Ziploc package bearing an O-U symbol

Why would a disposable plastic container, such as the one depicted above, need an O-U?

  • 1
    Why do you think it does need an OU? Please edit to clarify
    – Double AA
    May 2, 2017 at 19:16
  • @ClintEastwood You should summarize this as an answer. May 2, 2017 at 19:43
  • 2
    related judaism.stackexchange.com/q/56244/759
    – Double AA
    May 2, 2017 at 19:54
  • It's been a while since I read that Star K article, so, I don't offhand recall the exact concern. Part of the deal is probably marketing, as well. It seems that kashrut markings are popping up on products that probably don't need them. Paper plates have them, I've seen it on foam cups. I haven't seen them on linen table cloths or napkins, yet, but I wouldn't be surprised if it's out there. (Come to think of it, do they put certification on pet food?)
    – DanF
    May 3, 2017 at 14:17

1 Answer 1


A number of kashrut certification agencies (led by Star-K and the OU) discovered that plastic packaging material suppliers were using animal-based additives (e.g., tallow, animal fat) in the plastic resins (e.g., as lubricants) and that these additives could migrate into the food. Interestingly the Food & Drug Administration requires these chemicals to be food-grade because of this interaction with food.

This can potentially represent a kashrut issue when heating up food in these packaging material so the Star-K and OU worked with the chemical suppliers to these packaging companies to switch from animal to vegetable additives and started putting kosher logos on these new packagings.

For further details see here from the Star-K.

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