Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Milk Souring Mystery!

  1. Sep 4, 2007 #1
    For the past year I haven't been able to keep milk in my fridge for more than 4-5 days. I always buy the freshest milk, not expiring for a couple weeks from purchase. However, the milk sours in my fridge in 4-5 days no matter what brand or size of milk. After 4-5 days the top of the milk is filmy and smelly. Even more drastic I bought two 12oz bottles of milk yesterday. I drank one last night and it was fine, but I went to drink the second this morning and it was rank, I poured it down the drain and it was chunky. My fridge cold level is 7 out of 10. 10 being coldest. I have no problem keeping any other foods for a long time and everything feels cold to the touch. Anyone have ideas why I can't keep milk for long, it's sooooo annoying!
     
  2. jcsd
  3. Sep 4, 2007 #2

    Math Is Hard

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    We should buy you a cow.
     
  4. Sep 4, 2007 #3

    turbo

    User Avatar
    Gold Member

    Radio shack sells a really inexpensive digital thermometer and humidity gauge that records highs and lows. That would tell you if your refrigerator is getting cold and if it is staying cold.
     
  5. Sep 4, 2007 #4

    G01

    User Avatar
    Homework Helper
    Gold Member

    I agree. You might want to look into the temperature of the fridge. It may not be cold enough for the milk in there.
     
  6. Sep 4, 2007 #5

    berkeman

    User Avatar

    Staff: Mentor

    Random thought -- is your milk sitting right next to the electric light bulb in your fridge? Maybe the switch on the door is defective, and the bulb is staying on, heating just that one part of the fridge. Maybe try unscrewing the bulb for the next couple of weeks, to see if that fixes the problem. And if it does, get a new switch.
     
  7. Sep 4, 2007 #6

    Lisa!

    User Avatar
    Gold Member

  8. Sep 4, 2007 #7

    Moonbear

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    A few potential sources of problems:
    1) Do you always buy milk from the same store? Perhaps the store employees are not very vigilant about getting it off the hot loading dock and into the coolers, shortening the shelf life considerably.

    2) When you buy the milk, do you pick it up first or last during a shopping trip? Could you be letting it warm up enough in the shopping cart to let the bacteria start growing?

    3) What about on the way home? Is it sitting in the hot trunk of the car for a while? I try to keep the milk cold on hot summer days by keeping all the cold/frozen goods together in the same bag(s). Pack it with the frozen peas and ice cream, and put it on the floor of the car interior rather than the trunk so it gets the air conditioning you're getting.

    4) Have you thoroughly disinfected your fridge since discovering this persistent problem? You might have one of the bacteria that sours milk growing in a nice culture in there somewhere (have much yogurt with active cultures?) that's getting into open milk containers (doesn't explain the sealed container issue though). I'd suggest pulling everything out and cleaning the entire interior of the fridge with a bleach solution, rinse thoroughly and see if the problem goes away. Keep yogurts and cheeses in sealed bags or containers to prevent cross-contamination.

    5) As suggested above, toss a thermometer into the fridge and check that the temperature setting is sufficiently cold for the milk. Also, check the door seal, especially if it's an older fridge. If there's a leak near where you keep the milk (probably the top shelf or door), that part of the fridge may not get cold enough, while stuff down in crisper drawers is freezing (that happened to me once with a leaky door seal...fridge kept running and cooling the bottom, but the top shelf was still a bit on the warm side due to the leaky door seal).
     
  9. Sep 4, 2007 #8
    Really great ideas and things to consider, thanks all, I will return with a followup in a week or so! I need my calcium! :)
     
  10. Sep 4, 2007 #9

    DaveC426913

    User Avatar
    Gold Member

    One other factor: if you are buying it from the same place, the temp at which they keep their fridges will factor strongly into how long the milk lasts.

    Long ago I read some guideline that compared store storage temperature to longevity. It was like: for every degree above X, milk will spoil Y days sooner. The temp. ranged from optimal (a few degrees above freezing) to just below room temp., while the longevity ranged inversely from a week or more down to less than a day. (I say all this in long form because I don't want to provide misinformation in the form of an equation).
     
  11. Sep 4, 2007 #10

    Astronuc

    User Avatar

    Staff: Mentor

    Also check the expiration date on the milk carton, and storage conditions where one buys the milk.

    I used to work in a grocery store, and when I stocked the dairy section, I was told to put the older stuff in the front and hold back on the fresh so the store could get rid of the stuff about to expire. I didn't like doing that, and if someone asked, I gave them the fresh dairy product.

    It's best to get one's milk from the back of the dairy case where it is colder, and probably fresher.

    Certainly one needs to verify the operation of one's refrigerator at home. One can get an inexpensive digital thermometer, or even conventional liquid one, at a local pharmacy/apothecary/drug store.
     
  12. Sep 4, 2007 #11

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    I reckon your fridge has been contaminated by milk drinking nasty bugs.
     
  13. Sep 4, 2007 #12

    Evo

    User Avatar

    Staff: Mentor

    I think Dave may have hit the problem, if not, I'll go with Brewnog. This is something I could see happening in Wolram's fridge.
     
  14. Sep 4, 2007 #13

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Maybe you need to move closer to some cows! Oh, wait a minute...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Milk Souring Mystery!
Loading...