What is Ozone?
Ozone, a converted form of oxygen is a powerful
bactericide a nature's gift, microbiological control substance, due to its
high oxidizing capacity. The use of Ozone is a natural way of treatment and
disinfection process, which does not leave a trail behind or any harmful
substance, e.g. chemical bye-products.
Storage & Preservation
Micro-organisms are always present on food
items including spices, herbs, fruits and dry fruits. At comparatively
higher or lower temperature, the rate of growth of bacteria is lower,
however at normal temperature the micro-organisms grow at a very fast rate
and micro load on the food items increases. High counts adversely affect the
quality of products in respect to preserving freshness and duration of
Cold preservation temperature is different for different commodity. In case
of Meat & Meat products it is -20 to -30oC, while for Spices, Herbs and
Dry Fruits 5 to 10oC is maintained. The preservation temperature is based on
the fact that the bacterial growth is minimum and thus the food items remain
fresh for a longer duration.
Present Practice & Associated
During storage, processing and Cold Storage for
the control of micro-organisms or maintaining a bacteria free environment,
fumigation is used by using different chemicals. Fumigation being a manual
process, provides inconsistent disinfection and effect aroma, taste and
appearance of the products. It is also highly inconvenient to work after
fumigation, harmful for the operating personals and the person consuming the
Another major problem is loss of weight due to reduction of moisture
content from the product. To control this parameters humidifier are used.
High humidity and lack of illumination causes higher growth of micro
What are the Problems associated
Fumigation being a manual process, the quantity
of fumigant cannot be controlled accurately thus the process provides an
inconsistent disinfection and the irritating chemicals leaves residual
effect on to the products. It is not possible for at least 6 to 12 hrs. to
enter in the respective area after fumigation. Further, it is harmful for
the operating personals and the persons consuming the food items.
Restrictions are being imposed by several countries on the use of certain
fumigants and the phasing out schedules is being worked out. The list of
banned chemicals is increasing day by day.
How the freshness can be preserved
As logic, in case the microbiological load on
to the product is lower and the environment is free from any bacterial
contamination, there are very little chances of microbiological growth, the
main reason for spoilage and reduction of storage life.
A small Ozone Concentration into the environment can reduce the spoilage
micro organism very fast and almost to a zero level. In case, the spices,
herbs and dry fruits are exposed to controlled concentration of Ozone, the
microbiological contamination on to the surface of the ingredients can also
be brought down to a very low level. This is a technique utilized for
getting the higher shelf life or longer preservation duration.
What are the latest techniques in
Techniques are based on the principle that how
the growth of spoilage micro-organism can be minimized. Following new
techniques are generally coming in the forefront.
- Technology Of Controlled Environment : An inert atmosphere is
maintained in the cold storage generally by Nitrogen. A Nitrogen Gas
Generator is used for this purpose. During preservation of fruits,
Ethylene is generated which further accelerate the ripening process. In
addition concentration of CO2 is also important. Thus the quantity of
Ethylene and CO2 is required to be controlled.
This is a very effective preservation technique, however quite
expensive. The technique of controlled environment may not be
techno-economically viable in all the applications.
- Controlled Ozone Environment : This is a very effective &
economical technique and very appropriate in preservation of Herbs &
Spices either on lower or at normal temperature. Ozone's controlled
environment is maintained in storage space, which controls the growth
rate of micro-organism and improves the conditions of preservation.
How Microbial counts are
controlled by Ozone
Ozone a very strong oxidizer and efficient
Broad-Spectrum Microbiological control substance has powerful disinfecting
property. It destroys any Bacteria Viruses, Cysts and Pathogens in a very
short duration when it comes into contact with Air and Food items. Ozone is
very effective in a moist environment.
How Ozone can be used for normal
and cold Temperature Preservation
Growth of spoilage Micro-organism or any kind
of Bacteria can be retarded to a great extent in presence of Ozone. Thus if
a controlled environment of Ozone is maintained in a normal environment and
in case of Cold Storage, the Bacterial growth can be retarded even at a
slightly higher temperature then the usual preservation temperature
generally maintained in a Cold Storage.
