Pork labelled "seasoned" is pork that has been processed using a brine (salt, water, sodium phosphate) solution, in order to create a product that retains moisture even when overcooked. Other meats and poultry, such as beef and chicken, can also be "seasoned".
Since many pork cuts are very low in fat, they can tend to become dry and perceived as tough after cooking. Seasoned pork allows for a more tender and juicy product even if overcooked or held warm for periods of time.
The addition of salt, water and sodium phosphate to solid meat or poultry allows the product to retain moisture throughout cooking: the sodium phosphate binds the water molecules to the protein in the meat, and the salt acts as an enabler in the process.
Seasoned meats and poultry are not flavoured or spiced, so do not have a taste noticeably different than unseasoned products.
Not all pork sold at retail is seasoned, however pork that is seasoned must be labeled as such. Seasoned pork must also be labeled with a list of ingredients as well as a declaration of percent meat protein. Pork that has not been seasoned (i.e. a single ingredient meat product) usually does not have an ingredient list or a Nutrition Facts table.
A Nutrition Facts table is required on meat and poultry with added phosphates and/or water whether packaged at retail or packaged at the manufacturer. The amount of sodium for a seasoned product will be higher than for an unseasoned product. For example, an average (100 g/3 oz) seasoned centre-cut pork loin chop has about 300 mg of sodium (this figure varies according to cut and manufacturer). To put this in perspective, the recommended upper tolerable limit for healthy adults is 2300 mg of sodium per day (approximately 1 tsp of salt)*. The amount of sodium recommended for healthy Canadians aged 9 - 50 is 1500 mg per day, and 1300 mg per day for Canadians age 51-70. People on sodium-restricted diets should follow their doctor's advice, and carefully read labels in all cases.
*Institute of Medicine of the National Academies. Dietary Reference Intakes: The essential guide to nutrient requirements. The National Academies Press, Washington DC, 2006