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?
