No abstract

As part of a coordinated research program on internal can corrosion, the action of nitrates on tinplate was studied in model systems simulating foods of varying acidities. Detinning rates were measured in citrate buffered nitrate solutions ranging in pH from 3.0-7.0.At pH values less than about 5.2-5.5 the detinning is extremely rapid, with slower rates at higher pH values. Nitrateconcentrations of 125 ppm in pH 4 buffers completely detinned wns in about 2 months at ambient temperatures. Ammonia is the principal nitrate reduction product in the pH range of acid products.Nitrous oxide is also produced and acts as an effective detinner at pH 4 and 5. Nitrogen may also be produced at pH 5.