Assessment of optimal postharvest treatment conditions to control green mold of oranges with sodium benzoate

Green mold, caused by the pathogenic fungus Penicillium digitatum, is the most important citrus postharvest disease in Mediterranean climate areas such as Spain.
Due to health and environmental issues, alternative methods to synthetic chemical fungicides are needed to control this disease.
The most effective concentration of the food additive and GRAS (generally regarded as safe) compound sodium benzoate (SB) was 3% (w/v), as determined in in vivo primary screenings with ‘Valencia’ oranges.
Optimal postharvest treatment conditions for maximum curative activity of SB against green mold were assessed on ‘Valencia’ oranges artificially inoculated with P. digitatum and dipped 24 h later in 3% SB aqueous solutions.
Tested dip temperatures were 20, 50, 53, 58, and 62°C. Dips at each of these temperatures were performed for two or more of the following immersion times: 5, 15, 30, 60, and 150 s.
Dip treatments at 50 or 53°C for 30 or 60 s resulted in reductions of green mold incidence of 60-80% on oranges incubated at 20°C for 7 days.
Furthermore, SB treatment at 50°C for 60 s reduced by about 85% the incidence of green mold on ‘Valencia’ oranges inoculated, treated, and stored for 2 months at 5°C and 90% RH. Therefore, heated SB aqueous solutions may be an interesting additional tool for integrated control of green mold in citrus packinghouses, especially for markets with zero tolerance to fungicide residues.

VIII International Postharvest Symposium: Enhancing Supply Chain and Consumer Benefits – Ethical and Technological Issues

L. Palou, P.A. Moscoso-Ramírez, C. Montesinos-Herrero

Citrus sinensis, Penicillium digitatum, GRAS compounds, alternative postharvest decay control

https://doi.org/10.17660/ActaHortic.2018.1194.33