Stability and antibacterial activity of Thymus daenensis L. essential oil nanoemulsion in mayonnaise

Abstract

BACKGROUND There is a growing demand in the food industry for the replacement of synthetic preservatives with their natural alternatives. This has led to the development of novel methods such as encapsulation of plants essential oil with appropriate physicochemical stability, and antibacterial and organoleptic properties. This study aimed to prepare an optimal nanoemulsion of Thymus daenensis L. essential oil for use as a natural preservative in mayonnaise. RESULTS The analysis of droplet diameter, polydispersity index, zeta potential, encapsulation rate, and intrinsic stability showed that out of nine T. daenensis essential oil‐containing nanoemulsions, two preparations of A and B had high stability scores. In vitro antibacterial tests showed the adverse effect of Tween 80 volume on the antibacterial properties of nanoemulsions. One nanoemulsion (essential oil:Tween 80, ratio 1:1, 15 min sonication) was considered to be optimal based on its long‐term stability and antibacterial effects on Salmonella Typhimurium, Escherichia coli, and Listeria monocytogenes. However, compared to the optimal nanoemulsion, the pure essential oil showed more antibacterial effects. The bacterial control in mayonnaise was close to equal for sodium benzoate (in maximum limit 1 g kg−1) and the optimal nanoemulsion (½ MIC) for 24 h. The optimal nanoemulsion achieved significantly higher sensory scores (taste, appearance, and mouthfeel) than the pure essential oil in mayonnaise (P < 0.05). CONCLUSION The results demonstrated similar antibacterial effects for the optimal nanoemulsion and sodium benzoate. The optimal nanoemulsion, due to its desirable sensorial attributes, long‐term stability, and slow release of volatile compounds, can be considered an appropriate alternative to synthetic preservatives.

Fabrication of nano‐encapsulated angelica (Heracleum persicum) essential oil for enriching dairy dessert: Physicochemical, rheological and sensorial properties

“…Also, the samples containing pure essential oil in both times of the test (first day and 30th day) and especially on the first day due to the sudden release of essential oil volatile substances, caused an unpleasant taste in the product and significantly reduced the sensory evaluation scores. Regarding the effect of nanoemulsions containing plant essential oils on the sensory properties of food products, it can be referred to the research of Mansouri et al [33] which investigated the stability and antibacterial activity of Thymus daenensis L. essential oil nanoemulsion in mayonnaise. Their optimal nanoemulsion achieved significantly higher sensory scores (taste, appearance, and mouthfeel) than the pure essential oil in mayonnaise.…”

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