Can defect: springers and flippers

Cans are an excellent and durable container. However, they are potentially dangerous if they have been processed incorrectly or the can fails in storage.

Care also not to overfill the cans, since this may result in the development of springers or flippers. Dangers arise from canned goods as a result of changes in the contents, defects in the canning, impurities from the can or the use of representative and coloring agents.

By pressing the ends of a can with fingers, it will detect flippers and springers and soft and hard swells. Springer - a can with one end permanently bulged. When sufficient pressure is applied to this end, it will flip in, but the other end will flip out.

Flipper is a can that normally appears flat; A slight distension of one end of the container where outside pressure will return the end to a normal position but will cause the other end to flip out. Flippers result from a lack of vacuum.

This condition is actually the beginning of a hydrogen swelling or due to an insufficient exhaustion or over-filling beyond the capacity of the can. Flippers or springers are most frequently caused by inadequacies of vacuum and headspace, and only rarely by microbial spoilage.
Can defect: springers and flippers

Can hard swell

The swells occur due to the production of H2 (formed by action of acids of food and tin plate), CO2 or other gases (as a result of decomposition of contents by microorganisms).

The spore-forming anaerobes Clostridium can be either predominantly proteolytic or saccharolytic but both activities are normally accompanied by gas production causing the can to swell.

Hard swell

In hard swell, can ends are rigidly hard and there is no effect of pressure except bursting or leakage of the can. Different from soft swells that can with both ends bulged that may be dented by pressing with fingers.

These events tend to develop successively and become of value in predicting the type of spoilage that might be in effect.
Can hard swell

Hydrogen swells

Cans may sometimes swell as a result of chemical action. In high-acid foods, hard swells are often hydrogen swells, which result from the release of hydrogen gas by the action of food acids on the iron of the can.

These hydrogen swells can often be distinguished from microbiological spoilage since the appearance of swelling occurs after long periods of storage and the rate at which the can swells is usually very low.

If hydrogen is produced into the can headspace, the process is called rapid electrolyte detinning. Electrolyte action is accelerated by oxygen and by the coloring matter (anthocyanins) of red fruit. Cans affected with hydrogen swell may show varying degrees of bulging form flipping to blowing. If the tin punctured, there is emission of hydrogen gas, which is colorless and burns on the application of a flame.

Products traditionally involved have been fruits (e.g. pineapples and pineapple juice, tomatoes, peaches), but canned vegetables such as mushrooms, green beans, spinach and carrots have also demonstrated this problem.
Hydrogen swells