The metal packaging is ideal for storing canned food especially tinplate. Due to the acid nature of the canning solution, the interaction of the food with the metal packaging determines its shelf life, as there may be corrosion, which occurs when there is dissolution of the metals present in the packaging. The layer of varnish of these packages aims to minimize interactions of the metals with the food thus increasing the expiration with the storage time, as well as to evaluate the role of the lacquer layer (varnish) in reducing the corrosion rate. Firstly, the pH, conductivity, °Brix, viscosity, density and NaCl concentration of the canning solution corn were determined and the values were 6.05; 35.8 mS/cm; 6%; 1.26 cP; 1.024 g/mL; 9000 ppm, respectively. The metal can microstructural characterization was made by optical microscopy (OM) and X-ray diffraction (XRD). The linear polarization technique was used to identify the corrosion rate (Tc) of cans. The Tc increased significantly when the varnish was removed, and the lid was the region of the can that showed the highest corrosion rate, reaching 0.760 mm/year in the absence of varnish which reduced the corrosion by approximately 25 percent. The Fe contents on the third day of analysis showed values within the Brazilian legislation. The increase of the NaCl concentration and the pH medium directly influence the increase of the corrosion rate.