engleski

Corrosion behavior of tinplate cans in contact with tomato puree and protective (inhibiting) substances

The tin-iron alloy (FeSn2) is produced by diffusion of pure tin into the steel base during electrolytic process. When the alloy layer is not compact and continuous, the steel is exposed through the pores to aggressive food compounds and its corrosion is accelerated. Both, iron and tin, when in excess are toxic elements. Even in therapeutic doses iron may cause gastrointestinal side effects. Excess iron in primary and secondary hemochromatosis may lead to hepatic fibrosis, diabetes mellitus, and cardiac failure. Iron increases oxidation stress, which may also increase DNA damage and oxidative activation of precancerogens and support tumor cell growth. An upper safe level of iron is 25-50 mg/day. Tin poses an external as well as an internal health hazard associated with the increased likelihood of inducing cancer in bone and other organs and tissues in which it may be deposited. In this work the dissolution of iron and tin from tinplate can filled with tomato puree as acidic media (pH=4.34) with and without the presence of inhibiting substance (essential onion oil, EOO) or nitrate is analysed with AAS. Head-space gases (H2, O2, N2 and CO2) as indicators of corrosion process have been identified and analysed by GC and nitrates have been determined using HPLC. The results indicate that the addition of EOO in tomato puree prevents corrosion process even during 5 months of storage at 20 º ; C, while at higher temperature (36 º ; C) the presence of EOO accelerates the corrosion process. In cans with potassium nitrate added to the product, dissolution of tin starts after 30 (36 º ; C) and 60 (20 º ; C) days of storage as a consequence of nitrate action as corrosion accelerator. As EOO adds to the taste of canned tomato puree, its potential use as a corrosion inhibitor would be of interest.

tinplate cans; corrosion inhibition; essential onion oil

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