Contamination Evaluation Begins With Light Microscopy
Food Safety Magazine - May 2014
Consumer complaints are often related to the presence of foreign material in food products and other consumer products. The foreign material has to be identified for safety reasons, as well as to maintain good customer relations. The foreign material may be present as small particles, requiring analysis techniques that are suitable to these sizes. Examination of the foreign material using a stereomicroscope can provide preliminary identification of the unknown material and informs selection of the proper method for further analysis of the particle. Most importantly, the stereomicroscopic examination may provide information about how the particle was generated, and whether it was incorporated into the product during manufacturing or inserted by the customer.
Stereomicroscopes are low magnification, binocular microscopes that provide a 3D image of a sample. Compared with other instruments, they are low cost and easy to use. They have a large working distance, and can be mounted on a free-swinging arm to allow for examination of larger samples. The working distance also provides room for sample isolation and preparation of small particles for subsequent analyses. Stereomicroscopes can be used with several methods of illumination to best observe a sample, including oblique or side light, reflected light (coaxial or top light), and transmitted light.