Effects of Acid Resistance on Migration Behavior of Vitreous Enamels

Abstract

A wide variety of cookware and utensils are continuously used throughout the world. Owing to the high mechanical and thermal properties, metallic surfaces such as cast iron, steel and aluminum are frequently used in this field. However, during cooking, metal atoms can enter the food from the metal surface due to the pH of the food, relatively high cooking temperature and contact time of the processed food. This condition is called migration and when the human body gets more metal than it needs to take daily or the harmful elements enter the body, it causes many diseases, notably cancer. Enamel coating is an inorganic coating that has high heat capacity owing to the silicates in their chemical structure, high hardness and durability owing to their amorphous structure, chemical resistance and abrasion resistance. Hazardous compounds can be present in the enamel coatings which comes from the minor components used in production of frit compositions such as NiO and CoO to ensure chemical bonding in interface. These compounds can leach or migrate into food and from there into human body. Therefore, some regulations and standards have been developed to protect human health. ISO 4531:2018 standard states an ICP analysis with limited release of 16 elements. However, some of these elements have a vital importance in the enamel coating technology hence it was aimed to replace the required oxides without causing a change in the enamel structure. In this study, a typical borosilicate frit composition containing a high proportion of RO2 groups, was used to provide heat resistance to the enamel structure and resistance to organic acids. The migration properties were investigated according to ISO 4531:2018 standard. It is stated that healthy and conforming to standards enamel compositions can be developed.