Corrosion behaviour of tinplate cans in contact with tomato purée and protective (inhibiting) substances

Abstract

The dissolution of iron and tin from tinplate cans filled with tomato purée (pH 4.34) and dioctyl sebacate oil (DOS), essential onion oil (EOO) or potassium nitrate was studied using atomic absorption spectroscopy (AAS), while nitrate was determined using high-performance liquid chromatography (HPLC). The maximum values found in cans were up to 284 mg kg(-1) for tin and 513 mg kg(-1) for iron at elevated storage temperature. Results indicated that the addition of EOO to tomato purée prevents the corrosion process in the case of tin, where concentrations were lowered from 223 to 28 mg kg(-1) for cans with DOS oil and EOO at 20 degrees C, respectively (inhibition rate of 87%). On the other hand, the presence of EOO enhanced the corrosion process for iron increasing the concentration from 15 to 46 mg kg(-1) during 7 months of storage, although this value did not exceed maximum permitted value (50 mg kg(-1)). In cans with tomato purée and potassium nitrate, dissolution of tin started after 30 (36 degrees C) and 60 (20 degrees C) days of storage as a consequence of nitrate action, which act as a corrosion accelerator. Since the addition of EOO improves the taste of canned tomato purée, its potential use as a corrosion inhibitor would be of interest.

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

“…The results point out that in the canned samples with EOO at higher temperature (BN 0.1g36 and BSN 0.1g36) pitting type of corrosion occurred (anodic oxidation of Fe and development of H 2 ) as a result of EOO adsorption probably through sulfur atoms on the tinplate surface. The mass fractions of iron in these samples are extremely high; from 29.5 to 498.4 mg kg −1 for BN 0.1g36 and from 25.9 to 513 mg kg −1 for BSN 0.1g36 28. The values obtained exceed the maximally permitted limit3 of 50 mg kg −1 already after 30 days of storage and as such indicate a serious corrosion problem, which was not evident after the visual inspection of inner part of the empty cans, covered with a uniform violet film.…”

“…This study also confirmed that cans from two different groups (with and without nitrates) behave identically. Addition of nitrates had no influence on the production of H 2 , but it accelerates the dissolution of tin 28. During storage, the nitrates are reduced through a number of intermediates to ammonia and act as corrosion accelerators.…”

“…The acid medium of canned tomato purée (pH = 4.34) is a good substrate for tin oxidation in the Sn/NO 3 − system. When EOO is added to the tomato purée (BN 0.1g, BSN 0.1g) the dissolution of tin is strongly inhibited,28 due to the formation of a protective insoluble film on the metallic surface. Obviously, the film formed has a dual role; the dissolution of tin is inhibited, while at higher temperature iron dissolution from steel base is accelerated.…”

Effect of electro‐activated brine solution on the migration of metallic ions from the cans to the product in sterilized canned sweet corn

“…In order to avoid the tin and iron contamination, lacquers or different kinds of corrosion inhibitors can be used in order to protect the surface of the container (Nincˇevicˇ Grassino et al. ). Although corrosion can form under the layer of lacquer due to a variety of reasons such as improper uniform coating, damaged layer during manufacturing, and packaging or the influence of other physical or chemical factors (Platonova ).…”

Development of a Paste‐type Certified Reference Material of Tomato for Elemental Analysis: Certification and Long‐term Stability Study

“…Containers for canning are usually made of tin (Sn)‐plated steel because Sn has low toxicity and high corrosion resistance. However, acidic foods like tomato paste can result in elevating the rate of dissolution of Sn . Human exposure to Sn occurs mainly through dietary intake of foods from tin‐plated cans .…”