Food packaging seal integrity testing ensures that packages remain sterile and hermetic. It is performed as part of food safety inspections, HACCP, production quality control and after changing distribution methods. The objective is to detect small leaks or potential leaks in the package that could expose the product to cocci-shaped or rod-shaped bacteria, as well as larger leaking water droplets.
Several techniques are used for non-destructive evaluation of seals and the rest of the package including pouches, sachets, cans, trays, and rigid containers. The procedures and equipment used vary according to the type of package and construction, so it is important to obtain detailed test information from the package manufacturer or supplier.
For example, a pouch may be inspected by squeezing it along its perimeter in order to evaluate its tightness and the integrity of the head and side seals. Other tests include the dye penetration test (ASTM F3039 - 15) which involves applying a specific color of dye to one side of the seal area and examining it after a specified period of time to see if the color has moved into the inside of the package.
Another method is to use the bubble emission test (ASTM F2338 - 08(2013)). This nondestructive testing uses internal pressure that a package's seals can withstand. It is especially useful for evaluating flexible and rigid packaging such as pouches, sachets, or the seal on rigid containers.
A final method is to perform a vacuum decay test (ASTM F2338 - 10(2013)). This nondestructive test applies a vacuum to the entire surface of a package. It is particularly useful for evaluating the seals on rigid packages such as cans or trays.