Comparison of the effect of physical and chemical treatments on decay control, qualitative characteristics and some flavonoids of Thomson-navel orange fruits in cold storage

The decay of green and blue molds of Thomson navel oranges is one of the main causes of this product's decay and it can be a limiting factor in storing fruits. The aim of this study was to investigate the effects of wax, hot water, calcium chloride and commercial Tecto 60 fungicide treatments on reducing decay by inducing biosynthesis of flavonoid compounds and maintaining the postharvest quality of Thomson navel orange fruits. Fruits kept for three months in a cold storage at a temperature of 5 to 7 °C and a relative humidity of about 75 to 90%. Weight loss of fruits in waxed fruits was significantly lower than other treatments. The wounded and infected fruits did not have much chance of survival. None of the treatments were significantly effective on control of decay of non-wounded fruits. Total phenol content of fruit peel and flesh  decreased during storage. Hesperidin in the peel was at the highest level in Britex wax treatment. The highest amount of scoparon of fruit peel and flesh was in hot water and calcium + wounded treatments, respectively. Although the amount of scoparon in some treatments inhibited the germination of fungal spores, it did not have the expected effect in controlling decay. The use of Tecto 60™ and hot water can significantly reduce the decay of wounded and infected fruits. The treatments were not effective in controlling the deterioration of intact fruits, which indicates the importance of preventing mechanical damage to the fruit in the pre-harvest stage.