食品贮藏过程中重金属有害物在陶瓷釉及食品界面的迁移机制研究

Domestic ceramics as a major food contact materials, the release of heavy metals from its glaze layer has a direct negative impact on hygiene and safety of food. However, research in our country on safety of ceramic food contact material is at the starting stage, and its foundation is weak. The obvious disparity of standard permissible limits of release of heavy metals from ceramic materials in contact with food between our country and the developed country, has become the major bottleneck of both export of ceramic products and development of ceramics industry in our country. The research work of this project will firmly focus on the migration mechanism and the influence law of heavy metals from ceramic glazes into food, the concrete contents of which include: (1) according to the research on microstructure of ceramic glaze layer, heavy metals existing form in ceramic glaze layer and characterization of glaze layer matrix corrosion, to elucidate migration mechanisms of the major heavy metals from ceramic glaze layer into food and to explicate the mutual influence between different mechanisms; (2) to study the influence of food property, storage condition and microstructure of ceramic glaze layer on the migration mechanism; (3) to seek for migration characteristics and law of the major heavy metals from ceramic glaze layer into food or food simulant; (4) to establish a multi-mechanism coupling migration prediction model of the major heavy metals from ceramic glaze layer into food or food simulant; and (5) to characterize the key parameters of the model. This project aims at the revelation of migration mechanism and law of the major heavy metals from ceramic glaze layer, and is expected to provide theoretical and technical foundation for effective prediction and control of the migration of heavy metals from ceramic food containers into food.

日用陶瓷作为一种重要的食品接触材料，其内层釉中重金属溶出量直接影响所接触食品的卫生与安全。然而我国在陶瓷食品包装材料安全方面的研究刚刚起步，研究基础甚为薄弱，重金属溶出量的限量标准与发达国家的差距明显，成为制约我国日用陶瓷产业发展和陶瓷制品出口的主要瓶颈。本项目开展陶瓷釉中重金属有害物向食品溶出迁移机理及影响机制研究，具体内容包括：基于陶瓷釉层组织结构、重金属离子存在形式与状态、釉层基体腐蚀表征研究等阐明釉中主要重金属溶出迁移机理及其不同机理作用的相互影响；研究食品特性、贮藏条件以及釉层组织结构等对溶出迁移机制的影响；获得陶瓷釉中主要重金属向食品（模拟液）溶出迁移特性与规律；建立基于多机制耦合的陶瓷釉中主要重金属溶出迁移预测模型；表征模型关键参数。本项目旨在揭示陶瓷釉中主要重金属溶出迁移的机理与规律，为有效预测、控制陶瓷食品容器中重金属有害物向食品迁移提供理论与技术基础。

食品安全与消费者的身体健康密切相关，更是社会经济稳定发展的重要保障。日用陶瓷作为一种重要的食品接触材料，其内层釉中重金属溶出量直接影响所接触食品的卫生与安全。本项目通过开展陶瓷食品接触材料中重金属有害物向不同酸性食品模拟物的迁移试验与理论研究，揭示了食品贮藏过程中食品特性及贮藏环境对重金属元素向食品迁移的规律和影响机制，获得了食品特性pH值、食品贮藏时间和温度与重金属迁移量之间的量化关系。同时，本项目对陶瓷釉层中重金属向食品的迁移机制进行了深入研究。陶瓷釉层是熔融在陶瓷制品表面上一层很薄（约120μm～140μm）的均匀的玻璃质层，其物理化学性质与玻璃相似。它在与水接触时，其反应机理受到多种因素的影响至今没有完全达成一致。釉层中重金属元素向食品的迁移受釉层玻璃网络基体溶解的影响，其迁移机理也没有被完全确定。项目申请人之前的研究发现重金属向食品的迁移在低温下为以离子交换反应为主的选择性浸出行为，高温下重金属的迁移更偏向于基体溶解。通过本课题的研究，发现重金属的迁移在高温和低温下都存在选择性浸出和基体溶解两种机制，迁移开始都是选择性浸出为主，随着时间的进行，基体溶解反应机理占主导。温度不同，迁移机理发生转变的时间点不同，随着温度升高，转折点会更加提前。特别是在70℃以上高温环境下，几乎是接触瞬间即以基体溶解反应为主要机理。此外，通过对重金属元素与陶瓷釉层网络主体元素硅在釉层与食品中的比例关系研究，进一步确立了离子交换和基体溶解两种共存的重金属迁移机制。在之前的研究中建立的重金属迁移模型是基于离子交换机理的扩散模型，未考虑基体溶解的影响。本项目在原来扩散模型的基础上，考虑了玻璃基体溶解对迁移的影响，引入了基体溶解导致的移动边界项，并基于此建立了多机制耦合的陶瓷釉层重金属迁移预测模型，为有效控制陶瓷釉层中重金属的迁移提供了技术思路。