Right here is how oil and warmth can kind a sturdy coating.
Picture Credit score: Jack Kennard, Flickr
Ahh, forged iron pans. Love ‘em or hate ‘em, they’ve been round for tons of of years. With correct upkeep, they’ll final lengthy sufficient to change into household heirlooms. A cornerstone of this pan’s repairs is seasoning, the method of baking oil onto the pan. Opposite to the identify, you received’t want salt and pepper, however fats.
To season, you warmth the pan lined in fats to scalding temperatures in an oven. What’s left behind is a considerably nonstick floor that not solely helps with cooking however protects the pan from rust.
You need to use the fats of your selection, however one factor to bear in mind is the smoke level, the temperature at which it begins to smoke. That temperature varies from oil to grease. For instance, virgin avocado oil has a smoke level of 520 F, however coconut oil smokes at simply 350 F. As quickly as that temperature is reached, the seasoning course of begins.
There are a number of hypotheses about what’s taking place on the molecular degree inside that scorching oven. The predominant one is that the oil is polymerizing. Fat are made up of various fatty acids, like saturated and unsaturated. When heated, these acids break down into smaller molecules referred to as monomers. And when monomers be a part of collectively, they kind bigger molecules referred to as polymers. When this becoming a member of occurs again and again in an iron skillet, the polymers kind a protecting layer that retains water at bay.
A bunch of researchers from Chongqing College studied this phenomenon within the context of one other forged iron cooking instrument: the wok. Woks, primarily utilized in Chinese language-style delicacies, are often round-bottomed. The staff hypothesized that the slick floor fashioned throughout seasoning is due extra to the iron than the oil. To check their speculation, the researchers coated a wok with beef tallow and heated it up. Because the temperature elevated, the fats began to cut back. And the scientists, utilizing X-ray expertise, began to see oxygen molecules sneaking into the locations the place iron was current. With this sudden visitor, iron atoms needed to shuffle round to create space, creating small lumps alongside the floor. The ultimate product is what the staff referred to as “iron nanoballs.”
They level out that these nanoballs didn’t make the wok utterly nonstick, however reasonably made the floor conditionally hydrophobic. That implies that it repels water when there isn’t a lot round, however will get moist when there’s loads of it. The research authors declare this property turns out to be useful throughout cooking, as a result of if the pans are utterly nonstick, the fats will lump collectively, inflicting uneven cooking. If the floor can get moist, it creates an excellent layer, and the meals can cook dinner evenly because the water evaporates, creating much less charring.
