Post harvest Management of Horticultural Crops (2+1)

Vapour Heat Treatment

Vapour Heat Treatment

Vapor heat treatment is a method of heating fruit with air saturated with water vapor (humidified by injection of steam) at temperatures of 40–50°C to kill insect eggs and larvae as a quarantine treatment before fresh market shipment. Vapor heat was developed specifically for insect control. The temperature and exposure time are adjusted to kill all stages of fruit fly infected produce(mango). The treatment consists of a period of warming (approach time) which can be faster or slower depending on a commodity’s sensitivity to high temperatures. Then there is a holding period when the interior temperature of the produce reaches the desired temperature for the length of time required to kill the insect. The last part is the cooling down period which can be air cooling (slow) or hydrocooling (fast).

Eg.: Treatment of citrus, mango, papaya and pineapples at 430C in saturated air for 8 hr and then holding the temperature for a further 6 hr.

For control of papaya fruit fly, fruit should be exposed to 430C and 40% RH for 11hr., followed by 430C and 100% for 8 hr.


Problems - Hot water and vapour heat treatment may causes both internal and external damage to produce if not properly done -

• Injury to fruit such as increased weight loss
• Acceleration of colour development
External damage - includes peel browning, pitting, or yellowing of green vegetables. Tissue damage caused by heat will also result in increased decay development.
Internal damage - causes poor pulp color development, abnormal softening, the lack of starch breakdown and the development of internal cavities as in case of mango and papaya. In addition, the fruit can soften quickly or show abnormal softening where some areas of the flesh remain hard while others soften.