HOT WATER TREATMENT (HWT) OF MANGOES

Post harvest losses in mangoes in majority of varieties / hybrids has been to the tune of 30%. The major problems are pests like fruit fly and anthracnose fruit rot and Non-uniform ripening. These are causing heavy revenue loss and heavy damage to mango exports. To overcome this problem, IIHR, Bangalore has standardized Hot Water Treatment technology for Mango. "Dipping of fruits in hot water of specific temperature for specified periods for the purpose of disease control, insect damage, disinfestation or uniform ripening is known as Hot Water Treatment ". This is also most important in quarantine treatment for exports of fruits. This also has additional benefits like removal of surface pesticide residues, helps to remove sap of fallen in fruit surface during harvest and facilitates washing also.
The hot water treatment plants requires the use of a specialized equipment, to control the temperature of the water bath essential for the process. A circulating pump or some other method should be utilized to mix the water to assure uniformity of temperature within the tank. Temperature monitors should be placed within the treatment tank.
The ratio of volume of water to fruiting stock should be large enough to prevent a significant drop in temperature when the stock is added. Sometimes fungicides are added to hot water to bring about efficient post harvest disease control. After treating with HW, the fruit should be allowed to cool and dry in preparation for grading and packing.

HW treatment for Export purpose.

The mangoes must be treated in the country of origin at a certified facility.

Fruit temperature should not be less than 20oC before starting the treatment.

Fruit must be sub-merged atleast 4 inches below the water's surface

Water must circulate constantly throughout the treatment

The duration of the hot water dip treatment is determined based on the origin, shape, and weight of the mangoes.
The above technology has been perfected at this Institute and a pilot hot water treatment plant on a small scale has been fabricated. This technology has been recommended for -
It was observed that 460C for 65min treatment could control both fruit fly and anthracnose and 520C for5min could control anthracnose only. The capacity of hot water treatment plant at 460C for 65min treatment is 0.25 ton/hour and at 520C for 5min is 1 ton/ha.
HW treatment was more effective in controlling the spoilage of mangoes during long term storage under normal LT conditions and reduces the spoilage by more than 50 per cent compared to fungicide treatment. At 130C, HW treated fruits of mangoes could be stored for 21-28 days (depending on the variety) without any spoilage.
HW treatment also helped to reduce the spoilage during ripening of Control Atmosphere (CA) stored mango fruits.