It was back in the '80s that gastronome Nicholas Kurti, a professor of physics at Oxford University, picked up a slice of lamb and a bottle of white wine and decided to test a commonly held belief. Can a marinade really penetrate and tenderize meat? After coloring the white wine blue so he could watch its progress, he poured it around a slice of lamb. After 36 hours, it had penetrated only 10 millimeters (.39 inch).
News of Kurti's discovery has been even slower to penetrate. Most of us still believe in the tenderizing effects of marinades (most commonly, combinations of acids, oils and flavorings). But this foodie and atomic scientist proved that although acids--vinegar, lemon juice and wine, for example--as well as certain fruit enzymes in papaya, pineapple, kiwi and fig sap do tenderize meat, the process is just too slow for normal use and the resulting change in texture is unpleasant. (When Kurti tried to speed things up by using a hypodermic needle filled with pineapple juice to inject a roast, the meat acquired a mushy texture.)
There is another reason why there is little point in trying to tenderize meat by marinating it. According to Harold McGee, author of "On Food and Cooking" (Collier Books: $21), protein-digesting enzymes do most of their work during cooking and only begin to really get going at around 120 degrees. Even then, they do most of their work at the surface. "Unless you have days and days," summarized McGee, "the only thing you are going to get from marinating meat is flavor."
But what flavor! "It is right at the surface, where the meat meets the fire during grilling, that you get much of the flavor," said McGee, who is particularly enamored of the effect of red wine marinades on meat. In fact, he suggests doing a comparison test:
"First, grill an unmarinated steak and then grill one that has been marinated in red wine for about two hours," he said. "The wine-y steak will taste like there is much more steak, richer and more mouth-filling than one that hasn't been marinated. A wine marinade greatly increases the complexity of flavor and contributes chemicals that the meat doesn't have. Then when it meets the fire, those chemicals combine in tremendously complex ways and you end up with hundreds of aromatic compounds."
Fruit juices also make good marinades because of their natural sugars. "Browning reactions that give you flavor and color come from sugars reacting with proteins at very high temperatures," explained McGee. "If there is a little extra sugar, then the browning reactions are enhanced."
McGee advises against soaking meat for longer than two hours in an acid marinade. "Any longer than that and the meat will have a kind of mealy stuff on the surface. The structured meat tissue becomes tiny protein particles, fine for a pate but not what you want in a steak."
Of course, once you give up trying to tenderize meat with a high-acid marinade, you can use low-acid marinades, let the meat soak for longer periods of time and avoid the problem, suggests an article in the current issue of Cook's Illustrated. A bath of olive oil, a small amount of balsamic vinegar, garlic and herbs took 24 hours to penetrate to the heart of two-inch beef cubes.
Whatever type of marinade, if it contains acid, do the marinating in a glass, ceramic or stainless-steel dish. And remember to brush the food with the marinade during cooking.
The marinating times given in the following recipes varied from two hours to two days. You may want to experiment with them.
Stephan Pyles, author of "The New Texas Cuisine" (Doubleday: $30), likes to use this marinade for poultry, particularly chicken or quail.
THREE CITRUS MARINADE 1/2 cup fresh lime juice 1/2 cup fresh lemon juice 1/2 cup fresh orange juice 1/2 cup olive oil 4 cloves garlic, minced 2 teaspoons coarsely ground black pepper 5 bay leaves, crushed 5 tablespoons chopped cilantro
Combine lime juice, lemon juice, orange juice, olive oil, garlic, black pepper, bay leaves and cilantro in mixing bowl.
Let stand 30 minutes to allow flavors to develop before using. Makes 2 1/3 cups.
The Bali Hyatt is the source of this recipe, which appears in "Asian Grills" by Alexandra Greeley (Doubleday: $25). Use it to marinate shrimp or prawns that have been sprinkled with lime juice, salt and oil.
BALINESE CHILE MARINADE 6 shallots, peeled 6 cloves garlic, peeled 3 candlenuts or macadamia nuts 3 to 5 red chiles, seeds removed 1 medium tomato, chopped 4 tablespoons grated ginger 2 teaspoons ground turmeric 1 tablespoon oil
Combine shallots, garlic, nuts, chiles, tomato, ginger and turmeric in container of food processor or blender. Process to make coarse paste.
Heat oil in heavy skillet, add marinade paste. Saute 5 minutes. Remove paste and let cool. Makes enough to marinate 20 jumbo prawns.
This Red Wine Marinade comes from "James Beard's Theory & Practice of Good Cooking" (Knopf).
RED WINE MARINADE 2/3 cup dry red wine 1/2 cup olive oil 2 tablespoons lemon juice 3 garlic cloves, finely chopped 1 teaspoon salt 1 teaspoon freshly ground black pepper 1 tablespoon chopped dill
Combine wine, olive oil, lemon juice, garlic, salt, pepper and dill. Use as marinade for beef. Marinate 4 to 8 hours. Makes 1 1/4 cups.