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. 2025 Mar:114:107265.
doi: 10.1016/j.ultsonch.2025.107265. Epub 2025 Feb 9.

Ultrasonic preparation, structural characterization and functional enhancement of thyme essential oil-loaded microcapsules based on mannosylerythritol lipid-A

Shunjie Kang  1 , Qihe Chen  2 , Haorui Ma  1 , Jiwei Ding  1 , Changchun Hao  1 , Qin Shu  3 , Yongfeng Liu  4
Affiliations

Ultrasonic preparation, structural characterization and functional enhancement of thyme essential oil-loaded microcapsules based on mannosylerythritol lipid-A

Shunjie Kang et al. Ultrason Sonochem. 2025 Mar.

Abstract

Mannosylerythritol lipid-A (MEL-A) is a kind of novel biosurfactant and has great potential to apply into food and pharmaceutical field with its outstanding physicochemical and biological property. In this study, Thyme essential oil (TEO) microcapsules based on MEL-A were prepared through ultrasonic emulsification and characterized by size, morphology, structure, antioxidant and antibacterial activity. The results showed the optimal preparation condition was the duration of 15 min and power intensities of 400 W/cm2 through ultrasound treatment, improving the solubility and applicability of TEO. Further experiment explored the physicochemical properties and biological activity of TEO microcapsules, measuring a particle size of 276.19 ± 1.72 nm with good dispersibility. FT-IR, X-ray, and TEM confirmed the successful encapsulation of the essential oil within the microcapsules. Meanwhile, the antioxidant and antibacterial properties of microcapsules were assayed and microcapsules with 7 % MEL-A exhibited better antioxidant properties, while those containing 13 % MEL-A showed better antibacterial performance. In conclusion, MEL-A showed obvious structural stability and functional enhancement in TEO-loaded microcapsules, indicating that its potential applications in food preservation and food machinery sterilization are numerous.

Keywords: Antibacterial activity; Antioxidant activity; Mannosylerythritol lipid-A (MEL-A); Microencapsulation; Thyme essential oil (TEO); Ultrasonic emulsification.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

None
Graphical abstract
Fig. 1
Fig. 1
The chemical structures of the MELs .
Fig. 2
Fig. 2
Particle size, PDI, and potential of MEL-A microcapsules with different concentrations added. Different letters indicate significant differences between each group. (P < 0.05).
Fig. 3
Fig. 3
Particle size of microcapsules with different concentrations of TPP (0.05 %, 0.075 %, 0.1 %) added. Different letters indicate significant differences between each group (P < 0.05).
Fig. 4
Fig. 4
Particle size of microcapsules produced using different ultrasonic power intensity (200, 300, 400 W/cm2). Different letters indicate significant differences between each group (P < 0.05).
Fig. 5
Fig. 5
FTIR of CS, TEO, empty microcapsules, and essential oil-loaded microcapsules.
Fig. 6
Fig. 6
XRD of CS, empty microcapsules, and essential oil loaded microcapsules.
Fig. 7
Fig. 7
TEM images of microcapsules. a. magnification 10,000×; b. magnification 50,000×; c and d. magnification 30,000×.
Fig. 8
Fig. 8
The TGA (a) and DTG (b) curves of microcapsules.
Fig. 9
Fig. 9
Scavenging activity of microcapsules on DPPH radicals (a) and ABTS + radicals (b). Different letters indicate significant differences between each group (P < 0.05).
Fig. 10
Fig. 10
Shows the inhibition rate of microcapsules against S. aureus (a) and E. coli (b) Different letters indicate significant differences between each group (P < 0.05).
Fig. 11
Fig. 11
Inverted fluorescence microscopy images of microcapsules: a. control group (without microcapsule treatment); b. MIC treatment group; c. MBC treatment group.
See this image and copyright information in PMC

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