SEM/EDS analysis for problem solving in the food industry

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For forensic investigation in the food industry, scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectrometry (EDS) is a powerful, often non-destructive, instrumental analysis tool to provide information about: • Identification of inorganic (and some organic) materials found as foreign contaminants in food products returned by consumers or detected during quality control inspections in the production facilities • Identification of wear particles found in production lines • Distribution of materials within a matrix • Corrosion and failure analysis of production equipment The identification of materials by SEM/EDS is accomplished through a combination of morphology by SEM imaging and the elemental composition of the material by EDS. Typically, the EDS analysis provides a qualitative spectrum showing the elements present in the sample. Further analysis can be done to quantify the detected elements in order to further refine the material identification. Metal alloys can often be differentiated even within the same family such as 300 Series stainless steels. Glass types can be identified by the elemental composition where the detected elements are quantified as the oxides of each element. In this way, for example, common window glass is distinguishable from insulation glass used in many ovens. Wear particles or fragments from breakage can find their way into food products. SEM/EDS analysis of the materials is an important resource to utilize when trying to determine the original source. Suspected source materials can then be sampled for comparative analysis. EDS X-ray mapping is another tool that is available to provide information about the distribution of materials within a matrix. For example, the distribution of inorganic ingredients in a dried food helps to provide information about the grind and blend of the materials.