Storage quality alterations in rambutan fruit sprayed preharvest with calcium chloride (CaCl2)
The storage life of rambutan fruit, a unique tropical fruit, is mainly limited by skin/spintern browning generation and disease deterioration. Postharvest calcium chloride (CaCl2) treatments have been reported to be effective in maintaining quality in a range of fresh produce. In this study, developing rambutan fruit were sprayed with a solution of CaCl2 and Prochloraz (an imidazole fungicide) in order to study the effects in relation to improving the storage quality. Four different treatments were prepared: 300 ppm Prochloraz; 0.3% (3000 ppm) CaCl2; a combination of the two; and water (as the control). The four different treatments were sprayed thoroughly (20 L tree-1) on to Rongrien rambutan inflorescences and trees for three different times during fruit development, starting from fruit setting at 1.0-cm diameter, then green mature (ca. 80 days after anthesis), and lastly fruit breaker (ca. 100 days after anthesis). Fruit at pink stage were harvested, packed into perforated polyethylene bags, and stored at 13°C and 90-95% RH. Fruit sprayed with the combination of CaCl2 and Prochloraz showed the most brightness (highest L* values) at harvest and L* value still remained high on day 12 of storage. The orientation position of trees in the field affected the peel colour. While titratable acidity of fruit pulp (aril) increased during storage, soluble solids reduced slightly without significant differences between treatments. Weight loss of all treatments slightly increased, with 2.7% average at the end of storage. On day 12, bacterial growth of fruit treated with CaCl2, and CaCl2 + Prochloraz were less than 3 log CFU g-1, while tap water sprayed fruit (control) was at above 5 log CFU g-1. Moreover, for fungal growth, there was less than 2 log CFU g-1 in rambutan treated with Prochloraz alone or CaCl2 + Prochloraz, compared with 4 log CFU g-1 in the control. As a result, preharvest application of the combination of CaCl2 + Prochloraz is significant in improving the postharvest quality of rambutan fruit.
Wongs-Aree, C., Buanong, M., Boonyaritthongchai, P., Promboon, J., Chaiyaporn, T. and Tongtao, S. (2018). Storage quality alterations in rambutan fruit sprayed preharvest with calcium chloride (CaCl2). Acta Hortic. 1213, 275-280
Nephelium lappaceum L., agricultural practice, calcium chloride