This study was performed to explore the efficacy of combining more than one postharvest treatment in maintaining some quality attributes and reducing fungal pathogenicity in cold-stored guava fruits. The investigated postharvest treatments included the control, CaCl 2 (4%), lemongrass oil (2 dm 3 kg -1 ), gamma (γ) irradiation (0.2, 0.4 and 0.6 kGy), 0.4 kGy γ irradiation + CaCl 2 (4%), and 0.4 kGy γ irradiation + lemongrass oil (2 dm 3 kg -1 ). The studied physiochemical attributes included weight loss, decay percentage, fruit firmness, total soluble solids (TSS), titratable acidity (TA), and vitamin C content. Different fungal species were also isolated from decayed fruits and were identified as Alternaria alternata, Alternaria solani, Aspergillus niger, Botrytis cinerea, Fusarium solani and Rhizopus stolonifer. The severity of infection for the different fungi was determined, and an in vitro antifungal assay was conducted for lemongrass oil. All the investigated treatments generally reduced decay and water loss percentages, and controlled TSS, TA and vitamin C decrements that occurred during cold storage. On the other hand, higher irradiation doses generally increased fruit softness, and the 0.4 kGy γ dose did not contribute to the overall fruit quality when coupled with CaCl 2 and lemongrass oil, compared to CaCl 2 and lemongrass oil treatments alone.Ke y wor d s: cold storage, fungal growth, postharvest, Psidium guajava L.

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Biosynthesis of nanoparticles (NPs) is a rapidly expanding topic; the junction of nanotechnology and biotechnology has gained a lot of attention as a result of the growing need for ecologically friendly and effective food safety technologies. Sweet green bell pepper (SGBP) is a perishable vegetable with a short shelf life and a high risk of fungal illness throughout the handling and storage procedure. This study aims to compare the efficacy of different chitosan preparations (irradiated and nanoparticles) in preserving SGBP. Chitosan powder was irradiated by Co 60 γ-radiation with a total exposure dose of 40 kGy. Six solutions were prepared; chitosan, irradiated chitosan, and nanocomposite (chitosan, mucilage) with two concentrations, 0.5%,1% for each one. The treatments were applied for the six groups of SGBP fruits by immersion in one solution for two minutes and stored in the refrigerator condition for 28 days. Microbiological and physiochemical analyses were determined weekly. All treatments generally decreased the total microbial count, especially at 1% concentration of the irradiated chitosan treatment. The fungal growth was completely suppressed by treatments with concentration 1%. In addition, the results of chemical analysis showed that the treated fruits retained the acceptable quality characteristics of the consumers compared to the untreated fruits.