Part 4 (2/2)
Why Must the Food for Frying Be Dry?
We have seen that there must be an abundant quant.i.ty of frying oil, because the thermal inertia of a heated body is proportional to its ma.s.s. Cold pieces of food introduced into heated oil cool the oil less if there is a large amount of it.
Let us also not forget that the pieces of food should be cut small, if possible, so the inside has time to cook before the surface molecules begin to burn.
And, finally, let us remember that foods placed in hot oil must be dry. First of all, it would be a useless loss of heat if the oil first had to evaporate the water on the surface of the food before carrying out the actual frying. Second, one can avoid spattering fat if the foods for frying are dry. When water is suddenly immersed into oil at a temperature much higher than its vaporization temperature, it is transformed very quickly into vapor and, by expanding so violently, spatters fat everywhere.
What to Fry?
I will not launch into a tiresome list, but I do want to note that the flaky, crispy consistency, the golden color, and the characteristic flavor of fried foods are due in part to the coagulation of proteins and the caramelization of glucides (sugar and starch) over the course of the frying. That is why potatoes were predestined to be deep-fried: they consist, on the surface, of sugars and starch that are favorably transformed.
Nevertheless, the preparation of fried potatoes can go wrong when too many or too large pieces are placed in the oil. The fat (which smokes at about 190C [374F]) is cooled to 130C (266F) and remains at that temperature, so the potatoes do not cook.
For perfect french fries, place the potatoes in a large quant.i.ty of hot oil. After about five minutes, turn up the heat to increase the oil temperature, so that a crisp crust forms. Then, as soon as you remove them from the oil, blot the french fries with paper toweling. This method takes into account the pressure (yes, the pressure!) inside french fries. When measured, the pressure can be observed to increase gradually as the water in the potato evaporates as they cook. Thus a french fry has a crisp outside, some puree, and a lot of vapor inside (cutting one open will reveal this). When the french fries are taken out of the oil, the pressure decreases because of the recondensation of the vapor into water, which sucks in the oil on the potato's surface. Immediately blotting the french fries reduces the amount of oil they absorb.
For foods that do not contain glucides on the surface, bread crumbs are a good solution, since they come from flour, which is essentially composed of glucides. However, since bread crumbs will not stick to meat, for example, you must coat such foods in beaten egg before applying the bread crumbs. The egg binds the bread crumbs to the meat, and it also provides proteins that react chemically with the sugars through Maillard reactions (again!).
You can improve the process and prevent the crust that forms from coming detached by first dusting the meat with flour, then dipping it in egg, and finally applying the bread crumbs. The coagulated layer of bread crumbs will stick to the meat because of the starch that is formed. This method is even more effective if you first pierce the food with a fork. The egg and flour penetrate these holes and further anchor the fried coating to the food.
Sautes and Grills Braising with Very High Heat Strictly speaking, to saute is to cook meat, fish, or vegetables in a fatty substance over high heat, uncovered, and without adding any liquid. In practice, however, for large pieces of food especially, this first phase of cooking must be followed by more gentle cooking, in an open pan, so that the odorant molecules in the vapor can add the finis.h.i.+ng touches to the initial saute. A true saute differs from braising in that, with an uncovered pan, no vapor limits the cooking temperature. As with deep-frying, cooking takes place at a temperature higher than the 100C (212F) of boiling water.
For sautes, the fatty substance is of primary importance. To obtain good sauteed meat, vegetables, or fish, clarified b.u.t.ter is essential because, in addition to its flavor, it can withstand a temperature higher than can natural b.u.t.ter without burning. Can higher temperatures also be attained by mixing oil and unclarified b.u.t.ter? Our experiments did not confirm this old wives' tale.
For grilling as well, the cooking takes place at high temperatures, although without oil. The meat rests in direct contact with the grill. To improve the contact and transfer of heat, the meat can be brushed with a little oil or clarified b.u.t.ter.
Many culinary works claim that the superficial caramelization of the meat's proteins, in forming a crust, forms an impenetrable layer that traps the nutritive juices. (We have seen that there is no caramelization involved and there is no impenetrable layer; I will come back to this in the next section.) Additionally, books advise not to salt or p.r.i.c.k the meat so as to avoid the loss of juices. Do you recall that these same instruction were given with regard to roasts?
Good Sense Gone Wrong Adding salt is certainly to be avoided in some cases, because the phenomenon of osmosis causes the juices to escape the meat when muscular fibers are cut and open, and p.r.i.c.king the meat is harmful because it creates channels from which the juices can leak out. But the impermeable crust is a myth for which the German chemist Justus von Liebig (1803-1873) is responsible.35 In the nineteenth century, Liebig understood that heat coagulates the proteins on the meat's surface. He extrapolated, however, when he a.s.sumed that the coagulated crust trapped the juices. The idea that cooking with a hot flame can cauterize meat and limit the loss of juices, though never proven, traveled rapidly to England, then to the United States, and finally back to France, where it has reigned in error until very recently. In the nineteenth century, Liebig understood that heat coagulates the proteins on the meat's surface. He extrapolated, however, when he a.s.sumed that the coagulated crust trapped the juices. The idea that cooking with a hot flame can cauterize meat and limit the loss of juices, though never proven, traveled rapidly to England, then to the United States, and finally back to France, where it has reigned in error until very recently.
