Procedure optimization of type 304 and 420B stainless steels release in acetic acid

Stainless steel has always been considered suitable for food contact, even though it has been demonstrated that this material has the tendency to release metal ions when used in food contact applications. In this study, the testing procedure for metal release in simulated food contact proposed by the Italian Ministerial Decree 21.03.1973 highlighted some critical aspects that needed to be improved such as the surface finishing, solution composition and volume, and reproducibility. AISI 304 austenitic and AISI 420 type B martensitic stainless steels were chosen to optimize the parameters of test procedure for release of Chromium, Nickel and Manganese. The effects of the steel chemical composition, the material fabrication cycle and the testing method on metal release were evaluated. Considering the achieved results, a list of suggestions is proposed for the improvement of the Italian law.