The Chemistry Of Cast Iron Pans: What's In The Pan?

Cast iron pans are safe to use and have been used for hundreds of years. They are made of an alloy that is over 90% iron and do not contain lead or other heavy metals that are harmful to health. However, they can leach iron into food during the cooking process, so it is best to avoid using them frequently or for cooking acidic foods that require long cooking times, such as tomato sauce.

Cast iron pans can be seasoned to create a non-stick surface. This involves coating the pan with a thin layer of unsaturated oil, such as canola, flaxseed, grapeseed, or avocado oil, and heating it in an oven until a hard, polymerized fat coating forms. This coating is hydrophobic and prevents food from sticking to the pan. Properly seasoned cast iron pans are safe to use and can be a great addition to your kitchen.

The benefits of cast iron cookware

Cast iron cookware is a popular choice for many home cooks and professional chefs. Here are some of the benefits of using cast iron:

Durability

Cast iron is known for its durability and longevity. With proper care, cast iron cookware can last for generations. Many people still use cast-iron pans that have been passed down through their families. Cast iron is virtually indestructible and can be easily restored if mistreated.

Non-stick Coating

Cast iron can develop a natural non-stick coating over time, making it incredibly versatile and easy to clean. This coating, known as "seasoning," improves with use and can make cast iron just as non-stick as aluminium or stainless steel pans. The natural non-stick surface also makes cast iron ideal for minimalist cooks who want to downsize their pot and pan collection.

Heat Retention

Cast iron has excellent heat retention properties. Once a cast-iron pan is hot, it stays hot, making it ideal for high-heat applications like searing steak. The initial drop in temperature when adding food is much smaller than with other materials like stainless steel, allowing for higher heat and better browning.

Affordability

Cast iron cookware is often sold at affordable prices and, because it lasts a long time, can be considered a one-time investment. Cast iron is usually easy to find in thrift stores and second-hand shops, making it accessible to those on a budget.

Versatility

Cast iron comes in many shapes and sizes, including skillets, pots, griddles, cake pans, and pizza sheets. It can be used on any type of stovetop (gas, electric, or induction) and can also be placed directly into the oven or over an open flame like a campfire. Cast iron's versatility makes it suitable for a wide range of cooking techniques, including searing, sautéing, baking, and frying.

Health Benefits

Cast iron cookware can add a small amount of iron to your food, which may be beneficial for those with iron deficiency. However, the amount of iron transferred is minimal, and cooking acidic foods like tomatoes or citrus juices may strip the seasoning and increase iron leaching. Cast iron also lends itself to healthy, lower-calorie cooking methods that require less oil, such as poaching, braising, grilling, and quick broiling.

How to season a cast iron pan

Cast iron pans are a great, non-toxic, and safe alternative to non-stick pans. They are durable, affordable, and perfect for a variety of cooking techniques. Seasoning your cast iron pan will help to create a protective coating, preventing your pan from rusting and creating a natural, easy-release cooking surface. Here is a step-by-step guide on how to season your cast iron pan:

Step 1: Wash and Dry Your Pan

Give your cast iron pan a good scrub with warm, soapy water, and then dry it thoroughly. It is important to ensure that there is no remaining surface moisture, so consider placing the pan on a stovetop flame for a minute or two to drive off any lingering water.

Step 2: Rub with Oil

Once your pan is clean and dry, rub it all over, inside and out, including the handle, with cooking oil. It is recommended to use unsaturated cooking fats, such as vegetable, canola, corn, avocado, or flaxseed oil. Avoid using too much oil, as this can cause your pan to become sticky. The key is to rub the oil all over and then buff it thoroughly so that the pan no longer looks greasy. The pan should feel practically dry to the touch.

Step 3: Heat the Pan

Place the oiled pan in a preheated oven at a temperature between 350°F and 500°F for about 30 minutes to an hour. It is recommended to place the pan upside down and put a baking sheet or aluminum foil on the rack below to catch any oil drips. This step will polymerize the oil, forming a hard, plastic-like coating. You may notice some smoke during this process, so ensure your kitchen is well-ventilated.

Step 4: Cool the Pan

After the allotted time, remove the pan from the oven (remember, it's hot!) and turn off the oven. Allow the pan to cool down completely inside the oven before handling it.

Step 5: Repeat for an Unseasoned or Stripped Pan

If you are starting with a brand new pan or a pan that has had its seasoning stripped, you will need to repeat the above steps multiple times until a smooth finish develops. A well-seasoned cast iron pan will have a smooth, hard, and evenly colored finish.

Cast iron pans are generally considered safe and free from harmful chemicals. They are made of an alloy that is over 90% iron and do not contain lead or other heavy metals. However, some antique cast iron cookware or pieces with decorative high-temperature enamel finishes may contain lead. Additionally, some pre-seasoned cast iron pans may be coated with vegetable oil, which could contain undisclosed additives. It is always a good idea to check the manufacturer's information and ingredients list to ensure the safety of your cast iron pan.

