Parmesan cheese, a hard cheese with a nutty flavor, is made from skimmed or partially skimmed milk. It's aged, depending on the quality, from 10 months to 24 months. Hard cheese and semi-hard cheeses maintain their flavor and texture well when frozen. Parmesan, Romano and Asiago are examples of hard cheeses, while semi-hard cheeses include mozzarella and cheddar. Incorrectly frozen cheese or cheese frozen for too long loses its flavor and becomes crumbly. While such cheese still can be added to soups and sauces, it doesn't do well when sprinkled on salads or entrees.
Choose freezer bags that hold the average amount of grated Parmesan you normally use when preparing meals. Place finely grated Parmesan cheese in the freezer bag and distribute it evenly in the bag. Leave enough room in the bag for the cheese to expand minimally.
Seal the bag almost closed leaving just enough room to insert a straw. Insert the straw close to the top of the bag to suck out the air until the bag is completely deflated. Pull out the straw and immediately zip the bag closed.
Mark the date on the bag and place it in the freezer for a maximum of six months. When a whole bag from the freezer is not used at one time, repeat the process of sucking out the air, sealing and re-dating the package.