Last night, I made Tacos al Pastor from a recipe I found on Epicurious. I have made them before but this recipe was definately the best. The dish calls for pineapple in the marinade. However, some of the reviews indicated that an enzyme unique to pineapple would make the meat mushy. I have cooked with pineapple before and have not had any problems. So, I threw caution to the wind and they tacos turned out great.
Does anyone know about the enzyme that is noted in the comments? What chemical reaction if any does it have on meat?
BTW, if you try this recipe, definately make the cilantro-onion relish and reserve some of the marinade in lieu of the Two-Chili Salsa.
The enzyme is papain (also found in papaya, hence the name) and it is a relatively non-specific protease. Keeping the pineapple-meat mixture refrigerated during marination keeps the enzyme activity low, which perhaps accounts for your lack of "mushy meat." Note that the recipe calls for separate grilling of the pineapple from the meat. This achieves two goals: the pineapple and meat cook for different amounts of time, and the pineapple is not in contact with the meat when it is heated, so the papain doesn't have a chance to work on the meat before it is heat-inactivated by the grilling process.
Papain is inactivated in canned pineapple; this is the main reason most recipes that call for grilling pineapple slices with ham call for canned rather than fresh pineapple.
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Diana R. Tomchick
University of Texas Southwestern Medical Center
Department of Biochemistry
5323 Harry Hines Blvd.
Dallas, TX 75390-8816, U.S.A.
Pineapples contain bromelian, a protease. Hence gelatin cannot be used with fresh pinepples.
Papain, also a protease is predominant in raw, green papaya, which is why papaya is added to some marinades for meat tenderizing.
Both papain and bromelain extracts are used in commercial meat tenderizers and in some digestive supplements
Likewise figs contain ficin and kiwi contains actinidin that are also proteolytic enzymes
See, for example
Subha R. Das
Carnegie Mellon University
Creator of The Kitchen Chemistry Sessions
In my forays as an amateur chef, I've also run across some recipes, mostly from India, that call for a marinade of yogurt with the juice that comes along with canned pineapple (and some other spices, cardamom, etc.). These are usually lamb dishes, and lamb can be a particularly tough cut of meat depending on the quality. The lamb is usually marinated in the yogurt/pineapple mixture, but then the meat pieces are removed before cooking. Makes sense, based on the previous posts!
canned pineapple juices or fruit chunks have been retorted (severe heating). Enzymes are no longer active
yogurt may have some proteases secreted by the cultures in it.
Although nobody marinates their meat with cheese, cheeses contain proteases also, such as chymosin, trypsin and pepsin. These are also produced in the stomach and pancreas of the animal providing the milk. Blue cheese and camembert contains these protein breaking enzymesm, plus lipases (fat breaking enzymes).