Do marinades really work? The answer is both yes and no. Research conducted in laboratories, where the acidity and duration of a marinade are tightly controlled, has led to positive results, but not always. Some tough cuts of meat did become tender, but not miraculously so.
So what is marinade, anyway? Essentially, it’s a mostly liquid mixture consisting of various herbs and spices, and often contains an acidic element.
The acidic ingredient is a marinade’s tenderizing element. Some, such as lactic acid (found in yogurt and buttermilk), seem more effective than others. However, there is often a minimal tenderizing effect. Why? This is because marinades barely penetrate the surface of pieces of meat, while collagen (the elastic element in meat that the tenderizer is trying to soften) is present throughout.
Marinating longer in a highly acidic marinade is certainly more effective, but a high dose of acid may also cause its share of problems. Meat can get an unpleasant sour taste and change in appearance. Robust meats, such as beef and lamb, can tolerate such treatment, but more delicate choices, such as fish, seafood and poultry, may suffer. Indeed, highly acidic ingredients, such as lemon juice and lime juice, cause proteins to tighten on the surface of a marinated food over time Protein bonds tighten, water is squeezed out, and this makes the food even tougher and drier, the exact opposite of the desired tenderizing effect.
So, why marinate?
To add flavour! Salt and aromatic molecules found in herbs, spices and vegetables (such as garlic and onions) slowly penetrate the surface of a food, giving it another layer of flavour. But, similar to the tenderizing effect, this only takes place on the surface. The oil in a marinade is important in this regard: many aromatic molecules dissolve in oil. It therefore helps to "extract" flavour from its ingredients and transfer them to the meat or fish. It is a good idea to crush or finely chop solid ingredients, such as garlic and ginger, in order to maximize the effect.
Since marinades won’t create any tenderizing miracles, you only have to marinate long enough to add some flavour. The suggested time below takes a few factors into account, a meat’s robustness and its ability to tolerate an acidic element. If your marinade is mainly composed of oil, herbs and spices, with low acidity, you can marinate longer. Remember that marinades act on the surface: the thinner the cut, the greater the effect of the marinade. For thicker cuts, prick the piece in several places with a knife or fork to allow the marinade to penetrate more deeply.
A protease is an enzyme (enzymes are specialized proteins) capable of attacking muscle fibres and collagen in meat, and literally breaking it down bit by bit. This enzyme is found naturally in some fruit, such as pineapple, papaya and kiwi. You can also buy it in a powdered form that usually contains papain, an enzyme present in papaya. It should be noted that these enzymes do not take effect during the marinating session, but are instead heat activated at the beginning of the cooking period. The problem is they are so efficient that they can turn the meat surface mushy and unpleasant. See for yourself: the next time you make brochettes, alternate fresh pineapple cubes with beef, pork or chicken cubes. Cook on the barbecue over medium-low heat and notice how meat surfaces in direct contact with the pineapple turn soft and mushy.
The longer you marinate, the better it is? This may be true for robust meats, such as beef and lamb, but is not the case for delicate products such as fish.
Well marinated: A salmon trout fillet left for 30 minutes in a marinade composed of 60 ml (1/4 cup) of olive oil, 15 ml (1 tbsp.) of lime juice, 5 ml (1 tsp.) of honey, 1 clove of minced garlic, 1 sprig of fresh thyme, cracked pepper. The flesh remains soft and moist, and maintains its original appearance.
Too much marinating: The fillet starts to become slightly opaque after two hours in a marinade. In addition, it will lose 1% of its weight. After 12 hours in a marinade, the fillet will be firm and opaque, as if the surface was cooked. It will have lost 5% of its weight, as well. Why? Fish proteins have coagulated due to the acidic effect and, as a result, the flesh is hard and has lost some of its delicacy.
Choose good cuts
For grilled meat that really melts in your mouth, it’s better to start off with a tender cut than rely on marinade to tenderize it. Fish, seafood, poultry and many cuts of pork are naturally tender. These are excellent grilling choices. As for beef and lamb, you have to choose a good cut. Your butcher can suggest the best pieces for successful grilling. Whatever you choose, don’t overcook it! Overdone meat is dry and hard to chew.
How long should you marinate it?
Red meat (beef, lamb, game): 4 to 12 hours
Poultry and pork : 4 to 6 hours
Fish, shrimp, scallops : 30 to 60 minutes