Articles
PHYSIOLOGICAL EFFECTS OF HOT WATER TREATMENTS ON BANANA FRUITS
In banana, HWT have been used for quarantine purposes and for reduction of chilling sensitivity and crown rot in ‘Cavendish’ cultivars (Marrero et al. in preparation). In this study we examined the effects of HWT on the ripening of ‘Santa Catarina Prata’, an AAB banana cultivar grown in Hawaii for local consumption.
Samples of thirty randomly selected fruits were dipped in water baths at 24, 42, 47 or 52°C for 30 min.
Chilling treatments involved the storage of the fruits at 5°C for 24 hours immediately after HWT. After the treatments, the fruits were allowed to ripen naturally at room temperature (about 24°C). The course of ripening was followed by monitoring respiration and ethylene evolution as well as changes in firmness, soluble solids content and peel color.
The ethylene evolution and ACC oxidase activity of 1 mm-thick disks of peel and pulp were also assessed.
Chilling damage was rated according to a subjective scale from 0 (no symptoms) to 5.
HWT affected the respiration and ethylene evolution of whole fruits as well as the ACC-oxidase activity of peel and pulp.
A treatment temperature of 52°C suppressed the climacteric rise of ethylene in both peel and pulp, causing irregular ripening (incomplete degreening of the peel and low soluble solids and high pH of the pulp). The 42°C treatment did not affect the ethylene evolution of peel tissue but reduced considerably that of the pulp.
The 42°C treatment also caused a slight reduction of the chilling sensitivity of the fruits, whereas temperatures of 47°C and above increased this sensitivity.
HWT show potential for the control of postharvest diseases of banana but should be cautiously applied to avoid negative effects on commercial fruit quality.