The role of coatings in food storage containers, or any surface that comes into contact with food, is crucial. These coatings serve a dual purpose: they prevent food spoilage and contamination, and they shield the container from the corrosive properties of the food. Tins, for instance, are a popular choice for food storage due to their ability to protect food from air and light for extended periods. Moreover, tins, being conducting surfaces, allow for in-depth electrochemical studies of both themselves and their coatings.
While it would be ideal to predict the expiration date of food stored in a container, this is not always straightforward. The varying reaction rates of the food’s spoiling components, which are not always constant, pose a significant challenge. These rates can be linear or parabolic. Additionally, the storage temperature can vary, especially if the food is exported to different countries, further complicating the prediction process.
As we’ve discussed in previous sections, a high polarization resistance or the resistance added by the coating indicates a low corrosion of the can. This, in turn, translates to a longer shelf life for the food stored in it. However, it’s important to note that the resistance of the coating is not a static value. It is influenced by factors such as temperature and storage time. Therefore, to accurately predict the shelf life, it’s necessary to conduct measurements at various temperatures and storage times.
EIS, a nondestructive technique highly sensitive to interface changes, is a suitable method for investigating coatings for food cans.
Testing the Shelf Life:
First, cans are coated and packed as usual. They are tested after certain time periods, such as 1 day, 1 week, 1 month, 4 months, and 12 months.
If the product in the can is being conducted, the measurement can be performed on the product, which acts as an electrolyte. Otherwise, the product needs to be replaced with 0.5 M NaCl solution. Keep in mind that a fat or oil film on the can coating might act as an additional film, but strong detergents to remove the fat film may also change your coating.
The can is connected as the working electrode. The reference and counter electrodes are immersed in the can’s solution. Electrochemical Impedance Spectroscopy is performed, and the spectra for the different storage times are compared.
Coating Research in Food Industry
Coating, contamination storage, corrosion, counter electrode, detergent, disbonding, Electrochemical Impedance Spectroscopy (EIS), Electrochemistry, equivalent circuit, expiration date, food can, Food Industry, food storage containers, polarization resistance, shelf life, spoiling substance, working electrode
