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Executive Summary:

Hot water treatment is a technology that has been created with keeping human health utmost in mind. The use of heated water or water vapors has been found out as a very effective method in meeting out the quarantine requirement.

This method not only helps out the environment but also is a cheaper way of destroying insects/ pests or disease in perishable items like fruits and vegetables. This is a good thing for the third world countries like Pakistan.

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This technology of quarantine control was approved by USA in 1984 and according to WTO (world trading organization) agreement any exporting country will have to agree and imply such pest harvest treatments.

The innovative Hot Water Treatment provides practical and vital solutions for the agriculture industry, solutions that are economical and are also energy-saving. And in addition to this advantage to the grower is an increase in high quality output that is produced for the selling in markets.


Hot water treatment is a process that is used in killing pesticides and insecticides in fruits and other perishable items. As the name suggests in this process the items are dipped into hot water for specific time duration and the temperature of the water is also maintained at a certain level. The time period and the temperature required for the treatment is decided by the type of result required e.g. either to kill pest/insects or to get rid of a disease called Anthracnose which makes health fruits and vegetables rotten. Researches have shown that to kill fruit flies larva within the pulp of a fruit like mango the time and the temperature required would be 45-48 centigrade for 60-70 minutes.

                                    Diagram of hot water treatment tank

The process can be done by Hot water immersion, high temperature forced air or by heated vapour.It can not only be used on mangoes but also on papayas, bananas, persimmons and on a variety of vegetables and flowering plants. This method was first used by Bakers and Co-workers in 1929 against the Mediterranean fruit fly.

However due to the popularity and cheapness of chemicals, interest in these sort of experiments waned, but now because of the high rise in chemical prices and the general negative effects on human health this method is again gaining popularity.


The earth’s environment has been a long standing issue of debate between environmentalist and the business community. Many methods used in the business field in regards to products like fruits, vegetables and plants have been frowned upon by many and not without just cause; many pesticides and insecticides used not only harm the environment but also have a negative effect on the human health.

The hot water treatment that has been proposed creates the idea that proper quarantine control can be obtained without causing problems in the eco-system. This process will not only sustain the agricultural practices but will also protect and enhance our soil resources and ultimately achieve the greater balance between the business of agriculture and the surrounding environment.

Due to the awareness of harmful effects of chemicals on fruits and vegetables, people have started to complain about the items that have chemicals sprayed on them; this can cause problems for a lot of food and plant growers and sellers for their products can be rejected by the buyers. Adopting this process will eliminate this problem for good.

 Heat treatment technology is a relatively simple, non-chemical alternative to methyl bromide that can not only kill quarantine pests but can also control some post harvest diseases. Unlike methyl bromide, heat treatments does not raise significant health risk issues created by it’s chemical residues and are more appealing to consumers than methyl bromide fumigation. Furthermore, hot water treatment has been approved as a proper quarantine treatment by the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) against pests (mainly fruit flies) for several perishable items.

In most cases, heat treatments are performed by the country whose product is to be exported. The temperature, duration, and application method has to be according to the commodity and must be very precise in killing pests without damaging the item. All perishable commodities response to the heat treatment depending on their natural properties, the temperature and duration of treatment, as well as the mode of heat application also depends on the fruit. If not properly applied, heat treatments may cause damage.


Some of methods of Hot Water Treatment are as follows:

Hot-Water Immersion
High Temperature Forced Air
Vapor Heat

Hot-Water Immersion: –

Hot-water immersion consists of submerging the commodity in a hot-water bath at a certain temperature for a specific period of time. For perishable food commodities, proper treatment can be achieved by heating the core of the fruit to 43°–46.7° C with the times varying from 35 to 90 minutes. Variations are noted for different commodities and pest species. Hot-water immersion also has the additional benefit of controlling post harvest microbial diseases such as anthracnose and stem end rot. Immersion of non-food perishable commodities (such as cut flowers and bulbs) in hot water 43.3°– 49° C  for 6 minutes to 1 hour is effective in destroying insect pests while maintaining product quality. This method can be used on papayas, guavas and bananas but is not recommended for fruits that have stones in it.

High Temperature Forced Air: –

Recirculated air that has been heated is forced over fruit surfaces to raise the temperature to a level that is lethal to pest species. Heated air treatments of 40°–50° C for less than eight hours are becoming more common for fruit fly control in tropical commodities. Condensation on fruit surfaces is prevented by keeping the dew-point temperature 2°- 3° C below the dry-bulb temperature throughout the duration of the test. This control of temperature and relative humidity helps in preventing the fruit from desiccation and scalding. Hot air is not recommended for avocado, lychee, and nectarines but can be used for grapefruit, papaya, and mango.

