Investigation of foreign substances in food using scanning electron microscopy-x-ray microanalysis

• Published in: Scanning Vol. 20; no. 4; pp. 311 - 317
• Main Author: Charbonneau, James E.
• Format: Journal Article
• Language: English
• Published: New Jersey Wiley Periodicals, Inc 01.06.1998
• Subjects: Animals; cream of tartar; Crystallization; Electron Probe Microanalysis - methods; Food Contamination; Food Preservation; Food-Processing Industry; Glass - analysis; glass particles; glass-like particles; Magnesium Compounds; metal foreign objects; Metals - analysis; Microscopy, Electron, Scanning - methods; Phosphates; product tampering; Salmon; scanning electron microscopy; Spectroscopy, Fourier Transform Infrared; Struvite; x-ray micro-analysis
• ISSN: 0161-0457; 1932-8745
• DOI: 10.1002/sca.1998.4950200404

Scanning electron microscopy (SEM) and x‐ray microanalysis (EDS) were used to conduct forensic investigations on metal and glass foreign objects. SEM‐EDS is an excellent method for identifying metal foreign objects in food, such as wire, dental fillings, bone, and metal packaging, based on their element composition. From a determination of the extent of corrosion of a metal foreign object using SEM‐EDS, it is sometimes possible to determine whether the material has been processed with the food product. Case histories of processed aluminum, unprocessed nickel‐coated steel, and corrosion resistant stainless steel foreign objects are discussed. A potential product‐tampering problem involving a hole defect in a paperboard package was resolved using SEM‐EDS. Blue fibers found in the hole were found to contain brass particles from a ball point pen rather than a syringe needle. SEM‐EDS has been used to determine the elemental composition of glass foreign objects and is able to distinguish between many types of glass including container, electrical, and bakeware. A case history is presented to show that although container glasses cannot, in general, be distiguished from one another using SEM‐ED S, they can be distinguished by trace element semiquantitative spectrograghic analysis. SEM‐EDS can be used to distinguish glass‐like foreign objects from glass. Case histories of struvite crystals found in salmon and cream of tartar crystals found in grape juice are discussed. Fourier transform infrared (FTIR) identified the cream of tartar crystal as calcium tartrate, and this complemented the calcium, carbon, and oxygen components of the compound found using SEM‐EDS.