Definition of canning and its importance in preservation of food
Common steps involved in canning operations
Advantages of canning.
1.1.Introduction to Canning
It has been a great struggle for man from the beginning not only to collect and produce food but also to preserve the produced food. The quantity of food to be filled varies with the size of the can. The practice of keeping the food in metal/glass containers and heat processing came into existence in the late 18th century. This is achieved either by using steam or by creation of vacuum by a pump. Can closing should be airtight preventing the exchange of gases between atmosphere and inside of the can.
Heat processing (Retorting): Retorting is a process where the closed cans are subjected to heat processing at high temperature to destroy spoilage and pathogenic microorganisms. The temperature and duration of heat processing depend on the type of food, size and shape of can
Cooling of the cans: After heat processing, cans are cooled immediately either in air or more commonly in water to the ambient temperature. This is done by can seamer. The shelf life is about 2 years.
* Wide range of food products can be preserved. This process of preservation is referred as canning, which is the verb form of the word can which means a metal container.
1.2.Definition of canning
Canning is a method of food preservation in which food is packed in metal or glass or plastic containers, sealed air tight and heated sufficiently to destroy the spoilage, pathogenic and food poisoning organisms making the food safe for consumption.
1.3.Steps involved in canning
The steps involved in the canning process are as follows.
Pre-processing operations: Depending on the nature of the food, different preprocessing operations are carried out. were developed from the very early days of civilization. Washing, separation of edible parts, cleaning, cutting into desired size and shape, brining, precooking, blanching, frying etc are done prior to filling of the can. Ordinary room temperature storage is sufficient.
* As inedible portions of foods stuffs are removed, it represents concentrated form of food
* Canned food has long shelf life measured in years not in weeks or months. The removal of air prior to can closing creates vacuum in the head space.
Can closing/seaming: Can closing or seaming is a process wherein, the lid and the body of the can are tightly sealed. The difference in canning method for various foods stuffs lies in this stage.
Can filling: The preprocessed food is filled in to the cans along with suitable filling medium. This is the most important step in canning. Sufficient space has to be provided between the lid and the top layer of the food.
Exhausting: The exhausting is the process to remove the air and gases inside the filled cans. Hence, several food preservation methods such as sun drying, salt curing and drying, smoking, chilling using ice etc. Cooled cans are dried, labeled and stored.
* Canned products are safe and will not cause any ill health (or allergy etc)
* Canned product are ready to serve products and hence instantly available for consumption with little or no further preparation for the table.
* Canned product can be made available at any place any time.
* Canned products do not require special storage facility such as cold storage.
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