Vapor Heat: –

Vapor-heat quarantine treatment uses heated air thick with water vapor to heat up perishable food commodities to a specified temperature and then hold that temperature for a certain period of time to ensure that all pests such as fruit fly larva within the commodity are killed. Typically, the fruit pulp temperature is to 43.3°– 44.4° C during a period of 6 or 8 hours and then held at the required temperature for another 6 or 8 hours. Vapor heat is used for treatment of grapefruit, orange, bell peppers, eggplants, papayas, pineapples, tomatoes, zucchini, squash etc.


 The capital costs for heat treatments are only slightly higher than those for methyl bromide on a per ton commodity basis. Operating costs for heat treatments, on the other hand, are eight times higher than those for methyl bromide primarily because of longer treatment times and higher energy costs. It is hoped that operating costs will decrease in the future as the number of heat treatment facilities increase. Although the total costs for perishable commodity treatment with heat is seven times greater than that with methyl bromide, the relative proportion of this cost is small when compared to the value of the commodity. They will not only sell as organically treated food items but will be more appreciated by the public.


The idea of Hot Water Treatment (HWT) has had a vary of responses which go from excitement to skepticism, probably because it has been widely known that perishable items should be cooled as soon as possible not heated up to stop the decaying process.

However there are some limitations to this procedure one being that it does not have an overlong effect of quarantine control, so much is dependent upon the degree of sanitation and the kind of environment the item is kept in after dipping in the hot water.

Hot Water can also reduce storage life of different kinds of fruits and vegetables if some kind of an inquiry occurs during the process.

Energy cost is also an issue that has been raised in the Hot Water Treatment.

Hot water treatment is highly not suitable for perishable items such as asparagus, nectarines, avocados, or leafy vegetables. Because their shelf life is very little.


In reference to the sanitary problem, growers or the shipper can go to the different health and sanitation department in their areas and find out the proper method of protecting their processed items. They will not only get information on how to handle their fruits and vegetables but what should be done in what kind of climatic condition.

Injury to the item can be reduced if some experiments are first done on a small case to see what time and temperature suits for what item to gain the desired result.

There is also a way to side step the energy problem by converting the expenditure made on cooling item as soon as they are harvested to heating up water for the water baths.


Hot Water Treatment (HWT) is a method that is not only cheap but also enables us to help out our eco-system. There are limitations in this process but the rewards are not small. It has been seen in Hawaii that the growers who have adopted this system have seen a decrease in their labor costs and an increase in environmental protection.

Human health over time has become a very important issue and these methods gives up the guarantee that when conserving or storing our food supply, we do not have to resort to chemical use, but can use a natural way to solve natural problems without heavy repercussions on our soil and on our health’s.

Some of the methods of hot water treatment would includes vapor heat, high temperature forced air and hot-water immersion. Heat treatments for disinfestations of fruit and vegetable are being used since 1929. Heat treatment technologies relatively simple they are basically non-chemical alternative to methyl bromide that can kill quarantine pests (insects and fungi) in perishable items, as well as control some post harvest diseases. Heat treatments do not pose a health risk that sometimes is caused from chemical and because of that it is more appealing to the customers.


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A.Hara, R. Yamakawa, E. Mersino, N. Nagata, K. Sewake, and R. Hamasaki, 1998, Hot Water Treatment for Cut Flowers and Propagative Materials,

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Fan, X., Annous, B.A., Mattheis, J.P. 2006. Use of hot water surface treatment of whole fruit and gamma irradiation to maintain quality of fresh-cut cantaloupe,

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WTO, WTO Agreements,

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S. T. Koike, UC Cooperative Extension, Monterey Co.     W. D. Gubler, Plant Pathology, UC Davis                         G. T. Browne, USDA Crops Pathology and Genetics, UC Davis (Reviewed 4/05, updated 5/05)   UC IPM Pest Management Guidelines: Strawberry

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APHIS. 1993. Plant Protection and Quarantine Treatment Manual. United States Department of Agriculture. Animal and Plant Health Inspection Service.

Williamson, M. 1996 (August). Personal communication. Michael Williamson. University of Hawaii at Menoa. Menoa, Hawaii.

Couey HM. 1989. Heat treatment for control of post harvest diseases and insect pests of fruits.

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