Effect of precooling with a solution of sodium carbonate on fruit rot and physiological changes in organic netted melon

The effect of precooling with a solution of sodium carbonate (SC, Na₂CO₃) on fruit rot and physiological changes in organic netted melon was studied. Melons were immersed in a cool solution of 2% Na₂CO₃ at 5 and 10°C until the temperature of pulp was 20°C. Fruit immersed in Na₂CO₃ at 30°C were used as the control. All fruit were kept at 13°C for 12 days. Results indicated that fruit immersed in 5°C had a lower disease incidence and severity during storage for 8 days than fruit immersed at 10 or 30°C. Moreover, precooling with Na₂CO₃ at 5°C maintained fruit quality and inhibited adverse physiological changes in melon, as indicated by low levels of weight loss, respiration, ethylene production, and the activity of the cell wall degrading enzyme, polygalacturonase. However, no effects on pulp color change, total sugar, and total soluble solids content of the melons were observed. These results indicate that precooling with a cool solution of sodium carbonate at 5°C can delay fruit decay and senescence in stored organic netted melon.