A simple non chemical solution may be the postharvest treatment that would effectively inhibit ripening and rapid disease development in fruits.
This developed as a study conducted by Mr. Antonio Acedo et al at the Postharvest Technology Laboratory in VISCA, Leyte, found that hot water dip (HWD) stops the ageing of banana (Latundan and saba) and mango (carabao and indian mango).
High perishability has been one of the major problem besetting the Philippine Fruit Industry. Serious postharvest losses are attributed to the physiological behaviour of fruits – rapid ripening sets in and postharvest diseases usually develop when mature fruits are harvested.
Using several treatments, the study revealed significant results. A 10- minute direct dip in 47-49 degrees Celsius water temperature delayed the ripening of latundan by four days compared to untreated fruits. A delay of five days in fruit ripening with saba banana indirectly (enclosed in plastic bag) dipped in 47-49 degrees Celsius water temperature was also achieved. Researchers said HWD treatment could inhibit fruit ripening in banana without adversely affecting the quality of the fruits such as taste, texture and peel color. They said HWD may have stopped the ripening of fruits by inhibiting the biosynthesis of the ripening hormone called ethylene.
Moreover, HWD was found effective in minimizing the postharvest disease in banana such as anthracnose and finger rot. A relatively high temperature suppressed the growth and even killed the pathogens which are the causal agents of diseases. The researchers also noted that indirect treatment in 47 to 49 degrees Celsius water temperature was effective for disease control in both latundan and saba. They concluded that the hot air inside the plastic bag during the indirect HWD application probably heated the fruit tissues thus suppressing the growth of fungus more effectively than direct application.
HWD treatment is also found effective in the case of carabao mango. Dipping in 51-53 degrees Celsius water for 10 minutes delayed ripening for 10 days while increasing the water temperature for 54-56 degrees Celsius water further delayed ripening by 2-3 days more thus expanding the fruit storability and freshness.
The results also established the effectiveness of HWD in controlling the postharvest diseases such as anthracnose and stem end rot in carabao mango. It is concluded that a higher water temperature of 54-56 degrees Celsius is required to significantly retard the development of anthracnose and stem end rot. A double HWD treatment , consisting of 10 minute dip in 40 degrees Celsius water followed by 10 minute dip in 52-53 degrees Celsius water is also found more promising treatment for disease control.
Researchers of the study recommended to develop future studies on other postharvest treatment and the use of hot water additive such as calcium and other anitsensescent or antimicrobial compounds to develop postharvest technologies that are cheap, safe and residue free.
Source: BAR Today July – September 2000, Mary Charlotte O. Fresco
For more information contact Mr. Antonio Acedo et al, postharvest technology laboratory Department of Horticulture VISCA Baybay leyte