A linear sweep voltammetric (LSV) approach
is proposed for achieving rapid information on metal
release from tinned containers into preserved vegetables.
Chopped tomato and pea preserves were chosen as prototypes
for acid and nearly neutral canned food, respectively.
Metal release in these vegetables tinned into both bare and
lacquered containers was compared with that found in
synthetic samples containing some organic complexing
agents (acetic, ascorbic, citric, malic, oxalic, pyroglutamic
acids) present in the vegetables considered, thus showing
that some of these components affected markedly the metal
release in bare cans. These ligands were concomitantly
found to also affect LSV profiles recorded in parallel at Sn
and Fe electrodes in synthetic samples, causing the starting
potential for their oxidation to be lower, the higher the
ligand activity of the species considered. The data indicated
that metal release and starting potentials for metal
discharge are strictly related, so that LSV is able to provide
rapid and useful information on the nature of the protective
effect (electrochemical or physical) of tin on the steel
underlayer, as well as on the extent of Sn and Fe release.
