Reduction of tin coating weight of aluminum-pigmented lacquered tinplate cans containing tuna in olive oil

摘要

To preserve in metal cans sulphur-containing food products such as meat, fish, crustaceans, eggs, milk, legumes, onions, cabbages, maiz, mushrooms, cans must be used having E2.8 fin infernal coatings (2.8 g Sn per m~2) and a further protection consisting of an organic coating. At present, however, canmakers tend to use tinplate with a lower tin coating weight in order to reduce costs and to rationalize storage management. Owing to their little aggressiveness to the container, sulphur-containing products are well suited for this type of operation. The objective of this work is to evaluate the possibility of using a tinplate with a low tin coating (1.4 g/m~2) as a package for a sulphur-containing product. To this end, the behaviour was studied of tuna in oil, packed in cans of E1.4 and E2.8 tinplate, as a reference (pack test). The cans were stored at 37 deg C for 6 months, during which time they were periodically examined for degree of vacuum, internal-surface morphology, pH and iron and tin contents. Additionally, electrochemical impedance measurements with a cystein model solution were made. As a conclusion, the possibility was considered of using low tin coating cans for packing tuna in oil.