When cheese is made with calf rennet, is it possible that the cheese contains cells of this calf (stomach)?

Dried and cleaned stomachs of young calves are sliced into small pieces and then put into salt water or whey, together with some vinegar or wine to lower the pH of the solution. After some time (overnight or several days), the solution is filtered. The crude rennet that remains in the filtered solution can then be used to coagulate milk. Does this filtering exclude all stomach cells of the calf?

  • $\begingroup$ Somehow I doubt any whole cells exist after the process, the whole thing seems designed to break living tissues down and to denature protein. That being said calf stomach cells may be tough so +1. $\endgroup$ Commented Jan 7, 2019 at 2:01
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    $\begingroup$ @Duckisaduckisaduck - One would hope it doesn't denature protein. the whole puropse for the sacrifice is to obtain a complex set of enzymes. Denatured enzymes would be useless. $\endgroup$ Commented Jan 7, 2019 at 5:13
  • $\begingroup$ @anongoodnurse My error, I read too much into the adding vinegar part. $\endgroup$ Commented Jan 7, 2019 at 12:40
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    $\begingroup$ I’m voting to close this question because it relates to food analysis rather than a biological problem. $\endgroup$
    – David
    Commented Jan 8, 2022 at 20:02

2 Answers 2


95% of cheese does not use animal rennet.

Many cheeses use no rennet.

Of the cheese that do use rennet the vast majority use rennet derived from bacteria, fungi, or plants. often because it is cheaper, easier, and more humane.

Of cheeses that do use rennet 5-10% of it makes it into the final product, so yes if your cheese uses calf rennet the cheese likely contains calf enzymes.



Yes it is possible, filtering is unlikely to be fine enough to remove all cells (though the presence of intact cells based off of the culturing methods is unlikely), note though that modern methods of rennet extraction from stomachs are different than what you described. There are also non-calf rennet made with everything from fungi and bacteria to vegetables. Source

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    $\begingroup$ It all depends on the filter. Standard filters for preparations of this sort will be 0.45 micrometers (um), which is definitely smaller than a mammalian cell at 100-300 um, and even smaller than most bacterial cells at 0.5-10 um. $\endgroup$
    – bob1
    Commented May 12, 2021 at 23:09
  • $\begingroup$ Please post references (ideally to primary literature) that support the part of your answer that is actually relevant to the OPs question. Without that support, your answer is indistinguishable from opinion and thus not a good fit for this site. Thanks. $\endgroup$
    – tyersome
    Commented May 13, 2021 at 4:49

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