Many observations carried out by Harold McGee in Palo Alto, California, demonstrate the falseness of Liebig's hypothesis.36 First of all, a grilled steak sizzles while it cooks. That is a sign that liquid-the juices-is escaping the meat and vaporizing. The sizzle is the sound of the vapor spurting out. First of all, a grilled steak sizzles while it cooks. That is a sign that liquid-the juices-is escaping the meat and vaporizing. The sizzle is the sound of the vapor spurting out.
Second, even if the steak is removed from the pan, the plate that receives it is soon filled with juices. These juices escape the meat as soon as it is finished cooking. Thus the supposedly impermeable layer is hardly that.
Third, if the pan is deglazed with wine, for example, it is to dissolve the juices that have escaped the steak during the cooking process and caramelized deliciously.
Fourth, that vapor that is released throughout the cooking: what is it, if not the juices vaporizing?
All in all, it seems obvious that juices leave meat as it cooks, even if the surface is seared at the very beginning of the cooking process. By contracting the connective tissue that surrounds the muscle fibers, the cooking process prompts the expulsion of the meat's juices.
So how to retain the most juices possible in grilled or sauteed meat? One solution consists of not overcooking it, naturally. The less the connective tissue is contracted, the less juice is expelled. A second solution consists of cooking with high heat. In this way, the meat cooks rapidly, and the juices do not have time to escape the meat in very significant amounts. Third, salting and p.r.i.c.king the meat should be avoided, for the reasons previously shown. Finally, the grilled meat should be eaten without delay, as soon as it is cooked. In this way, the juices will not have time to leak out onto the plate.
As an aside, if a sauce is served with the grilled meat, it must be thickened a bit more than may seem necessary, because it may be diluted by the juices that will inevitably leave the meat and run out onto the plate.
Even More Tender Between Tough and Putrid Very fresh meat is tender, but fresh meat is tough; gradually it becomes tender again, and then it rots. How to conserve it in that precarious state in which it does not require excessive chewing but neither does it release an unbearable odor, revealing an unhealthy degree of putrefaction? Our ancestors invented many processes for long-term conservation: smoking, salting, drying. But today's cooks can get meat anytime at all from the neighborhood butcher, who sells cuts that are aged for exactly the right amount of time. They no longer have to solve the problems of long-term conservation. Beginning with products aged under supervision, their chief goal is to obtain meat that will be tender after cooking.
Our consideration of stews showed us the importance of lengthy cooking in a liquid, in order to break down the collagen fibers that toughen meat. Other processes produce the same result. Hanging, marinating, and ”proteasizing” are appealing for reasons it would be a shame to overlook.
By the Neck or by the Beak?
Let us read Brillat-Savarin: Above all other feathered game should come the pheasant, but once again few mortal men know how to present it at its best.A pheasant eaten within a week after its death is more worthless than a partridge or pullet, because its real merit consists in its heightening flavor.37 How can we attain the summits reached by the master? Ask all around. You will hear that hanging game is an abominable operation, that our forefathers ate putrid meat, that, after being suspended by its neck, the pheasant was consumed when it fell, its head detaching from its body because of rotting. Is that the last word on the subject? Would we be here today if our ancestors willingly poisoned themselves on rotten pheasant? And who among us has seen, with his own eyes, the hanging of a pheasant by its head?
Bibliographic research has shown me that hanging pheasant does not follow any absolute rule but that good sense is essential. First of all, yesterday's great cooks did not recommend hanging pheasant by the neck, or even by the beak, but by the tail feathers. Being generally a heavy bird, a pheasant falls well before it rots.
A second precept is that the animal must be hung with its feathers still on, which protects it from insects and other small pests who would threaten our feast. Finally, the length of the hanging depends on the temperature and the weather. Just as we see fish turn when they are not cleaned and there is a storm, a pheasant can only hang for two or three days when the air is humid but can remain in a cool draft for six days when the weather allows. Supposedly, during this operation, a special juice that is present in the shaft of the feathers is reabsorbed into the flesh. This claim deserves an experimental study.
Brillat-Savarin, whose colleagues, it is said, took offense at the odor of hung meat that accompanied him (supposedly he put pheasants in his pockets to age them), wrote that ”the pheasant is an enigma whose secret meaning is known only to the initiate.”38 How to become an initiate? How to cook a pheasant with the attentive care necessary to take it to the point where it surpa.s.ses a good chicken? How to become an initiate? How to cook a pheasant with the attentive care necessary to take it to the point where it surpa.s.ses a good chicken?
