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What is Steam Sterilization?

Steam Sterilization is the process which removes, kills, eliminates all types of biological agents like bacteria, fungi, spore forms, the unicellular eukaryotic organism such as plasmodium which are present in the region of surface, medication or a compound such as biological culture. So, the process does not involve in changing the physical characteristics of any product like the aroma or color. It only changes the microbial characteristics& makes the product safer to be consumed.

Sterilization is done in different ways like chemical, heat, irradiation, filtration, and high pressure. Sterilization kills, eliminate or deactivates all types of biological agents and forms of life which are present.

Steam Sterilization is simple decontamination method but very effective.

Sterilization can be done to all types of Seeds, Nuts, Powder and wholes, different types of herbs and spice products. It also helps to increase the shelf life of the products. It is quite an expensive affair but a very useful process.

The Steam sterilization is achieved by exposing products to saturated steam at a high temperature of 121°C to 134°C. Products are placed in a device which is known as autoclave and heated through pressurized steam to kill all spore and microorganisms.

The two most common types of steam sterilization are – the Gravity displacement autoclave and the High-speed pre-vacuum sterilizer.

Other types of steam sterilizations:

• Small table-top sterilizer
• Portable steam sterilizer
• Emergency sterilization or flash sterilization [form of gravity displacement]

Sterilization of Low-Acid Foods:

The sterilization of low-acid foods (pH greater than 4.6) is generally carried out in steam vessels called retorts at temperatures ranging from 116 to 129 °C (240 to 265 °F). The retorts are controlled by automatic devices, and detailed records are kept of the time and temperature treatments for each lot of processed cans. At the end of the heating cycle, the cans are cooled under water sprays or in water baths to approximately 38 °C (100 °F) and dried to prevent any surface rusting. The cans are then labeled, placed in fiberboard cases either by hand or machine, and stored in cool, dry warehouses. 

Sterilization of Canned Foods:

The sterilization process is designed to provide the required heat treatment to the slowest heating location inside the can, called the cold spot. The areas of food farthest from the cold spot get a more severe heat treatment that may result in overprocessing and impairment of the overall quality of the product. Flat, laminated pouches can reduce the heat damage caused by overprocessing.

A significant loss of nutrients, especially heat-labile vitamins, may occur during the canning process. In general, canning has no major effect on the carbohydrate, protein, or fat content of foods. Vitamins A and D and beta-carotene are resistant to the effects of heat. However, vitamin B1 is sensitive to thermal treatment and the pH of the food. Although the anaerobic conditions of canned foods have a protective effect on the stability of vitamin C, it is destroyed during long heat treatments.

The ends of processed cans are slightly concave because of the internal vacuum created during sealing. Any bulging of the ends of a can may indicate a deterioration in quality due to mechanical, chemical, or physical factors. This bulging may lead to swelling and possible explosion of the can.

Advantage of Steam Sterilization:

• It can be done for powder, anhydrous oils, ad glass.
• It helps to reach the surfaces of instruments that cannot be disassembled.
• Steam Sterilization is done whenever possible on all items which are Semi critical and critical which are moisture and heat resistant.
• Steam sterilizers also are used in healthcare facilities to decontaminate microbiological waste and sharps containers.
• It is non-toxic to environment, patient, and staff.
• Sterilization cycle is easy to control and monitor.

Disadvantage of steam Sterilization:

• The items which are to be steam sterilize they must be heat and moisture resistant.
• Ointments and oils cannot be steam sterilized.

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