Canning and Fish Packaging Technology

Unit 5 - Changes in canned foods and spoilage

5.2.2.3. Microbial causes
During pre-processing, that is during the preparation of raw material or after packing but before retorting, the bacteria present in food may spoil it to some extent. Though heat processing kills the bacteria, the quality of food cannot be improved. If the extent of spoilage is less, it goes unnoticed, but if the extent is more, then it is called as pre-process spoilage. In pre-process spoilage pH changes to some extent, gases are produced and the food becomes soft. When canning machines break down in the factory or if there is power failure or for any other reason, half completed cans, filled and seamed cans held up for a long time before heat processing, pre-process spoilage occur. In such cans flipper or springer may be observed. It may not lead to hard swell. In such cans, living microorganisms or their spore may not be found. But microscopic examination show more dead cells. The quality of food inside may not be good. By minimising delay in each stage and from one stage to the other and also by observing good hygiene and sanitation practices, this type of spoilage can be minimised.