Methods for identifying microplastics in food systems

In the 1970s, scientists began reporting the presence of plastic objects in millimeters and later in the micrometer range in the environment and drinking water. In 2004, small plastic particles found in the environment were first named microplastics, and in 2008, during an international research seminar, they were named plastic particles less than 5 mm in size. However, questions regarding acceptable sizes, polymer types, configuration, and origin of microplastics remain a subject of debate in the scientific community. The upper size limit is often set at 5 mm. Microplastics are classified by origin as primary or secondary. The methods used to analyze microplastics in various systems vary. Relatively simple methods include detection with the naked eye or using a light microscope. Microplastic identification is sometimes confirmed by staining or simple flotation (since plastic is less dense than water). However, identifying microplastics requires more sophisticated methods — thermal analytical or spectroscopic techniques. This scientific review focuses on methods for identifying microplastics in food systems. Various approaches to detecting and analyzing microplastics are considered, including visual identification, optical and electron microscopy, fluorescence microscopy, infrared and Raman spectroscopy, and thermal analytical methods. Particular attention is given to the advantages and disadvantages of each method, as well as their application in real-world conditions. The paper concludes by highlighting the potential of Raman microscopy and infrared spectroscopy for identifying microplastics in food systems and agricultural products.