How to clean cast iron pans

Cast iron pans are a safe and healthy alternative to non-stick pans, which can release toxic chemicals when heated. However, cast iron pans require special care to keep them in good condition. Here is a step-by-step guide on how to clean and care for your cast iron pan:

Step 1: Cleaning the Pan

• It is best to clean your cast iron pan while it is still hot, as stuck-on food can harden as it cools.
• Use hot water and a heavy-duty cast-iron scrubber to clean the pan. Do not use soap, as it can strip the seasoning from the pan.
• For stuck-on food, use a small amount of salt and a dry towel to help lift the food away. You can also try boiling a little water in the pan to loosen the residue.
• If there is still food stuck on the pan, use a nylon scrubbing brush, pan scraper, or wooden spatula to remove it. Rinse the pan under warm water, being careful not to soak the pan, as this can cause rust.

Step 2: Drying the Pan

Dry the pan thoroughly with a lint-free cloth or paper towel. You can also place the pan on the stove and turn the burner to high to ensure all the water is evaporated.

Step 3: Seasoning the Pan

• To season the pan, rub a very light layer of cooking oil onto the surface. Flaxseed oil, canola oil, avocado oil, and grapeseed oil are good options. Avoid using too much oil, as this can make the pan sticky.
• Use a paper towel to wipe the surface until no oil residue remains.
• Heat the pan on the stove until it is very hot.
• Place the pan upside down in the oven and bake at 350-500 degrees F for one hour. This helps the oil bond to the iron and creates a non-stick surface.
• Allow the pan to cool completely before using it again.

Additional Tips:

• If your cast iron pan has developed rust, you can remove it by scouring the pan with warm, soapy water and steel wool. Rinse and dry the pan thoroughly, then re-season it following the steps above.
• To store your cast iron pan, hang it on a strong hook or stack it with paper towels in between pans to protect the finish.
• Avoid using metal scrubbers or steel wool on your cast iron pan, as this can damage the surface.
• Do not put your cast iron pan in the dishwasher, as this can remove the seasoning and cause rust.
• Avoid cooking acidic foods, such as tomatoes or tomato sauce, in your cast iron pan, as this can strip the seasoning and increase the release of iron.

Foods to avoid cooking in cast iron

Cast iron pans are a favourite among chefs for their versatility. However, there are some foods that are better suited to other types of cookware. Here are some foods to avoid cooking in a cast-iron pan:

• Acidic foods: Acidic foods like tomatoes, citrus fruits, vinegar, and wine can damage the seasoning or non-stick coating of your cast iron pan. They can also cause the pan to leach small amounts of metal into your food, resulting in an off-taste and potentially harming your health. Additionally, the acid can cause the food to take on a metallic flavour.
• Delicate fish: Flaky white fish like flounder or tilapia can fall apart and not flip well when cooked in cast iron. Even heartier fish like salmon can be difficult to flip due to the skin sticking to the pan. It is better to cook these types of fish in a non-stick or stainless-steel pan.
• Sticky foods: Foods like eggs, pancakes, and fried rice can stick to a cast iron pan, especially if it is new and not yet well-seasoned. This can result in over-browning and make the pan more difficult to clean. It is better to wait until the pan is well-seasoned before attempting these types of dishes.
• Aromatic foods: Foods like garlic, peppers, and stinky cheeses can leave strong aromas in your cast iron pan that can transfer to the next few dishes you cook. While you can remove the smell by heating the pan in the oven, it is best to avoid cooking foods that would be ruined by lingering aromas.
• Wine-braised meats: Similar to acidic foods, the acid in wine can leach small amounts of metal into your food and affect the taste. It is better to use a different type of pan for wine-braised meats.

The safety of cast iron cookware

Cast iron cookware is generally considered safe for most people. However, there are a few things to keep in mind when using cast iron pans.

The benefits of cast iron cookware

Cast iron is a great material for cookware because it is a good conductor of heat and can maintain high temperatures for long periods of time, promoting even cooking. It is also versatile and gets better with time.

The concerns with cast iron cookware

One concern with cast iron cookware is that it can transfer a small amount of iron to food, which could be harmful to people with certain health conditions, such as hemochromatosis, which causes the body to absorb too much iron. Additionally, cooking acidic foods in cast iron pans can strip the seasoning and increase the amount of iron leached into food.

Another concern is that cast iron pans can sustain high heat, which may produce chemicals known as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which are linked to an increased risk of cancer. However, this is mainly only a concern when grilling, as cast iron pans used indoors are unlikely to reach high enough temperatures to produce these chemicals.

Tips for safe use of cast iron cookware

• Avoid using cast iron cookware if you have hemochromatosis or another condition that affects your iron levels.
• Avoid cooking acidic foods, such as tomatoes or citrus, in cast iron pans, as these can strip the seasoning and increase iron leaching.
• Avoid cooking at extremely high temperatures, especially when grilling, as this can produce HCAs and PAHs.
• Always properly season your cast iron cookware to create a protective layer that prevents food from sticking and rusting.
• Clean your cast iron cookware regularly and dry it thoroughly before storing to prevent rust.

How to season cast iron cookware

To season cast iron cookware, first, make sure it is thoroughly cleaned and dried. Then, apply a thin layer of oil, such as avocado oil, flaxseed oil, or grapeseed oil, and heat the pan in the oven at a high temperature (around 450-500°F) until the oil forms a hard surface. Repeat this process multiple times to create a strong, non-stick coating.

Frequently asked questions