Can UVC radiation be useful in prolonging the shelf life of mangoes?

• UVC treatment effectiveness in prolonging the shelf life of mangoes with and without pre-treatment infection symptoms. • Developing a mango black spot model to predict the UVC light transmitted through these spots. • UVC light cannot effectively penetrate mango black spots to inactivate fungus. • Selecting mangoes with minimal visible infection symptoms for UVC treatment to extend their shelf life. This paper examines how the initial condition of mangoes impact the effectiveness of UVC treatment. Specifically, we treated two distinct groups of mangoes with different initial conditions: one group with almost no visible infection and the other with slight infection symptoms. Mangoes from each group were exposed to varying doses of UVC light using a 275 nm ( ± 5 nm) UVC LED cavity. Our results show that UVC treatment was effective for mangoes with almost no visible infection pre-treatment. Conversely, for mango group with slight infection symptoms pre-treatment, UVC radiation was ineffective in reducing disease symptoms. Afterwards, we analyzed UVC light penetration through mango black spots by measuring its transmittance through black spots of varying thicknesses. An optical model of mango black spot was then constructed; to our knowledge, this is the first time a UVC model constructed for this purpose. The results indicate that UVC light cannot effectively inactivate fungus that has already penetrated the mangoes. Consequently, we recommend selecting mangoes in good initial condition for UVC treatment to achieve the effectiveness in prolong their shelf life. This work aims to improve UVC treatment technology for mango preservation and provide guidance for process optimization.