Seal integrity is extremely important for preventing contamination or spoilage of a canned food product. Here is why proper canned food sealing is important and most effective method for evaluating seal integrity for canned food.
Why Seal Integrity Is Important
Poorly sealed cans can cause major problems for food businesses. In addition to product waste, improperly sealed cans may result in spoilage of the product or contamination. Both of these scenarios will result in costly product recalls.
Any company that sells canned food products risks its reputation if a canned product is recalled. Product recalls can result in lawsuits from vendors, liability for injury and illness and other monetary losses. Product recalls can also attracted the attention of food safety regulators, which often results in fines and penalties.
How to Perform Leak Tests
Spoilage may result from leakage when improper pressure control during the retorting and cooling operations results in stress on the seam of the can. Visual observation is often used in examining the seam and detecting leakage traditionally.
Examination ofthe defects and general exterior conditions of the can, check on the quality of the seams, confirm if there are any mechanical defects, perforations, rust spots and dents.
Pressure and Vacuum Leak Testing
Pressure and vacuum tests are recommended for modern detection of invisible micro leaks, either in side seams or double seams. A vacuum test is conducted by applying a vacuum to the canonce it is sealed with product inside. If leaks exist, the vacuum level surrounding the can will drop, indicating air leaking out of the can. The vacuum leak test is recommended over pressure tests because it is considered to be more effective.
Mead Jar Testing
A mead jar test is a non-destructive test that can determine the leakage paths for finished cans that have double seamed ends. It is typically used for dried or semi-dried products that have been vacuum packaged. The test is not generally used for items that have been thermally processed in metal cans.
Air Pressure Testing
Air pressure tests are performed in order to detect container leakage that is caused by perforations, pinholes and defective side seams. It is also helpful for finding the source of double seam leaks. Air pressure testing can result in distortion of the double seams, which can result in minute leakage paths being sealed off or false leakage paths being produced. As a result, it is generally recommended to use this testing method along with fluorescein testing or penetrant dye testing.
Other methods for leakage testing that are currently under development include the laser holographic method and the helium leak test.
