Aluminum is a popular metal in cookware and bakeware because it's lightweight and good at conducting heat. One downside to aluminum is its softness. To give it more strength, aluminum is often alloyed with other metals, such as magnesium, copper or bronze. An additional problem with aluminum is that it reacts with certain foods and can change their flavor.
Tomato sauce and other tomato products react with aluminum because of their acidity, and acids don't mix well with aluminum. Highly acidic foods cause oxidation, which can darken the aluminum pan and alter the taste of the food. You can avoid this oxidation problem if you choose cookware that has aluminum on the inside with an outer coating of stainless steel. If you want to spend a little more money, buy anodized aluminum cookware.
Fruits can cause oxidation because of their acid content; for example, apples contain malic acid, and citrus fruits are high in citric acid. Both can react with uncoated aluminum.
Avoid cooking several types of vegetables in aluminum. Rhubarb, sauerkraut, asparagus and artichokes are some of the veggies may react with aluminum. Again, the acid in these foods reacts with the aluminum.
If you like cooking with vinegar, you might want to consider cooking in something other than uncoated aluminum. The amount of acetic acid in vinegars can vary, but it's especially high in pickling vinegars.
If you enjoy scrambling eggs or flipping omelets, an aluminum pan may not be your best choice. Egg yolks may cause oxidation problems, and the minute amounts of aluminum released into the eggs may give them an off taste.
Foods high in salt may react with aluminum. In fact, makers of aluminum cookware and bakeware warn against storing salty foods in uncoated aluminum products. The salt can cause pitting of the aluminum surface over time. Highly acidic foods can lead to pitting too.