Foodstuffs corrosive effects

The corrosive effects to be considered (mainly simple corrosion of metals) are, as would be expected from the edible nature of foodstuffs which are not excessively either acidic or basic but which may contain sulphur, less severe than those often encountered with inedible materials containing reactive substances. The importance of corrosive efiects where foodstuffs are concerned lies not so much in the action of the foodstuffs on the metal involved as in the resultant metal contamination of the foodstuff itself, which may give rise to off-flavours, in the acceleration of other undesirable changes (by the Maillard reaction for example), and in the possible formation of toxic metallic salts. Metal ions generally have threshold values of content for incipient taste effect in different liquid foodstuffs. Except in the case of the manufacture of fruit juices and pickles, process plant failure through corrosion must be rare. Nevertheless all foodstuffs, particularly liquid ones, should be regarded as potentially corrosive and capable of metal pick-up which may be undesirable. 

Application of paint to steel surfaces has the primary purpose of preventing corrosion but can also provide decoration or other specialised effects, e.g. non-slip, anti-condensation, high or low reflectance, etc. Other specialised purposes such as the internal coating of tanks to hold a wide range of liquids, e.g. water, petroleum fuels, foodstuffs, chemicals, etc., may also be fulfilled. 

Corrosion of glass by water and aqueous solutions is of primary significance. Small amounts of decomposition products which have dissolved may have a harmful effect, even though the appearance and properties of the glass proper have remained unchanged (c.g. container glass for foodstuffs, liquid pharmaceuticals, injection solutions, etc.). 

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