When deciding what packaging to use for a particular product, the packaging itself cannot be evaluated in isolation. It must be viewed as an integrated whole with the food or drink (or any other material) it contains and with the processes and environment to which it is going to be subjected. Consideration of these three elements - the package, its contents, and its handling - collectively as well as individually is essential in assuring end product quality and safety.

Not only must packaging retain its integrity and have the correct physicochemical characteristics to do the job, it must also not affect the product by causing taints or loss of quality. Campden BRI's expertise in all these areas enables us to take this holistic approach. We have a range of facilities for packaging analysis and for strength and integrity testing, as well as both chemical and sensory taint analysis capabilities.

Different materials have very different properties and uses, and have to withstand different types of treatment. This brief fact sheet looks at some of the types of analysis that can be carried out on glass, metal, plastics and paper/board packaging to determine both its inherent fitness-for-purpose and whether it has been damaged or compromised in any way.

GLASS

Internal pressure resistance testing

When carbonated drinks are filled into glass bottles, or the liquid becomes carbonated through fermentation in the container, the glass needs to be able to withstand the internal pressure exerted on it by the liquid. Internal pressure resistance testing can be used to evaluate the suitability of the glass being used - perhaps during product development, or as a result of a change in glass suppler or a change in product formulation. It is also very useful as part of an investigation into failure of the glass.

The test can also be used for plastic bottles used to pack carbonated drinks.

A video demonstrating internal pressure testing can be viewed at:

www.campdenbri.co.uk/videos/packaging-pressure-video.php

Impact testing

Glass can be subjected to impact during storage and distribution. A pendulum impact tester can be used to replicate 2 objects colliding. This is useful for assessing the robustness of the container in relation to knocks and bumps during distribution. A pendulum is raised and dropped towards the glass sample at an angle; the energy absorbed by the sample on failure (i.e. breakage) is calculated. This can then be related to the container's ability to withstand impacts during distribution.

Thermal shock resistance

Some types of glass are not suitable for processes which involve significant and rapid changes in temperature. However, glass is becoming increasingly popular again as a container for heat-preserved (either hot-fill or in-pack processed) foods. Therefore, it is important to verify that the grade of glass in the containers being used is suitable for the process that will be applied. This will help minimise problems with new products or when changes are made to the container, contents or process. Thermal shock tests are designed to test the weaker outer surface of the glass container. The container is stabilised in hot water for a specified time (with water both inside and outside the container), and then it is immersed in cold water up to the neck whilst still containing hot water.