Food manufacturers make significant investments to ensure freshness and performance throughout the shelf life of their product. To achieve this goal they must have a package seal that will hold up under dynamic stresses such as distribution, storage and handling. If the packaging fails to maintain hermetic integrity, spoilage and microbial growth can result. This can cost the manufacturer a lot of money and can damage brand image.
Maintaining the integrity of a packaged food is a complex process that requires attention to packaging components, the closure/sealing process and seal integrity testing. A combination of tests provides a comprehensive approach to monitoring package integrity and can minimize waste, prevent product recalls and protect the brand reputation of the company.
A nondestructive approach to evaluating the seal integrity of a flexible pouch is the bubble emission test. This test identifies leaks in a closed package by measuring the internal pressure the seal can tolerate, utilizing a standard differential of 13.8 psi. The test is particularly useful for modified atmosphere packaging (MAP) and for packages that will be shipped over mountain ranges or into unpressurized cargo holds.
Another method for evaluating seal integrity is the compression test, which evaluates the strength of a sealed package by applying a uniform amount of force to the perimeter of the package. The test also examines the structure of a seal to distinguish between fused and peelable seals, since each type requires different amounts of pressure to induce failure. The test involves cutting a section of the package perpendicular to the seal being tested, securing each end of the sample with screw clamps, and applying a specified amount of force. The results are analyzed visually or with the aid of a commercial device that measures the difference in echo frequencies between the sample and control package to determine the degree of hermetic integrity loss.