What Are The Problems Associated
With Fruits And Vegetables?
- The food products have different kinds of Bacteria, pathogens and
spoilage microorganisms on their surface and as these grow at a very
fast rate the freshness and shelf life of vegetables and fruits is
- Another major problem with the food product is that large amount of
residue of pesticides and insecticide is present on their surface which
is not only harmful but objectionable as far as standards are concerned.
What Is The Present Practice?
Generally Chlorine and other chemicals are
added to the washing water for the purpose of disinfection. The washing
water using chemicals leaves harmful by-products e.g. Chloramines &
Trihalomethanes etc. which is not only undesirable but use of chemicals is
also banned in some applications and the use of chemicals is being phased
How Microbial Counts Are
Controlled By Ozonated Water?
Ozone is a most efficient Natural
Broad-Spectrum Microbiological control substance and very reactive
Disinfecting agent. In case the vegetables are washed with strong Ozonated
water, not only the microbial load on to the surface get reduced or the
Ozonated water destroys any Bacteria, Viruses, Cysts and Pathogens on the
surface of food items washed with this water, in a very short duration.
The pesticides (which are long chain organic components) gets oxidized to
short chain components and finally into harmless elements. To conclude, the
Ozonated water or the strong disinfected water used for washing of
vegetables and fruits will make them fresh, longer shelf life and
Today use of Ozonated water is considered by most to be the best available
and advanced technology for washing fruits and vegetables, CIP and many
other applications and a much better alternative than using chemicals.
What Should Be Ozone Concentration
In The Treatment Water?
The Ozonated washing water should have
sufficient disinfection power to disinfect the vegetables or the commodity
being washed with it. In such an applications Ozone concentration in the
wash water should be comparatively higher in the range of 0.2 to 1.0 ppm.
Actual concentration required to be maintained depends upon the criticality
How Much Ozone (Gm/Hr) For Washing
The amount of Ozone required to be dosed, into
the wash water depends on number of factors e.g. Rate of flow of wash water,
Composition of water, Technique of Ozone dissolution, Product being washed,
Temperature of water, Initial Bacterial contamination and required
micro-biological quality of washed product. For correct estimation a
computer programme is generally used however as a thumb rule, 3.0 to 6.0
gm/hr Ozone is needed for a flow rate of 1,000 lit/hr.
What Are The Methods Of Ozone
High Ozone concentration water (0.25 to 1.0
ppm) is used for the purpose of washing fruits or vegetables. Special
techniques are used for mixing Ozone into the water for this application.
Following two types of Systems are generally utilized:
Washing of vegetables and fruits in an open
Vegetables and fruits are required to be washed in an open tray by using
spray of strong Ozonated water. The proposed System will produce strong
Ozonated water available in a spray nozzle.
The System consist of a storage tank equipped with a water pressure booster
pump which draws water from the tank, pass it through the Ventury Injector
(where the Ozone is injected) and later a Static Mixer (for improving Ozone
dissolution) and the Ozonated water is returned into a tank through a
There are two Solenoid Valves which control the flow of Ozonated water for
washing or re-circulation for increasing the Ozone concentration in the
water. At washing nozzle a push button is installed that changes the
configuration of water flow from re-circulation to washing and back to
(ii) Washing of vegetables & fruits in
washing tank :-
There is another system in which vegetables and fruits are kept in a
Stainless Steel basket and the basket is dipped in a special washing tank.
Water is drawn from the bottom portion of the washing tank, pressurize by a
booster pump, pass through a Ventury injector, a static mixer and later the
ozonated water is injected inside the tank on one side so that the complete
water in the tank is continuously agitated.
The tray with fruits and vegetables is kept in the washing tank, system is
started for pre determined time and after the set duration the tray is
lifted and vegetables or fruits shifted to another location.
What are the information Necessary
to design a Ozonated Wash Water System?
- Food item e.g. Fruits, Dry fruits, Vegetables, meat, fishes etc.
- Composition of water (TDS, Hardness, Iron & Manganese) used for
- Maximum flow rate of washing water and the maximum consumption per
- Lay out and location of the wash water storage tank
- If any pump is utilized for pressurizing the water,
- Sources of supply of water.