It’s commonplace to see the phrase “nonreactive saucepan” in recipe directions – like in this one for Cranberry Sauce (click for recipe) – but rarely does the recipe explain what that means or what the consequences are if you use a “reactive saucepan.”
First, the terminology. A “nonreactive” saucepan, pot, frying pan, etc, is one that doesn’t react with the food being cooked; problem foods typically feature ingredients that are acidic. By contrast, a “reactive” saucepan is one that reacts to these acidic foods. Acidic foods vary widely, and include things like tomatoes (tomato sauce, salsa), wine, cranberry sauce, pickling brine, lemon, rhubarb, etc. Look to your recipe for guidance on whether or not a nonreactive pot or pan is needed.
Stainless steel cookware is typically considered nonreactive. Cast iron pots with an enamel finish are also non-reactive, unless there are any chips or cracks in the enamel.
Aluminum is one of the most common types of reactive cookware. Non-enameled iron is also reactive, as is copper. While copper is often used in a pot’s construction, the cooking surface isn’t normally made with copper. If the part of the pot that comes into contact with food is copper, it qualifies as a reactive pan
Why does all of this matter? Because you don’t want your food to react with your cookware. When acidic foods react with the pot, this can both damage the pot and transfer metal material to your food.
While many home cooks use stainless steel pots and pans, recipes still list it in the off chance you’re using a saucepan made with something other than stainless steel.