Expiration Date on Milk

  • What does the expiration date on milk cartons mean?

    I have different experiences with the date:

    • There is still about a week before the expiration date but the milk has gone bad
    • It is 1-2 days after the expiration date but the milk doesn't smell or taste bad

    In both case, the milk was kept in the fridge.

    Also, even if the milk's sour (as opposed to rancid), you can still use it in baked goods. (some even call for sour milk; use it as a replacement for buttermilk, or adjust your leavening to replace baking powder with baking soda to compensate for increased acid)

  • There is a lot of variability in how fast milk will go bad.

    • How long the milk has been opened
    • Pasteurized vs ultra-pasteurized
    • Temperature the milk is kept at
    • Thermal cycling: how long and how often is it kept above 40º
    • Where in the fridge it is kept. The door will have more thermal cycling than a shelf, higher shelves tend to be warmer than lower ones.

    All of these influence how long milk stays good. The big date on the top is used by grocers to determine when it can't be sold. If you look closer there will be text to the effect of, "Use within 7 days after opening". This isn't a guarantee. Leaving the carton out while you cook will allow it to go bad faster, as will keeping it in the door. Also if your fridge is too warm for some reason, things will spoil faster.

    I'm of the opinion that how long it's been opened has more impact than the date itself.

    The type of container also seems to have an impact. I've noticed that, on average, the cartons with a "spout" don't seem to last as long as the ones with screw-tops.

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Content dated before 6/26/2020 9:53 AM