This article is trying to explain some of the science behind marination, but I don't really understand what they are trying to say here.

As far back as pre-Columbian Mexico, cooks found that wrapping meats in papaya leaves before cooking made for more tender results. The active enzyme in the papaya leaves is papain, now refined from papayas and commercially available. The connective tissue that comes in direct contact with the protein-digesting enzymes gets broken down. These tenderizing enzymes also reduce the capability of the meat to hold its juices, resulting in greater fluid loss and thus drier meat. Enzymes are heat activated at levels between 140 F and 175 F and deactivated at the boiling point, so it serves no purpose other than flavoring to let the meat sit in a marinade at room temperature. Refrigeration is recommended to avoid the growth of harmful bacteria. Let meat come to room temperature before cooking.

So do these enzymes have a positive or negative effect? What's with that last part where they are activated at higher temperatures, but then says to refrigerate it?

  • it says right there in your quote: "Refrigeration is recommended to avoid the growth of harmful bacteria". Enzymes are not bacteria, nor harmful.
    – Luciano
    Nov 15, 2021 at 14:50
  • @Luciano yes, but what about the sentence where it says that it tenderizes the meat then in the next sentence that it dries it... "These tenderizing enzymes also reduce the capability of the meat to hold its juices, resulting in greater fluid loss and thus drier meat." Nov 15, 2021 at 15:08
  • I have never found a marinade that does anything more than just cooking a meat in sauce would have accomplish anyway.
    – Neil Meyer
    Nov 17, 2021 at 20:52

1 Answer 1


It looks like you're confusing what's going on with enzymes, bacterias and temperatures. First:

Enzymes are large molecules, mostly proteins, that speed up chemical reactions. Tenderizing meat is one of these reactions: the enzymes will break down the connective tissues in meat making it easier to be cut (or chewed).

Bacteria are one-celled organisms that require food, oxygen, water, and appropriate temperatures in order to survive.

So if you use your tenderizer enzymes at a room temperature it's warm enough to promote harmful bacterial growth too fast, your meat will spoil and it increases the chances of you getting sick when eating it. Thus, refrigerate the meat until you decide to cook it so it won't spoil.

On the other hand, the enzymes won't do anything while the meat is in the fridge (temperature too low), but you can safely cook it when necessary without worrying about harmful bacterial growth.

Lastly, when your meat reaches between 140F (60ºC) to 175F (79ºC) the enzymes stop tenderizing the meat further and the meat will just release juices and get drier, so you probably shouldn't cook it for too long (you don't need it - the tenderization process should replace long cooking times).

  • But it says they are "heat activated". Doesn't that mean that the whole tenderizing process only starts at those temperatures and at lower temperatures it does nothing? Nov 15, 2021 at 16:38
  • Also this part is contradicting "so it serves no purpose other than flavoring to let the meat sit in a marinade at room temperature." It seems to insinuate that the enzymes only do their work in that small interval of temperatures before reaching boiling point when it stops. It doesn't make sense. Nov 15, 2021 at 19:42
  • @MichaelMunta at lower temperatures the chemical reactions slow down significantly to the point that it might not be noticeable. Re your 2nd comment: no contradiction; where I live 140F is way above room temperature.
    – Luciano
    Nov 16, 2021 at 10:15
  • But that means then that I can keep the meat with enzymes for longer periods of time without them doing anything in the fridge (no bacteria/no mush?). So the whole marination process is for flavoring, but when we actually start cooking is when the enzymes do their work? Nov 16, 2021 at 10:56
  • The marination is also to allow the enzymes to further penetrate the meat (to some extent). Once the meat reaches that temperature range the enzymes will actually break down whatever connective tissues they are in contact with.
    – Luciano
    Nov 16, 2021 at 13:29

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