The "sell-by" date on a brick of cheddar is nonsense. It's really only
used for rotation purposes on an aged cheese. Haven't you ever seen 5
year old cheddar or provolone? This is another one of "big brother's"
ways of protecting us from ourselves. I was a cheesemaker for over 20
years. Enjoy the cheddar,and if mold appears.... scrape it off and
enjoy!
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Fresh cheeses, such as cottage cheese and ricotta cheese will last you
well beyond their "sell-by" date also. I assume your fridge is cold
enough and sanitary. Let your nose be your guide.
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Sal