What are the benefits of using
Ozone for a Cold Storage?
Following benefits can be obtained by using
Ozone in Cold Storage:
- A controlled environment of Ozone in a cold storage can maintain same
or better preservation even on a temperature higher by about 2 to 8o C
than the normal low temperature being maintained for the same commodity.
This will provide energy saving of about 8 to 18% on your electric
- If the food items are preserved in Ozone environment at the same
preservation temperature the duration of preservation will be enhanced
by 15 to 40%.
- Another additional advantage will be the reduction of undesirable
odour from the Cold Storage.
How do we estimate quantity of
Ozone (gm/hr) for a specific area ?
The amount of Ozone required to be dosed in a
packing room or a processing hall depends upon the size (volume) of the
room, presence of air handling system, present level of infection,
temperature of the hall, type of the product being processed, criticality or
the permitted level of Bacterial counts.
Ozone quantity is correctly estimated by taking various parameters into
consideration using a computer programme. However, for a rough estimation,
as a thumb rule, for a clean and low infection area 1 gm/hr Ozone is
required to be dosed for 6,000 Cu.ft. space while for the area of higher
bacterial contamination 1 gm/hr Ozone is needed for 3,000 Cu.ft. space. For
Cold Storage, 1 gm/hr Ozone is generally required to be dosed in 4500 Cu.ft.
space. This estimation is for a hall where the air is not changing and if
yes fresh air inlet is negligible. The dosing of Ozone is further controlled
by achieved Ozone Concentration in the area.
It is important that the Ozone Concentration in the work place where the
workers are present should not higher than the safe limit. After dosing the
estimated Ozone, in case the concentration of Ozone in environment is
higher, the amount of Ozone should be reduced.
What is the Concentration of
Ozone, required to be maintained in the Area ?
A very small Ozone Concentration of 0.05 to
0.08 PPM is adequate for sterilization of the affected area. Ozone
Concentration can be increased for fast sterilization upto 0.3 - 2.0 ppm if
persons are not present in the area in special cases
What is a Ozone Sterilization
System & How it works ?
Ozone is produced by Ozone Generator and
controlled quantity of Ozone is diffused into the environment. Controlled
quantity of Ozone is required to be diffused into the environment:
- o Using individual Ozone Generators of small capacity e.g. 0.5 to
0.75 gm/hr. or higher
- Through a network of diffusers into the affected area. The diffusers
are connected to a Central Ozonator.
- If an Air Handling System exists, it is better to inject Ozone at the
inlet of AHU. The injected Ozone gets mixed with the total air stream
and provides a uniform distribution and an effective disinfection.
Air Sterilization is a continuous and safe process. Ozone does not
leave any effect on workers and on the product and approved by FDA, USA and
How the Ozone Concentration is
Monitored and Controlled ?
Concentration of Ozone in air is monitored by
Ozone Monitors manufactured by 'CREATIVE OZ-AIR (I) PVT. LTD.'. For
Automatic regulation a feedback loop can be used. The monitoring system is
equipped with two stage correction outputs, which can correct the Ozone
output in the desired level. An improved system can be provided by a
continuous Analogue Control of Ozone output by a feed back for Ozone Monitor
(4-20 MA.). The system can be equipped with high & low level alarms,
which can be used for providing warnings or alerts.
What is the Limit of the Ozone
Concentration where persons are working ?
Ozone Concentration should not exceed more than
0.2 mg/m3 (0.1 ppm by volume) where operating persons are present, for eight
hours or more per work day, and no workers be exposed to a ceiling
concentration of Ozone in excess of 0.6 mg/m3 (0.3 PPM by volume) for more
than ten minutes. The Ozone expose levels have been set by the OSHA
(Occupational Safety and Health Administration) of USA & Canada.