X-ray micro-CT is a non-destructive imaging technique that allows internal food and packaging structure to be investigated. These systems allow 3D objects to be visualised and measured without any destructive sample preparation.

Conventional imaging techniques generally produce 2D images of the surface, or a cross-section of a sample. Labour intensive methods, e.g. sectioning to produce thin slices, or chemical fixation to produce contrast, are frequently used to prepare samples for these 2D imaging procedures. However, these processes are usually destructive and the resulting 2D information is often insufficient to draw conclusions regarding the 3D structure. Moreover, these destructive techniques can introduce artefacts which confuse the interpretation of these measurements.

This white paper looks at some example applications of X-ray micro-CT to food structure and packaging analysis.

Basic principle

Objects are placed within an X-ray beam and rotated. The X-rays are absorbed by the object. Dense regions cause more absorption than low-density regions, and thicker regions of the object cause more attenuation than thinner regions. A series of shadow projections are recorded. The shadow image produced at each angle provides information about the size and density of the object, in that orientation. Computer software is used to reconstruct the 3D shape from a series of shadow projection images, recorded over 180° (or more).