Corrosion in Tinplate Cans Used for Food Storage, Part 1: EIS Analysis of BPA-NI Coating

Tinplate cans with polymeric coatings are commonly used for food storage. Due to health concerns related to bisphenol A (BPA), coatings with BPA not intentionally added (commonly referred to as BPA-NI) coatings are currently being considered. Thus, understanding the degradation of BPA-NI coatings is critical for predicting can integrity. In this study, the corrosion of tinplate cans with a BPA-NI coating exposed to different solutions was studied using electrochemical impedance spectroscopy (EIS). To accelerate the corrosion process, cans were stored at 49°C for varying times prior to testing in various solutions. EIS was performed first in the original storage environment and then in 3.5 wt% NaCl to investigate the performance of the can coatings. Separately, EIS was also used to investigate degradation of the coating in the headspace region. The EIS results provide insights into the degradation of the BPA-NI coating and the corrosion of cans arising from the exposure to different food chemicals.