Wrought Aluminium Alloy Corrosion Propensity in Domestic Food Cooking Environment

The study on corrosion behaviour of wrought aluminium alloy in domestic food cooking conditions has been examined using the gravimetric approach. Flat cold rolled and annealed sheets were subjected to solutions of Capsicum annuum, L. esculentum, Allium cepa, and their blend under three conditions, namely, heating and cooling in still air, heating and cooling in refrigerator, and leaving some in open still atmosphere. Results show that corrosion occurred within the test period (288 hours) in the test environments. There was severe degradation within the first 70 hours of test when coupons were heated and cooled while unheated coupon showed low corrosion propensity. Microstructural analysis show the presence of corrosion pits on coupon surface with second phase particles sandwiched in α-aluminium matrix. Immersed coupon in the blend media show higher number of pits on the surface. Rapid corrosion of wrought aluminium alloy in Capsicum annuum, L. esculentum and Allium cepa media is attributed to the presence of corrosion aggressive elements such as allicin, diallyl-disulphide, and allyl-propyl disulphide present in the corrosion media. 1. Introduction Aluminium alloy cookware, containers, cooking utensil, and aluminium beverage cans contribute substantially to the consumption load of aluminium [1, 2]. Deep drawn aluminium utensils are widely used as domestic cooking vessel in the third world countries. Such utensils are subjected to several heating cycles during their service lives. In aggressive cooking environment the aluminium is very prone to localized attack and progressive failure that occurs due to pitting which shortens the service life span of these cooking utensils [3, 4]. A study conducted at the University of Cincinnati Medical Centre [5] reveal that acid forming foods dissolve aluminium more rapidly and that tomatoes cooked in an aluminium pot had 2 to 4 milligram aluminium content in serving. The corrosion products particle is leached from the utensil into the foods being cooked. It has been shown that healthy human body can handle up to twenty milligrams of aluminium ingestion per day [1], this absorbed aluminium is eliminated through the kidney in form of urine and unabsorbed aluminium is excreted in the faeces [1, 6]. Unfortunately, the activity of the kidney decreases with age [3, 6]. At 65 years and above, the ability of the kidney to eliminate aluminium diminishes [3], resulting in the accumulation of these particles in the body. These particles are distributed mainly in bone, liver, testes, kidneys, and brain [1, 6]. Numerous studies