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Búsquedas previas al 2023, Núm. 3. En la sección Volúmenes 30 - 41 (2012 - 2023).
Antifungal effect of clove essential oil and its main components on fungi isolated from corn tortillas
By Ana Patricia Ibarra Valenzuela, Rosalba Troncoso Rojas, Alma Rosa Islas Rubio, Elizabeth Peralta, Herlinda Soto Valdez*, Hayati Samsudin
* Corresponding Author. Email: / Institution:
Received: 09/April/2024 – Published: 31/December/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2404-4
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Abstract Objective/Background. Corn tortillas are a staple food in México that have a shelf life of 1-2 days at 25 °C due to fungal growth. A natural alternative for controlling fungal growth is clove essential oil (AEC) and its major components: eugenol (E), isoeugenol (I), and eugenyl acetate (AE). Objective: to evaluate the antifungal effect of AEC on the identified fungi present in corn tortillas.
Materials and Methods. One kg samples of corn tortillas were obtained from the capitals of five states of Mexico (Sonora, Nuevo León, Michoacán, Oaxaca y Yucatán). Fungi were identified by their morphology and molecular biology. Moreover, the minimum inhibitory concentration (MIC) against AEC was determined. The effect of E, I, and AE on Aspergillus niger was evaluated with the Gompertz model.
Results. Two fungi were isolated from corn tortillas purchased in Nuevo León, Sonora, Yucatán, and Michoacán, and one fungus from those purchased in Oaxaca. The following fungi were identified by molecular biology in corn tortillas: Aspergillus longivesica and Curvularia spicifera from Nuevo León; Aspergillus niger and Penicillium brevicompactum from Sonora; Aspergillus sp. from Oaxaca; Mucor sp. and Aspergillus flavus from Yucatán; Penicillium herquei and Curvularia racemosus from Michoacán. The MICs were 200, 400, 800, 400, 800, 400, 800, 800, and 400 µg mL-1, respectively. AEC, E, and I at a concentration of 800 µg mL-1 delayed the growth exponential phase of Aspergillus niger, while AE did not show any effect.
Conclusion. AEC could be a natural alternative for prolonging the corn tortillas′ shelf life.
Keywords: Eugenol, isoeugenol, eugenyl acetate, Aspergillus niger.
Figure 1. Fungal structure by optic microscopy (40X), isolated from corn tortillas from Morelia, Mich (A: Penicillium sp. and F: Mucor sp.), Monterrey, N.L. (B: Aspergillus sp. and G: Curvularia sp.), Oaxaca, Oax (C: Aspergillus sp.), Hermosillo, Son (D: Penicillium sp. and H: Aspergillus sp.) and Mérida, Yuc (E: Aspergillus sp. and I: Mucor sp.).
Figure 2. Growth of fungi in PDA isolated from corn tortillas from Morelia, Mich (A, Penicillium sp. and F, Mucor sp.), Monterrey, N.L. (B, Aspergillus sp. and G, Curvularia sp.), Oaxaca, Oax (C, Aspergillus sp.), Hermosillo, Son (D, Penicillium sp. and H, Aspergillus sp.) and Mérida, Yuc (E, Aspergillus sp. and I, Mucor sp.).
Figure 3. Antifungal effect of AEC, E and I on the growth of Aspergillus niger on PDA 96 h after de incubation at 25 ± 1 °C.
Figure 4. Kinetics of mycelial growth of Aspergillus niger on PDA for 96 h of incubation at 25 ± 1 °C. yVal= y values; Fit 1=curve with adjusted data.
Table 1. Minimum inhibiting concentration (MIC) of clove essential oil on fungi (250 conidia) isolated from corn tortillas.
Table 2. Kinetic parameters of the effect of the clove essential oil (AEC), eugenol (E) and isoeugenol (I) on the mycelial growth of Aspergillus niger incubated at 25 ± 1 °C for 96 h, obtained with Excel DMFit 3.5.
