Parmesan is a less-expensive, lower quality substitute for Parmigiano-Reggiano.
Technically, the difference between Parmesan and Parmigiano-Reggiano is that cheese can only be called Parmigiano-Reggiano if it is produced under a specific set of standards in the Emilia-Romagna region of Italy. Cheese produced in a similar manner to Parmigiano-Reggiano in the U.S. is called Parmesan and is often used as a substitute. However, since Parmesan is produced in a different region and under less stringent guidelines, it has a different flavor, texture and price.
Cows' Diet
One difference between Parmigiano-Reggiano and Parmesan is the way in which the cows producing the milk used in the cheese are raised. In accordance with the strict guidelines for Parmigiano-Reggiano, only the milk of cows that graze on grass and hay is used. Parmesan cheese, in contrast, is often made using pasteurized milk from cows that are generally fed a diet of concentrated feed, not grass-fed cows. This contributes greatly to the difference in taste between the two cheeses.
Ingredients
Only raw milk, natural whey cultures, calf rennet and salt are allowed in Parmigiano-Reggiano and cheesemakers use the whey from the previous day's cheese making. Parmesan makers often purchase starters from enzyme manufacturers and different brands of Parmesan often use different starters. Since different starters create different flavors, there's a lack of consistency from brand to brand. Also, Parmesan generally has a higher salt content, and allows the inclusion of additional ingredients, such as cellulose powder and potassium sorbate.
Aging
Parmigiano-Reggiano must be aged for a minimum of 12 months before a master taster checks each individual cheese; then it's often aged for another year, at least, and can be aged for as long as seven years. Parmesan is also aged, but often for a shorter amount of time. Aging the cheese gives it a stronger, more complex flavor and a crumblier texture.
Price
American-made Parmesan cheese costs significantly less than Italian Parmigiano-Reggiano, predominantly because it costs less to make. Raising high-quality, grass-fed livestock and aging each wheel for years raises the production cost of Parmigiano-Reggiano. Also, since Parmigiano-Reggiano must come from a particular area in Italy, U.S. consumers have to import it, making it more expensive than domestic Parmesan.
Rind
Each wheel of Parmigiano-Reggiano cheese is branded with the number of its cheese house, the date of production and the name of the cheese. If you want to be sure you're purchasing Parmigiano-Reggiano, just check the rind.
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