Ham Starts as a Leg of Pork That Is Cured, Not Just Cooked
In the United States, the food-safety agency of the Department of Agriculture describes ham as "the cured leg of pork." An uncured leg of pork is called fresh ham, and it has to be cooked like any other roast [2]. The same agency describes curing as treating the meat with salt, nitrate or nitrite, and sometimes sugar and seasonings [2]. (Nitrite and nitrate are salts that contain nitrogen. They are used in very small amounts.)
After curing, a ham can be smoked, cooked, or both. Many hams are sold ready to eat, which means you can eat them straight from the package. The agency lists cooked ham and prosciutto as examples [2]. Prosciutto is the Italian dry-cured ham, and it is the same kind of product that shops in Japan sell under the name nama hamu, "raw ham." "Raw" here is a little misleading. It is salted and dried for a long time rather than cooked in hot water or steam, which is why it is different from sandwich ham.
Japanese manufacturers describe a typical cooked-ham line as trimming, curing, packing, smoking (some hams skip this), cooking in hot water or steam until the middle is hot, then cooling and packaging. That order comes from one company's description, so other makers may do it differently. Why go to the trouble of curing before cooking? The next two sections give the reasons.
Why Curing Comes Before Cooking: Keeping the Meat Safe and Tasty
Extension specialists at Penn State say that meat is cured for three main reasons: preservation, flavor, and color [3]. Salt is one of the most effective tools for preserving meat. They note that salt holds back the growth of some bacteria, and that Salmonella can be slowed by concentrations of salt as low as about 3 percent [3].
The nitrite has its own job. The same source says nitrite works against Clostridium botulinum, the bacterium that makes the toxin that causes botulism, and keeps it from growing and making that toxin [3]. Nitrite is used at very low levels [3].
Salt slows bacteria but does not wipe them out, which is why ham does not rely on one method alone. Salting, heating the middle of the meat all the way through, and keeping it cold afterward are layered together. Putting the steps together this way is our own reading of how they fit; the sources above describe the steps themselves.
What Makes Cooked Ham Pink When Other Cooked Pork Is Gray?
The same Penn State page says that nitrate or nitrite is what develops the stable red color of cured meat [3]. The common textbook picture is this: nitrite turns into a gas called nitric oxide, nitric oxide attaches to heme (the iron-holding part of the red protein in muscle), and the resulting nitrosyl–heme complex stays red-pink even when heated. For a long time, this complex was thought to be the main pigment of cooked ham [1].
So, in short, the pink comes from curing. Without it, the meat turns gray-brown in the pot like a pork roast. In one 2022 experiment, ham made without nitrite or a replacement did not turn red [1].
But there was a surprise: ham made without nitrite, using a plant extract instead, also turned red [1]. If the nitrosyl–heme complex is not the only pigment, what else is in there? The next section looks at one team's answer.
Scientists Still Disagree About What the Pink Pigment Is
In 2022, a group of researchers in Spain published a study in the journal Foods. They made hams with nitrite, hams with a plant (polyphenol) extract instead of nitrite, and a control ham with neither. The nitrite-free hams with the plant extract turned red too, and their light-absorption patterns matched the nitrite-cured hams. The control ham, with neither, did not turn red [1].
When they looked at the pigments in detail, they found several related molecules called protoporphyrins, including one with zinc in it, in all of the hams. They concluded that a mixture of protoporphyrins contributes to the color of cooked ham, not the nitrosyl–heme complex alone [1].
It is worth being careful here. The authors say the test used for decades cannot show that nitrosyl–heme is the only red pigment, which is a challenge to a measuring method rather than a flat denial of the textbook picture [1]. The study also used a small number of hams, so its findings are preliminary [1]. A careful summary is that curing makes the pink, and exactly which molecules make it is still being worked out.
How to Read a Ham Label and Spot the Differences Yourself
With an adult, look at a package of ham. Does the label say "ham," "ham with natural juices," or "ham, water added"? In the United States, added water is allowed in a product labeled "Ham," and "Ham – water added" has to meet a set protein level with a specified amount of added solution [2]. Then check the ingredient list: is a curing ingredient listed, and in what order do the ingredients appear? Some packages say "no nitrite added." The sources we read do not explain how those products are made or labeled, so that is a good thing to look up yourself.
If you can compare a cooked ham with a ready-to-eat dry-cured ham such as prosciutto, notice the difference in texture and saltiness. Wash your hands first, keep ham cold, and follow the date on the package.
The pink-pigment question is open. If you are curious, the 2022 paper is free to read online, and its authors explain their experiments in plain steps.