of extracellular ATP was observed in bacteria treated with encapsulated eugenol (20 min interaction at 21 °C) compared to free eugenol suggesting enhanced permeation of eugenol due to its nanoencapsulation, although the possible membrane adaptation could not be excluded (Zhang et al 2018). Salvia-Trujillo et al (2014) reported that lemongrass oil−alginate NEs prepared by microfluidization exhibited enhanced antimicrobial activity against E. coli, while ultrasound processing of NEs led to loss of their bactericidal action.…”

Spray Drying for the Encapsulation of Oils—A Review

“…Specifically, soy or whey protein with maltodextrins are frequently applied, generally due to the variety of maltodextrins DE [ 74 ]. Among dairy proteins, sodium caseinate is preferred over other proteins due to its high solubility in water, emulsifying properties with oil and rapid formation of interfacial films and excellent surface activity [ 75 ]. Sodium caseinate has been reported to be the most effective emulsion stabilizer for fats.…”

Metal-organic Framework-based Materials: Synthesis, Stability and Applications in Food Safety and Preservation

“…[1][2][3][4][5] Nanotechnologies have promoted the development of food safety and quality. For example, antibacterial essential oil emulsions and films were employed for food sterilization, [6][7][8][9][10][11] high-efficiency preservatives and growth regulators were synthesized through nano-assembly to govern food shelf-life and ripening, [12,13] also, sensitive nanosensors were developed to determine harmful and safety uncertain ingredients in food. [14,15] Porous materials have gradually aroused the interest of scientists because of their unique structure and property, and showed great potential in food applications.…”