engleski

Corrosion inhibition with different protective layers in tinplate cans for food preserving

BACKGROUND: Nowadays the use of natural corrosion inhibitors is preferred and quite a number of papers are reported in recent years. In this work the influence of essential onion oil (EOO) on protection of tinplates was compared with dioctyl sebacate oil (DOS) and epoxyphenolic lacquers, frequently used in food canning industry. RESULTS: When EOO as protective layer instead of DOS oil was used, tinplates porosity measured electrochemically (4.5-10.5 μA cm-2 and 12.7-38.7 μA cm-2, respectively) and iron coating mass calculated from AAS data (1.3-1.8 mg m-2 and 2.4-4.2, respectively) was much lower indicating better corrosion protection. The efficiency of epoxyphenolic lacquer (double coating) was only 10 % higher then one obtained for tinplates with EOO. At higher storing temperature (36 °C) the addition of EOO to canned tomato purée enhanced the formation of hydrogen with time. The increasing volume fraction of H2 (from 34.0 to 90.9 % for cans without nitrates, and from 33.8 to 89.2 % for cans with nitrates) is an indicator that corrosion process takes place. CONCLUSION: As the use of EOO improves the protection of tinplate compared with DOS oil, and is almost as effective as epoxyphenolic lacquer, the addition of EOO can be recommended due to lower cost of canned food production and enhanced organoleptic properties, but the storage temperature has to be lower then 36 °C.

essential onion oil ; tinplate ; porosity ; headspace gases ; canned tomato purée

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