In recent years, cast iron pots seem to be making a comeback, and with just a quick search online, you can find various benefits of using cast iron pots. For example, claims like "cooking in a cast iron pot can supplement iron intake" and "cast iron pots do not require chemical coatings to prevent sticking, making them safer to use." There's also a strong advocacy for cast iron pots, with some believing that "in the past, a cast iron pot could last for decades, but nowadays, pots only last a few years; it has to be a cast iron pot."
However, a search online reveals that cast iron pots come in various types: cast iron, raw iron, seasoned iron, and wrought iron. Prices also vary widely, ranging from tens of CNY to hundreds or even thousands. So, what are the differences between these cast iron pots, and are the more expensive ones really better than the cheaper ones?
The picture is taken from the internet.
When it comes to the price of iron pots, it's not necessarily true that the more expensive, the better. The primary factors affecting the price are the raw materials and craftsmanship.
Let's start with the answer: There are mainly two types of iron pots on the market, namely cast iron pots and wrought iron pots, and neither type is inherently superior or inferior. The different prices of iron pots are mainly due to differences in manufacturing processes, brand, and cultural influence.
Cast iron pots are made of iron with a relatively high carbon content, also known as pig iron. These pots are often cast by pouring molten iron directly into molds. Many heavy pots used on rural stoves are cast iron pots.
Wrought iron, on the other hand, contains relatively low carbon content. Because this type of iron used to be forged from pig iron in ancient times, it is also called wrought iron or forged iron. Fine iron also belongs to this category. Common examples include pans from Zhangqiu, which fall into this category.
In fact, just looking at the prices of these two types of pots, you'll find that there's no absolute superiority or inferiority between cast iron pots and wrought iron pots.
For example, cast iron pots are relatively thick and heavy, so they take longer to heat up, but they also cool down slower than wrought iron pots, thus providing better insulation.
Wrought iron pots are generally thinner and lighter than cast iron pots, heat up faster, and are more suitable for stir-frying. Also, it's easier to lift a ladle in a wrought iron pot compared to a cast iron one.
However, there may be differences within the same type of iron pot. For instance, even among cast iron pots, the raw materials used for pouring, the casting process, and whether the manufacturer pre-seasoned the pot can all affect the price.
Furthermore, the industry standard for cast iron pots (QB/T 3648-1999) also specifies requirements for insulation, impact resistance, and explosion resistance. However, since this is a recommended standard, not all cast iron pots may comply, so it's something to consider when making a purchase.
It's important to note that because cast iron raw materials may contain more impurities, it's essential to check for a quality inspection certificate when purchasing cast iron pots to ensure safety.
Similarly, with wrought iron pots, the materials used for forging, the forging process, and whether the pot has been blued or subjected to other treatments can all affect the price.
Although the price of pots can be influenced by many factors, if some pots are sold at a high price under the guise of the following two names, you should be cautious.
Hemoglobin containing iron, image source: Wikipedia.
We have a higher absorption rate of heme iron, ranging from 15% to 35%. Foods like duck blood, pig blood, and red meat, as well as iron found in animal livers, primarily belong to this category.
On the other hand, non-heme iron has a lower absorption rate. For instance, some iron supplements contain ferrous sulfate, which falls under non-heme iron, with an absorption rate of only 5% to 10%. Many people believe that foods like red dates and spinach are good sources of iron, but they also contain non-heme iron, making their iron supplementation less effective compared to animal blood.
The iron scraped off from cooking pans is either iron powder or trivalent iron formed on the surface of iron pans after oxidation with air, both of which have low absorption and utilization rates. For example, research has shown that the human body absorbs only about 1.8% to 3.6% of iron powder (compared to 36% for ferrous sulfate). Therefore, using iron pans to supplement iron would yield very poor results.
To put this into perspective, let's do a little thought experiment. If we were to rely on iron pans for iron supplementation, how many iron pans would a person need to consume in a year?
According to the "Chinese Residents' Dietary Guidelines (2016)" and the "Chinese Residents' Dietary Reference Intakes for Nutrients (Part 3: Trace Elements)" (WS/T 578.3—2017), the recommended daily intake of iron for adult males is 12 mg, and for females, it's 20 mg. Considering a family of three, they would need to supplement 45 mg of iron daily.
If we calculate based on a 3% absorption rate, approximately 1500 milligrams (1.5 grams) of iron pan scraping would be needed per day to meet the requirement. So, in a year, roughly 547 grams of iron pans would be required.
In other words, each year, the weight of iron pans would decrease by more than one pound. Even if iron pans provided only half of the daily iron requirement, they would still lose half a pound per year. Additionally, the iron content in the meat we consume is not negligible, so eating meat regularly can meet our basic iron needs.
Therefore, the idea of relying on iron pans for iron supplementation is not very reliable. If a seller markets iron pans at a high price under the guise of iron supplementation, one should be even more cautious. Instead of spending hundreds or thousands of CNY on an "iron-supplementing iron pan," it's better to consume more foods like duck blood, pig liver, and clams.
Between water and the surface of the pan, there are gaps, as illustrated by Wikipedia. By leveraging the Leidenfrost effect, any pan can achieve a non-stick effect. For instance, when frying an egg, simply preheat the pan to a temperature well above the boiling point of water (e.g., up to 200 degrees Celsius). Once the egg is cracked into the pan, the moisture in the egg will trigger the Leidenfrost effect, creating an "air cushion" between the egg and the bottom of the pan. This principle indeed facilitates a non-stick cooking process.However, it's important to note that this characteristic is not exclusive to cast iron pans; all types of pans, including aluminum, stainless steel, and non-stick pans, can achieve this effect.
But when frying fish or meat, the Leidenfrost effect might not hold up because the "steam film" generated may not be strong enough to support the food, leading to sticking.
Thus, while it's true that cast iron pans can achieve a non-coating anti-stick capability, the physical non-stick feature of cast iron pans still requires the use of oil.
In essence, the difference in craftsmanship between a budget cast iron pan and a more expensive one does exist, along with some branding and cultural prestige, such as "Intangible Cultural Heritage iron pans." As long as it's within your budget, purchasing a good-looking, handmade cast iron pan is perfectly reasonable. Just don't be swayed by marketing slogans about "excellent iron supplementation" or "physical non-stick properties."
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Planned and Produced by: Author | Xiao Wei, Science Popularization Creator Reviewed by | Ji Yang, Researcher at the Institute of Semiconductors, Chinese Academy of Sciences Planning | Zhong Yanping Editor | Zhong Yanping Proofread by | Xu Lai, Lin Lin
