A non-reactive bowl is a bowl made of a substance that won’t react chemically with the foods that are placed in it. Reactive bowls are often made of metal, like copper, cast iron, or aluminum, or plastics that stain easily. When a cook adds any high acid foods to these bowls — like lemon juice, most citrus fruits, or tomato sauce — they may actually react with the metal in the bowls and impart a metallic taste to the foods. If a cook needs a metal bowl that will not react, he or she will always want to look for stainless steel, since it tends to resist reaction with high acid foods.
People may note that the bowl that comes with a stand mixer is usually a non-reactive metal bowl, made of stainless steel. Consumers shouldn't bother with a stand mixer that has a more cheaply made aluminum bowl, since this will limit what they can make with it. Those who prefer plastic bowls should look for the type that boasts “non-staining” abilities, or try silicone bowls, since they won’t react. Virtually any glass or ceramic bowl is non-reactive and won’t stain or give a metallic taste to acidic ingredients. Cooks should consider glass or ceramic bowls for fruit salad, anything containing lemon juice, and anything containing tomato sauce.
Under some circumstances, a non-reactive bowl will not serve you as well as a reactive bowl — for instance, many chefs prefer to use copper bowls to whip egg whites. The egg whites react with copper and not only whip faster but are also more firm and stable. Note that if a copper bowl is advertised as non-reactive, it usually has a stainless steel or other coating that will prevent this reaction.
In general, cooks can use any type of bowl to make most cakes and cookies. The time that the ingredients spend in the bowl is generally so short that they won’t have time to react with metals. Glass, ceramic, stainless steel, or any non-reactive plastic bowl is still a better choice, however, especially if the ingredients will sit for any length of time. Cooks should always choose a non-reactive bowl for high acid ingredients, and never mix something like a vinaigrette in an aluminum bowl.
Many recipes call for this type of bowl, but that doesn't mean that home cooks need to buy expensive new bowls or ones that are heavily advertised as non-reactive. Any glass or ceramic bowl tends to work just fine, and many inexpensive bowls made of these materials are available. Shoppers who are looking for new cookware that is non-reactive should choose stainless steel over cast iron, copper, or aluminum if they plan to cook acidic recipes. Furthermore, cooks shouldn't forget to keep a reactive copper bowl on hand if they like to make souffles, mousses, angel food cake, or lemon meringue pie.