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

Abstract

Tinplate cans with polymeric coatings are commonly used for food storage. Due to health concerns related to bisphenol A (BPA), BPA-free coatings are currently being considered. Thus, understanding the degradation of BPA-free coatings is critical for predicting can integrity. In this study, the corrosion of tinplate cans with a BPA-free 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-free coating and the corrosion of cans arising from the exposure to different food chemicals.

Investigation and mechanism of headspace corrosion in metal cans filled chicken noodle soup

“…As the corrosion reaction continued, the steel (iron) became exposed and susceptible to oxidation (Figure 11). In this situation, the exposed iron reacted with the organic acids and served as the anode 17,27,28 : …”

Mechanism of surface rust defects on tinplate strip steel during storage and transportation

“…In environments of high temperature, high humidity and high salinity, tinplate strip steel is susceptible to rusting. 28,29 Thus, the internal and external temperature, humidity and rust-inducing factors were monitored during storage and transportation to Southeast Asia, as depicted in Figure 6.…”