This paper says that after: "Lactobacillus alimentarius 15M, Lactobacillus brevis 14G, Lactobacillus sanfranciscensis 7A, and Lactobacillus hilgardii 51B were selected and used in sourdough fermentation", "The concentrations of free amino acids, especially proline and glutamic and aspartic acids,... increased in sourdoughs". According to what I have read from other sources, it seems that the above four bacteria species are indeed found in regular sourdough starters. Moreover, the paper states: "The main proteolytic activity was first attributed to endogenous flour enzymes, such as aminopeptidase, carboxypeptidase, and endopeptidase ...; later, enzymes of fortuitous microorganisms and lactic acid bacteria were also presumed to have a role.... Proteolysis in sourdoughs has been found to be higher than in yeasted and unstarted doughs.... "

This all seems to indicate sourdough has a very high proteolytic activity. Would it be enough to have a noticeable impact on the tenderness of meat if it was marinated in sourdough starter at room temperature for say, an hour, or in the fridge, say for 12 hours?

Lastly, how would it compare to the tenderization by say, bromelain from pineapple juice, or papain from unripe papaya fruit?

  • I don’t know about sourdough, but there are discussions online about doing it with koji (mold used to make sake & miso): cooksillustrated.com/science/786-articles/feature/koji ; popsci.com/cook-steak-koji-fungus
    – Joe
    May 6, 2022 at 15:05
  • 1
    @Joe interesting stuff. I find the fact that koji was able to preserve meat for five straight days (which I'm presuming is at room temperature?) far more astonishing than the fact that it tenderized the meat. However, I'd be highly cautious keeping meat out at room temperature for anything more than two hours unless it's specially prepared for preservation. The fact that this would entirely be an experiment with sourdough starter which we don't know enough about to ascertain if it would be enough to deter harmful bacteria certainly makes it dangerous. May 7, 2022 at 9:17
  • The first link I gave used warm fermenting. The second link was steak at fridge temps for 2 days, so should be safe by modern US standards/regulations. The first one also mentions salting meat first to cure it slightly to kill bacteria, then coating in koji
    – Joe
    May 7, 2022 at 10:14
  • Congratuations on managing to come up with a sourdough question that's never been asked before.
    – FuzzyChef
    May 7, 2022 at 18:51

1 Answer 1


I haven't looked into any scientific papers, but interestingly there are a few recipes online for "sourdough" steak. Of course using yogurt as a tenderizing (as well as flavoring) marinade base is used in several cultures, so it makes complete sense that sourdough starter will have a similar impact. This sounds like a fun experiment to try...marinating in sourdough starter for varying times and doing a triangle test with controls would be the way to go, I think.

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