Particle size measurement of SiO2 nanoparticles in the food additive E 551 (SiO2) and E551-containing food products based on Scanning Electron Microscopy (SEM) imaging

Silicon dioxide (SiO2, amorphous silica) is a food additive approved in the EU with the designation number E 551. It is mainly used in powdered foods as a separating agent or anti-caking agent. Silicon dioxide as a food additive is under public discussion due to controversial views on the declaration obligation of the substance as an engineered nanomaterial. According to the Food Information Regulation (EU) No. 1169/2011, all food ingredients that are present in a food in the form of engineered nanomaterials must be clearly listed in the list of ingredients. The name of such ingredients must be followed by the word "nano" in brackets. So far, there are only very few E 551-containing foods on the market with nano-labelling of E 551 on the ingredient list. For all analysed samples, the outlines of the constituent SiO2 nanoparticles could be visualized within the SiO2-aggregates in high magnification SEM images (100.000x). Using the image analysis software ImageJ (v1.52p), at least 100 randomly selected particles were measured manually. The median minimum Feret diameter (Fmin) was defined as relevant measurand, based on the EU nano-definition recommendation and the EFSA -"Guidance on technical requirements for regulated food and feed product applications to establish the presence of small particles including nanoparticles”. This data set contains the chosen SEM images of all samples, showing the outlines (in green or yellow) of all measured particles. The Fmin sizes of each measured particle is added in the attached Excel file.

二氧化硅（silicon dioxide，SiO₂，无定形二氧化硅）是欧盟获批的食品添加剂，编号为E 551。该物质主要作为分离剂或抗结剂应用于粉状食品中。作为食品添加剂的二氧化硅目前正引发公众热议，原因在于其作为工程化纳米材料的标识义务存在争议性观点。根据《欧盟食品信息条例（EU）No. 1169/2011》，所有以工程化纳米材料形式存在于食品中的配料，必须在配料清单中明确标注。此类配料的名称后需以括号标注"nano"字样。截至目前，市场上仅有极少数在配料清单中标注了E 551纳米标识的含E 551食品。在所有分析样本的高倍扫描电子显微镜（Scanning Electron Microscope，SEM）图像（放大倍数100000×）中，可观测到构成二氧化硅聚集体的纳米颗粒轮廓。使用图像分析软件ImageJ（v1.52p），研究人员手动测量了至少100个随机选取的颗粒。基于欧盟纳米定义建议以及欧洲食品安全局（European Food Safety Authority，EFSA）发布的《针对经监管的食品和饲料产品申请的技术要求指南：确定包括纳米颗粒在内的微小颗粒的存在》，研究人员将最小费雷特直径的中位数（Fmin）定为核心测量指标。本数据集包含所有样本的精选扫描电子显微镜图像，图中以绿色或黄色标注出所有被测颗粒的轮廓。所有被测颗粒的最小费雷特直径数值均已录入附带的Excel文件中。