XEDA International - 1397 Route nationale 7 - ZAC LA CRAU - 13670 SAINT ANDIOL - France - Tél. +33(0)4 90 90 23 23 - Fax +33(0)4 90 90 23 20 - info@xeda.com

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Immersion treatment for fruit and vegetables. The bins of product move forward on a roller conveyor through a curtain of chemical solution. This allows total coverage of the fruit with the treatment solution, which is then collected in a tank below for recycling via a high capacity pump.


Thermofogging is a treatment process for fruit and vegetables in store, by the generation of a fine fog containing the active ingredient.

Thermofogging does not generate waste water as the aerosol coats individual fruit and vegetables in store, delivering protection with lower amounts of active ingredient compared to conventional drenching or a dipping.

Thermofogging gives:

These advantages make thermofogging an essential element in Xeda International’s

Low Environmental Impact (LEI) approach to crop treatment.


This machine is designed to generate a fog from certain approved formulations.

The principle is based on a combination of high speed airflow and high temperature (without producing combustion gases or residues).

Main features :

The «fog »

Correct fog quality is essential for successful treatment. The fog produced has to deliver a complete and even coating of the fruit, vegetables or potatoes throughout the store. Storage in bins or in boxes must be arranged so as not to impede the circulation of fog throughout the store. Store filling must be done to facilitate fog circulation. Low speed internal recirculation fans will assist the even distribution of the fog in store.

To be fully effective the fog must have a narrow distribution range of small and homogeneous droplets. The target size for 90% of the droplets is between 0.1µ and 5µ. Numerous studies carried out over a number of decades show that electrofog technology is most succesful, when it produces the desired droplet size range:

          - Analysis of fog generation to measure the droplet size

           - Analysis of the size distribution of droplets generated from different formulations, measured by laser

C E A Study’s summary graph:

TNO study c

Measurment carried out with Electrofog and different formulations of various active ingredients.

Adapted formulation of CIPC : XEDAMATE

Adapted formulation of imazalil : XEDAZIL AEROSOL

With a formulation of the same active ingredient which is not intended to be applied by electrofogging, the droplet distribution is heterogeneous and shows a larger size and wider size distribution.

The production of aerosols/fog

A good formulation is the basis for the production of good quality aerosol for the treatment of stored fruit and vegetables. The capacity of the aerosol to deliver a homogeneous coating on fruits and vegetables in store will depend on obtaining uniform small droplets. If droplets are too small, there is a risk of coalescence and condensation; if they are too large they do not adequately circulate or coat the target products, and drop to the floor or drip on the fruit or vegetables. If droplet dispersion is poor, there is a risk of phytotoxicity, and reduced efficacy of treatment.

Droplet diameter is an important criterion: for every halving of the diameter, the number of droplets generated is multiplied by eight. Accordingly we believe that two parameters are essentials in the production of aerosols for successful post-harvest treatment:

Combustion devices usually used for treatment in greenhouses or protected crops are occasionally employed for potato treatment. Aerosol production based on an internal combustion engine, is subject to variation, and can generate a large droplet size distribution combined with a risk of introducing combustion gases with undesirable residues for foodstuffs.

Droplet size range from different methods/products:

Advantages of Electrofog treatment

Post-harvest treatments are used in a specific context aimed at preserving product quality while ensuring food safety. Post-harvest treatments fit into a sustainable and environmentally friendly approach. Post-harvest treatments take place in confined location (packing house, potato store, grain stores) which limits the risk of generating diffuse wastes into the environment.

Waters contaminated by run-off from dipping or drenching must be retained for treatment. Thermofogging almost totally removes any risk of run-off, and with a reduced rate of active ingredient for the same level of efficacy


Thermotherapy is a treatment for fruit and vegetables with hot water at temperatures between 40 and 60°C with a brief contact time, of between 20 seconds and 3 minutes. The hot water can be used in three different processes:

Hot water at temperatures between 40 and 60°C gives very good protection against many fungi and apple fruit scald. The limitations of this technique are the risk of phytotoxicity from very high temperatures on the skin of sensitive varieties, and the absence of residual protection against fungi. The fruit and the bins are perfectly sanitized following the treatment, but are liable to re-contamination by fungal spores in the atmosphere.

Using hot water at temperatures of between 45 and 52°C, chemical use can bereduced by up to two thirds as treatment efficacy is three times greater than at ambient temperature. As a result the waste treatment water contains 66% less residue.

Using hot water at temperatures between 45 and 48°C, in combination with essential oils, provides similar control to hot water alone at 50 to 52°C, and avoids the skin damage caused by high temperatures, while increasing the preservation of the fruit by several months, due to the presence of natural products. The use of clove oil gives an additional antioxidant effect.

We have developed an alternative use of cold/hot temperatures for particularly sensitive fruit by which high temperatures sanitise the skins while subsequent low temperatures reduce the danger of phytotoxicity and over ripening

Xeda have developed machines for the different application methods:


Hydrocooling / hydroheating enables the rapid cooling or heating of fruit and vegetables directly after harvest. This technique is carried out by immersion or dipping of fruit and vegetables in water at 0.°C or at around 50°C. By cooling down the fruit core in a short time allows:

There are three types of hydrocooling:

The same machine can also be used for thermotherapy, particularly for citrus and peaches palletised in boxes or in bins, replacing the cooling system by a heating system with an external heat source . The water from the boiler transfers its heat to the water through an exchanger placed in the lower tank. The external layer of the fruit is warmed up in few minutes. The hydrocooling process becomes the hydroheating process and the advantages are those of thermotherapy, such as:

Hydrocooler cabin with inflatable walls



Xeda International especially designed a machine – BIOWAXER - to apply the coating wax for fruit, Xedasol-L ( Xeda patent). This machine is constituted by a series of brushes at the entry and by a rollers conveyor, on which, fruit, while progressing are:

Net width : 1000 mm

Total width : 1600 mm (indicatif)

Length : 6000 mm

Total height : 2 000 mm (indicatif)

Feeding height : Minimum 850 mm - Maximum 1100 mm

Chassis and rollers : Inox AISI 304

Installed electric power : 7 Kw  alimentation 3P+N+Ground

Wax consumption : Between 4 et 5 litres per ton of fruits (approx.)

Specificity : Non ATEX certified conditions

Capacity : 4 tons per hours (approx.)

- Coated with the natural wax applied through a dosage pump and 14 full independent full-cone stainless steel nozzles, operated individually by electro valves controlled by a PLC.

- Cold-air dryer where the air passes through the rollers and the fruit, under a negative pressure for the complete safety of the system ( non ATEX conditions), vacuumed by the turbine above the machine.

- A tank under the rollers collects the drained liquids to evacuate them to the sewage. The machine is also equipped with a pneumatic progressor which allows the automatic evacuation of the fruit in case of sudden stop.

The wax Xedasol L does not require hot air dryer and leaves, leaves after its evaporation a moisture protective film, which resists to cold and/or humidity (no whitening, no scaling, etc.). The protective film created this way “seals” the fruit, reducing dramatically the water loss and the gas exchanges, preserving flavours, firmness, crunchiness and juice, insuring a glossy and shiny fruit with a longer shelf life. The shine of the film does not fade away in the time like in case of water waxes.


XEDA International - 1397 Route nationale 7 - ZAC LA CRAU - 13670 SAINT ANDIOL - France - Tél. +33(0)4 90 90 23 23 - Fax +33(0)4 90 90 23 20 - info@xeda.com

Dipping machine