Canning and Fish Packaging Technology

Unit 3 - Unit operations in canning

3.2.3.7.3.2.Ideal vacuum inside the can
Most people agree that there should be vacuum inside a food can. However there is a lot of disagreement regarding the exact quantum of vacuum. According to B.I. Standards, for fish packed in round tall cans, vacuum should be 10cm. However, for fruit cans it should be more than this. In other countries, it is 12-15’’ for small cans and for large cans it is 9-12’’. For sardine packed in quarter dingley cans it can be even less (just negative pressure is sufficient). However, if the fish canners try to maintain 25 to 30 m of Hg pressure inside the cans, there will not be any fear of rejection of the product by any country.