Quality maintenance of Washington navel oranges and control of fungal decay using CaCl₂, chitosan, and Rhodotorula mucilaginosa treatments

This study was conducted on “Washington navel” oranges to reduce mold spoilage and maintain regular quality characteristics during shelf life at ambient conditions by CaCl₂ (1%), chitosan (1%) and Rhodotorula mucilaginosa (yeast, 10⁸ CFU/ml), treatments as biological eco-friendly agents. All applied treatments reduced both disease incidence (averaging 6.68–14.70%) and severity (averaging 4.40–9.00%) compared to the control (14.70 and 11%, for disease incidence and severity, respectively). The most effective treatments were R. mucilaginosa in combination with either CaCl₂ or chitosan, followed by R. mucilaginosa alone. Among the applied treatments, R. mucilaginosa in combination with chitosan was the most effective treatment followed by R. mucilaginosa in combination with CaCl₂ to reduce weight loss, maintain higher firmness, vitamin C, titratable acidity (TA%) and total soluble solids (TSS%). Additionally, fruit peel color, evaluated by lightness and Hue angle (h°), was not significantly affected by the applied treatments, indicating no negative impact of such treatments on peel color. In conclusion, R. mucilaginosa in combination with chitosan or CaCl₂ treatments can be used as a biological agent to effectively control blue and green rot and maintain regular fruit quality. However, using chitosan, CaCl₂, or yeast alone did not achieve the desired effect.