Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality

Peña, William A. Lombana; Manosalva, Omar A. Nova; Guarnizo-Mendez, Hector F.; Castellanos, Nuri Andrea Merchán; Arango, Andrés Polochè

doi:10.3390/agriengineering8090398

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Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality

by

William A. Lombana Peña

¹

,

Omar A. Nova Manosalva

^1,*

,

Hector F. Guarnizo-Mendez

²

,

Nuri Andrea Merchán Castellanos

³

and

Andrés Polochè Arango

¹

Faculty of Engineering and Basic Sciences, Fundación Universitaria Los Libertadores, Bogotá 111221, Colombia

²

Electronics Engineering Department, Universidad El Bosque, Bogotá 111321, Colombia

³

Bioengineering Department, Universidad El Bosque, Bogotá 111321, Colombia

^*

Author to whom correspondence should be addressed.

AgriEngineering 2026, 8(9), 398; https://doi.org/10.3390/agriengineering8090398 (registering DOI)

Submission received: 21 July 2026 / Revised: 11 September 2026 / Accepted: 14 September 2026 / Published: 20 September 2026

(This article belongs to the Section Pre and Post-Harvest Engineering in Agriculture)

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Abstract

Cocoa (Theobroma cacao L.) postharvest quality can be compromised by fungal colonization across the farm-to-chocolate continuum, motivating non-chemical control options that can be engineered as unit operations. This study evaluates microwave (MW) irradiation (2.45 GHz) as a physical disinfestation process against Fusarium solani (F. solani). Experiments were conducted under a completely randomized design (CRD) by tuning MW power (140–210 W) and exposure time to reach predefined surface-temperature bands verified by infrared (IR) thermography. Post-treatment viability was assessed by incubation (27 °C, 7–10 days) and classified as Reduced Growth Rate (RGR; sublethal regrowth slower than control) or Death (D; no regrowth comparable to autoclaved negative controls). Outcomes were temperature-governed: RGR predominated in sublethal bands (60–80 °C), whereas consistent D occurred once surface temperature exceeded 80 °C. Thermodynamic modeling established a median lethal temperature (

L T_{50}

) of

81 . 0^{\circ} C

, and a 99% eradication threshold (

L T_{99}

) of

87 . 2^{\circ} C

. Maximizing the heating rate (

H_{r}

) to 0.381

^{\circ}

C/s at 210 W ensured rapid and profound cellular suppression. Scanning electron microscopy (SEM) corroborated severe ultrastructural damage (collapsed macroconidia and disrupted hyphae) under lethal conditions, and turbidimetric monitoring over 120 h showed sustained growth suppression in treated samples. These findings define a practical lethal threshold and power–time windows to inform MW scale-up as a postharvest unit operation while minimizing thermal residence time.

Keywords: cocoa; Fusarium solani; microwave irradiation; postharvest disinfestation; infrared thermography; thermal inactivation; power–time treatment adjustment; process kinetics; continuous processing; scanning electron microscopy

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MDPI and ACS Style

Peña, W.A.L.; Manosalva, O.A.N.; Guarnizo-Mendez, H.F.; Castellanos, N.A.M.; Arango, A.P. Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality. AgriEngineering 2026, 8, 398. https://doi.org/10.3390/agriengineering8090398

AMA Style

Peña WAL, Manosalva OAN, Guarnizo-Mendez HF, Castellanos NAM, Arango AP. Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality. AgriEngineering. 2026; 8(9):398. https://doi.org/10.3390/agriengineering8090398

Chicago/Turabian Style

Peña, William A. Lombana, Omar A. Nova Manosalva, Hector F. Guarnizo-Mendez, Nuri Andrea Merchán Castellanos, and Andrés Polochè Arango. 2026. "Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality" AgriEngineering 8, no. 9: 398. https://doi.org/10.3390/agriengineering8090398

APA Style

Peña, W. A. L., Manosalva, O. A. N., Guarnizo-Mendez, H. F., Castellanos, N. A. M., & Arango, A. P. (2026). Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality. AgriEngineering, 8(9), 398. https://doi.org/10.3390/agriengineering8090398

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Microwave-Induced Thermal Inactivation of Fusarium solani Strain Isolated from Cocoa Pods: Experimental Determination of the Temperature Threshold for Fungal Lethality

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