According to Grimod de la Reyniere, ”the pheasant is done on a skewer, wrapped in paper, well b.u.t.tered. The paper is then removed to give it good color; then it is served in a verjuice sauce, with pepper and salt.” Today, instead of the verjuice, made from unripe grapes, a slice of lemon, salt, and pepper can be subst.i.tuted.
How Many Days for Marinades?
If hanging is good for pheasant and its feathered cousins, marinade is more suitable for large, furry beasts, like wild boar (which is often tough), mutton, and beef.
The process is simple. The meat rests in a mixture of wine, oil, vinegar, spices, various condiments, and a few vegetables (this mixture can be cooked beforehand). With time, the meat becomes tender and flavorful. Subsequent cooking completes the dish, be it grilling, roasting, cooking it in the marinade itself, in short, whatever you prefer.
What are the princ.i.p.al elements for a marinade? Vinegar, flavors, time.
Vinegar is an acid that attacks the connective tissue and breaks it down. That is one reason it was thought that the meat gets tender, but not the main reason. From our laboratory experiments, we concluded that meat becomes tender in a marinade because, while it is protected from putrefaction, the muscular fibers age and protein aggregates are slowly dissociated, just as when butchers age meat in their special refrigerators. Previously, we had thought that tenderization occurred where the flesh had been in contact with the marinade. But our more recent experiments have shown that a marinating solution penetrates meat to a much more limited extent than our model systems had suggested, in which this diffusion occurred at the rate of about ten millimeters per day.
Other experiments, more culinary in nature, lead to impressive results. A marinated roast pork can be taken for a leg of very young wild boar; marinated mutton can pa.s.s for venison.
Whether you wish to fool your guests or not, serve marinated meats with red currant jelly: it's delicious!
Pineapple Power Having explored various methods of tenderizing meat, my esteemed friend Nicholas Kurti, whom I have already mentioned, during a March 14, 1969, meeting of the Royal Inst.i.tution to which the BBC had been invited, demonstrated that an injection of fresh pineapple juice into a pork roast resulted in absolute tenderization.
Another English fad? Not entirely, because first, although Nicholas Kurti was a professor of physics at Oxford and a member of the very old and venerable Royal Society of London, he was Hungarian by origin. A longtime record holder for the lowest temperature ever reached (a millionth of a degree below absolute zero, that is, about 273 degrees below the temperature at which water freezes), Nicholas Kurti was a pa.s.sionate cook. With his public experiment, he wanted to demonstrate the power of the enzymes in pineapple juice and confirm experimentally a method extolled by the Aztecs.
Enzymes are molecules that promote various reactions in live bodies. They are found in all living cells and notably in fresh pineapple, papaya, and fig juice, among other plant products. The specific enzymes found in pineapple, papaya, and fig (bromelain, papain, and ficin, respectively) have one peculiarity: they are proteolytic, that is, they break down proteins. Now, meat, as we have seen on several occasions, is composed of many proteins; collagen, especially, responsible for meat's toughness, is a protein.
Nicholas Kurti demonstrated how to put the useful properties of these enzymes to work in preparing meat. He squeezed a fresh pineapple, placed the juice in a hypodermic syringe, and injected the pineapple juice into a pork roast (in just one-half in order to compare the results of the enzyme action). He let the roast rest for a few minutes, so that the enzymes would have time to react. Then he put the roast in the oven and let it cook for less time than necessary to cook the untreated half thoroughly.
Taking the roast out of the oven, he cut it into slices. The half that had not received the pineapple juice was still the pink color characteristic of undercooked pork, even though the meat was covered with a crisp crust. By contrast, the meat on the other side was almost reduced to puree. Naturally, the meat had a distinct pineapple taste, but isn't there a recipe for pork with pineapple?
Medicine and Cooking ”From your foods, you will make your medicine,” said Hippocrates. While we wait for modern medical nutritionists to define for us the perfect foods to ensure our health and longevity, let us borrow one of their instruments: the syringe.
This tool, used by Nicolas Kurti for his pineapple juice injection, can also improve the marinating process.39 While the meat marinates, draw off the marinade at regular intervals and use the syringe to inject it into the meat. The results are superb because the marinade works from the inside out, and the preparation time can thus be shortened. While the meat marinates, draw off the marinade at regular intervals and use the syringe to inject it into the meat. The results are superb because the marinade works from the inside out, and the preparation time can thus be shortened.
In addition, a number of cookbooks mention that marinated meat must not be roasted, for fear of drying it out. That is correct, according to my experience, but by injecting the marinade into the center of the meat, you can avoid that danger.
<script>