Ham is pork that has been preserved through salting, smoking, or wet curing. It was traditionally made only from the hind leg of swine, and referred to that specific cut of pork. Ham is made around the world, including a number of highly coveted regional specialties, such as Westphalian ham and Jamón serrano. Technically a processed meat, "ham" may refer to a product which has been through mechanical re-forming.
The precise nature of meat termed "ham" is controlled in a number of areas, often by statute, including the United States and European Union. In addition, numerous ham products have specific geographical naming protection, such as Prosciutto di Parma and Prosciutto Toscano PDO in Europe, and Smithfield ham in the US.
The preserving of pork leg as ham has a long history, with Cato the Elder writing about the "salting of hams" in his De Agri Cultura tome around 160 BC.
There are claims that the Chinese were the first people to mention the production of cured ham. Larousse Gastronomique claims an origin from Gaul. It was certainly well established by the Roman period, as evidenced by an import trade from Gaul mentioned by Marcus Terentius Varro in his writings.
The modern word "ham" is derived from the Old English ham or hom meaning the hollow or bend of the knee, from a Germanic base where it meant "crooked". It began to refer to the cut of pork derived from the hind leg of a swine around the 15th century. Preservation methods include curing, smoking, and salting.
Because of the preservation process, ham is a compound foodstuff or ingredient, being made up of the original meat, as well as the remnants of the preserving agent(s), such as salt, but it is still recognised as a food in its own right.
In many countries the term is now protected by statute, with a specific definition. For instance, in the United States, the Code of Federal Regulations (CFR) says that "the word 'ham', without any prefix indicating the species of animal from which derived, shall be used in labeling only in connection with the hind legs of swine".
In addition to the main categories, some processing choices can affect legal labeling. For instance, in the United States, a "smoked" ham must have been smoked by hanging over burning wood chips in a smokehouse or an atomized spray of liquid smoke such that the product appearance is equivalent; a "hickory-smoked" ham must have been smoked using only hickory. However, injecting "smoke flavor" is not legal grounds for claiming the ham was "smoked"; these are labeled "smoke flavor added". Hams can only be labeled "honey-cured" if honey was at least 50% of the sweetener used, is at least 3% of the formula, and has a discernible effect on flavor. So-called "lean" and "extra lean" hams must adhere to maximum levels of fat and cholesterol per 100 grams of product.
Ham re-formed from smaller pieces into a larger block also has to be labeled in many jurisdictions.
Ham is produced by preserving and flavoring raw pork by salting, smoking, or wet curing. Besides salt, several ingredients may be used to obtain flavoring and preservation, from black pepper (e.g. Prosciutto Toscano PDO) to the precious saffron (e.g. the "Zafferano di San Gimignano PDO" in the esteemed Golden Ham).
Traditional dry cure hams may use only salt as the curative agent, such as with San Daniele or Parma hams, although this is comparatively rare. This process involves cleaning the raw meat, covering it in salt (for about one month for Parma ham) while it is gradually pressed – draining all the blood. In Tuscan Ham (Prosciutto Toscano PDO) different spices and herbs (from garlic to black pepper, from juniper to laurel) are added to salt during this step. Specific ingredients may be used to enhance flavour and taste during this step, e.g. pure saffron in the Golden Ham from San Gimignano (Italy). The hams are then washed and hung in a dark, temperature-regulated place until dry. It is then hung to air for another period of time.
The duration of the curing process varies by the type of ham, with Serrano ham curing in 9–12 months, Parma hams taking more than 12 months, and Iberian ham taking up to 2 years to reach the desired flavour characteristics. Some dry cured hams, such as the Jinhua ham, take approximately 8 to 10 months to complete.
Most modern dry cure hams also use nitrites (either sodium or potassium), which are added along with the salt, although following a similar methodology. The nitrites deliver a distinctive pink or red tinge to the meat, as well as imparting flavour. The amount and mixture of salt and nitrites used have an effect on the shrinkage of the meat.
Sodium nitrite is used because it prevents bacterial growth and, in a reaction with the meat's myoglobin, gives the product a desirable dark red color. Because of the toxicity of nitrite (the lethal dose of nitrite for humans is about 22 mg per kg body weight), some