Abstract
Nanoparticles are used in industry for personal care products and the preparation of food. In the latter application, their functions include the prevention of microbes' growth, increase of the foods nutritional value and sensory quality. EU regulations require a risk assessment of the nanoparticles used in foods and food contact materials before the products can reach the market. However, availability of validated analytical methodologies for detection and characterisation of the nanoparticles in food hampers appropriate risk assessment. As part of a research on the evaluation of the methods for screening and quantification of Ag nanoparticles in meat we have tested a new TEM sample preparation alternative to resin embedding and cryo-sectioning. Energy filtered TEM analysis was applied to evaluate thickness and the uniformity of thin meat layers acquired at increasing input of the sample demonstrating that the protocols used ensured good stability under the electron beam, reliable sample concentration and reproducibility.
Highlights
The new emerging trend in the food industry exploits nanotechnology for versatile developments
Bright field images in Fig. 1a), 1b) and 1c) show nanoparticles embedded in the dried emulsions. t/λ maps in Fig. 1e), 1f) and 1g) were obtained through acquisition and application of the log-ratio method [9] of an unfiltered bright field (BF) image followed by an elastic image with 10eV energy slit centred onto the zero loss peak (512x512 pxl, 3s acquisition)
AgNPs were found positioned at different heights within the sample regardless of the dilution applied, demonstrating that the sample preparation method provided layers of significant thickness
Summary
The new emerging trend in the food industry exploits nanotechnology for versatile developments. One example is silver nanoparticles (NPs) used for food application For their antimicrobial properties, silver nanoparticles (AgNPs) are used in food supplements and various food contact surfaces (e.g. packaging, cutting boards, cutlery)[1]. The European Food Safety Authority emphasizes that for appropriate risk assessment of NPs in foods and feed, a particle size measurement in the hosting food products is necessary [6]. Standard sample preparation protocol for solid food samples e.g. meat involves such methods as resin embedding or freezing and sectioning of frozen material [7]. Both methods are laborious, require sophisticated equipment and technical skills.
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