Biocontrol of Green Mold of Orange using Some Yeasts Strains and their Effects on Postharvest Quality Parameters

Abstract

Three isolates of yeasts, Candida sake (Cs), Pichia gluilliermondii (Pg) and Pichia membranifaciens (Pm) were evaluated for their activities in reducing postharvest green mold decay of orange fruits caused by Penicillium digitatum. In vitro experiments, all tested isolates inhibit the growth of Penicillium digitatum. In vivo experiments, treating fruits 15 days before harvest and after harvest or only after harvest (natural and artificial infection of fruits) by three isolates of yeasts significantly reduced the disease severity in natural and artificial infection of fruits compared with untreated fruits (control). Pichia gluilliermondii (Pg) was the best yeast than others isolates in controlling the disease in artificial infection. All treatments significantly decreased fruit weight loss percentage (%) for nine weeks comparing with control. Results also indicated that all isolates significantly reduced the undesirable fruits percentage during cooling storage period (5°C) compared with control. Prolonging cooling storage at 5°C for nine weeks significantly increased total soluble solids percentage of all treatments and control. Total acidity slightly decreased after cold storage period, while post-harvest treatments with the Pichia gluilliermondii caused significant decrease in total acid. Vitamin C was gradually decreased as storage period prolonged, for both control and tested treatments. No constant effects between all treatments and controls, except post harvest treatment fruit with Pichia gluilliermondii which caused high decrease in ascorbic acid content compared with controls.