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 products.

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 contamination.

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.

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.

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.

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.

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.

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 bills.
• 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.

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.

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

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 other countries.

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.

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.