Improving the stability of thyme essential oil solid liposome by using β-cyclodextrin as a cryoprotectant

Area of Science:

• Food Science
• Microbiology
• Materials Science

Background:

• Escherichia coli O157:H7 poses a significant food safety risk.
• Thyme essential oil (TEO) exhibits antimicrobial properties.
• Liposomes offer a promising delivery system for bioactive compounds.

Purpose of the Study:

• To develop freeze-dried ε-polylysine (ε-PLY)-coated thyme essential oil (TEO) liposomes (SLPs).
• To evaluate the physicochemical properties of SLPs.
• To assess the efficacy of SLPs in controlling Escherichia coli O157:H7 in vegetable juices.

Main Methods:

• Solid liposomes (SLPs) were prepared via freeze-drying with varying β-cyclodextrin: lipid ratios.
• Spectroscopic methods (UV-Vis, FTIR) confirmed TEO and ε-PLY presence.
• Physicochemical properties (morphology, antioxidant activity, digestibility, release rate, phase inversion temperature) were analyzed.
• Antibacterial activity against Escherichia coli O157:H7 in vegetable juices was tested.

Main Results:

• Optimal physical and chemical properties of SLPs were achieved at a β-cyclodextrin: lipid ratio of 6:1.
• SLPs stored at 4°C and 12°C demonstrated favorable particle size, PDI, and zeta potential.
• A concentration of 5 mg/mL of SLPs effectively inhibited Escherichia coli O157:H7 growth in four types of vegetable juices.

Conclusions:

• Freeze-drying with β-cyclodextrin is an effective method for preparing ε-PLY-coated TEO liposomes.
• The developed SLPs exhibit desirable properties for food applications.
• SLPs show significant potential as natural antibacterial agents to enhance the safety of vegetable juices.