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

Abstract

This study demonstrated a method to investigate corrosion formation in the headspace of canned chicken noodle soup. In this method, Selected Ion Flow Tube–Mass Spectrometer was used to identify and quantify chemical compounds in raw and cooked chicken noodle soup and those that migrated towards the polymer coating of the metal cans. Scanning electron microscopy (SEM) was used to detect the appearance of breaches in the coating of the tested cans, and energy dispersive X-ray spectroscopy (EDS) allowed for analysis of the elemental composition of the internal walls of the tested cans. Inductively coupled plasma–mass spectrometry (ICP-MS) provided information about the migration of iron and tin from the internal walls of the cans into the packaged soups. SEM images showed that breaches developed in the coating of the tested cans when corrosion occurred. The EDS analyses showed that tin and iron exposures were associated with extra peaks in the EDS. These peaks were attributed to sulphur. From the results obtained, it was concluded that the process of heat retorting contributed to the formation of sulphur-containing volatile compounds that bonded to the coating in the headspace of the tested cans. These then penetrated the protective coating and facilitated avenues for other oxidative chemicals in the product to cause corrosion and staining. Results from the ICP-MS analyses showed that tin and iron subsequently migrated from the corroded cans toward the chicken soup. These results thus showed how corrosive compounds in a retorted food initiated corrosion in metal cans.