This question, like most culinary questions, is a hot-button issue in the kitchen. There are those who say that you can and those who say absolutely no way can you cook acidic food in cast iron. The common counterargument is that the tomatoes will taste “metallic” after being cooked in cast iron. I know from personal experience that tomatoes can be cooked in cast iron. I often make my 4-hour spaghetti in a dutch oven and trust me, I’ve never had any complaints from the table!
Let’s start at the beginning. Why wouldn’t you be able to cook tomatoes in cast iron? Because they are acidic and acid can lift molecules from the cast iron and impart them into the food being prepared. This is true to a point, but the trace amounts of molecules are not harmful and generally are tasteless.
Professional kitchens have tested this theory and the general consensus is, that so long as the acidic food is cooked for short amounts of time, there is little risk that the cast iron will impart unwanted flavors into your dish. Of course, it also depends on how high the acidity level in the food is. For instance, America’s Test Kitchen tested this theory by cooking a very acidic sauce in cast iron and found that at 30 minutes of cook time, the food tasted off.
As mentioned earlier, I have been making spaghetti in a dutch oven for years without realizing that acidic foods were considered by most to be a no-go in cast iron. After some research, I discovered that how well seasoned a cast iron is making a big difference. The dutch oven I use is over 70 years old and, obviously, well seasoned. The oil used for seasoning polymerizes and adds a coat of protection to the cast iron which helps the metallic reaction from occurring.
The takeaway is that, yes you can cook tomatoes and other acidic food in a cast iron but it is best to wait until the cast iron has been well seasoned. Also, for highly acidic foods, keep the cooking time to 20 minutes or less. Since there are no two cast irons alike, it is recommended to test a small batch of acidic food in your cookware before you make the actual dish.
What about enameled cast iron?
Enameled cast iron is porcelain enamel which is a type of glass. Enamel, like glass, is resistant to acidic foods and presents no problem with cooking acidic food in them. An added advantage of cooking acidic foods in enamel is that enamel is easy to clean. The bottom line is, that although you can cook tomatoes in a well-seasoned cast iron skillet, it is a good idea to have an enamel cast iron on hand for higher acidic foods and longer cooking times.
Should You Reseason Your Cast Iron Pan After Cooking Tomatoes?
It is wise to reseason cast iron cookware after every use. The heat dries the excess water used to clean it, which prevents rusting, and the oil adds protective layers to the skillet. Plus the more a cast iron is seasoned, the more non-stick it becomes. You can forego the seasoning process after every use so long as you thoroughly dry it. However, you should always reseason a cast iron after cooking tomatoes.
The reason for this is that acidic food, like tomatoes, has a chemical reaction to iron. This reaction can loosen metallic molecules. Also, tomato acid can damage your seasoning. The chances are, you will never notice these changes. These reactions will be more noticeable on newer cast iron though. In order to avoid this, it is a good precaution to reseason your cast iron cookware after cooking tomatoes in it.
What is the Best Type of Pan to Cook Tomatoes In?
Overall, the best pan to cook tomatoes in is stainless steel because it is non-reactive or an enameled cast iron. These pans are non-reactive which makes them ideal for cooking acidic foods. Reactive pans such as aluminum or unseasoned cast iron cause a chemical reaction to the acid in the food and can cause a metallic taste in the food. Even though tomatoes can be cooked in regular cast iron with no issues, it is best to use a strictly non-reactive pan.