Streptomyces corchorusii, sodium silicate, and potassium silicate as eco-friendly alternatives to control fungal rot of navel oranges during cold storage and shelf life

Oranges undergo internal metabolic changes during cold storage and shelf life at ambient conditions, resulting in physiological and pathological disorders, mainly caused by Penicillium digitatum (green mold) and Penicillium italicum (blue mold), which decrease consumer preferences and marketability. To elucidate the effects of eco-friendly, safe treatments to control mold spoilage and maintain the quality of Navel oranges during cold storage and shelf life, freshly mature fruits were dipped for 15 min in 1% potassium silicate (PS), 0.5% sodium silicate (SS), or 10 6 CFU/ml Streptomyces corchorusii phytstc7 (STC), either alone or in combinations. The fruits were cold stored at (5 °C and 85–90% RH) for 50 days, followed by 3 days of shelf life (23 ± 1 °C and 60–70% RH). All treatments recorded no green mold incidence during 30 days of cold storage followed by 3 days of shelf life. However, after 40 and 50 days, the control treatment demonstrated a progressive increase in disease incidence, reaching 16.6 and 23.3%, respectively. Conversely, single treatments with PS, SS, and STC significantly suppressed disease development by 2.6%, 4.7%, and 2.0%, respectively. The combined treatment (PS + SS + STC) exhibited synergistic effects, and no visible disease was observed during 50 days of cold storage and 3 days of shelf life. This treatment also exhibited superior effects in maintaining regular physical and biochemical parameters of fruit quality. Other combinations, such as PS + STC and SS + STC, also performed exceptionally well, with a mean incidence of 1.3% and 0.7%, respectively. The severity of the disease followed a pattern similar to that of the disease incidence. Overall, postharvest dipping in 106 CFU/ml STC alone or combined with 1% PS and 0.5% SS could be an effective treatment to control green and blue mold and to retain the quality of ‘Navel oranges’ during 50 days of cold storage and shelf life.