Marlene Parrish - What Einstein Told His Cook 2

Sidebar Science: Blushing bologna

NITRITES ACCOMPLISHtheir meat-curing magic by first being themselves transformed into ( reduced to) nitric oxide (NO), a process that takes place only slowly by the action of natural antioxidants (also known as reducing agents ) in the meat. The nitric oxide then bonds to myoglobin, the main pigment in red meat, to form nitric oxide myoglobin, which has an even brighter red color. Upon cooking or hot smoking, the nitric oxide myoglobin turns into nitrosylhemochromogen (sorry about all those syllables), which is the final pinkish color typical of all cured meats.

To speed up the development of color, meat processors add a reducing agent such as sodium erythorbate, a form of (an isomer of) the sodium salt of ascorbic acid, or vitamin C. You’ll see sodium erythorbate or erythorbic acid listed as an ingredient on the labels of many cured meat products such as ham, bologna, sausages, hot dogs, and bacon.

The reducing agents used in curing have a second color-enhancing effect. Myoglobin in meats can exist in variously colored forms, ranging from purple to bright red to brown. (See “How now, brown cowburger?” on chapter 7.) Reducing agents change the brown forms to red by changing the iron atoms in the myoglobin molecules from one form (the ferric oxidation state ) to another (the ferrous oxidation state ). That slight change in the iron atoms is enough to change the color of the myoglobin molecules from brown to a blushing red.

GO SOAK YOUR…STEAK

I am a cooking teacher and cookbook author, but I have a question: Why do some recipes say to marinate meat for only one or two hours? For example, I have a pork in orange juice, a chicken in rum sauce, and a lamb in beer. It is easier for me (being on the run) to marinate them overnight or all day.

As you know, marinating—from the Latin mare, meaning sea—is the soaking of meat, poultry, or fish in a liquid concoction prior to cooking it, in an effort to improve either its flavor or its tenderness. But for a number of reasons, there can be no set rules for marinating. The amount of soaking time depends on the type and acidity of the marinade and the size, shape, and texture of the meat, among other things.

Ever since a sea nymph named Thetis dipped her son Achilles into the River Styx to make him invulnerable, the concept of a curative or restorative bath has appealed to our human yearning for quick and easy remedies. Innumerable spas and mineral-bath establishments around the world profit from this yearning by soaking their customers, both literally and figuratively. The “therapeutic baths” may consist of mud, cucumber puree, or Japanese stone juice. The fact is that a good soak in a hot bath of whatever composition (within reason) just plain feels good, and the customer goes away happy.

Unfortunately, the sources of our illnesses most often lie deep within our bodies, and “curative” elixirs simply don’t soak through our skins like ink into a blotter. (Remember blotters?) But that fact hasn’t kept the manufacturers of countless salves, balms, and ointments from claiming that they provide “deep, penetrating pain relief” or something along those lines. The most they can do is irritate the skin, whereupon the local blood circulation increases in an attempt to ameliorate the irritation, and the skin area feels warm.

And while we’re in the neighborhood of dubious treatments, let me note that magnetic fields do indeed penetrate people, but so what? The health claims for wraps and pads containing sewn-in magnets are, to stick to culinary terminology, pure bologna.

The point of this rant against quackery is that the soaking of meat, if you’ll forgive my sacrilegious characterization of the human body, cannot have an effect much deeper than its surface. And the same goes for marinating beef, pork, chicken, and fish, although, granted, we don’t marinate whole pigs, skin and all, the way we do people.

Marinades cannot infuse deeply enough into the meat, even without skin, to deposit flavor throughout its volume. Marinating is therefore primarily a surface phenomenon, the marinade’s ingredients penetrating no deeper than several millimeters (less than a quarter of an inch), depending on such factors as the density and structure of the meat, its cut, age, thickness, and temperature. Fibrous or “stringy” meats such as flank steak, however, may offer capillary channels between the fibers for the marinade to travel through, especially when the meat is cut into small pieces across the grain at an acute angle. The angle magnifies the openings of the capillary paths, just as when you cut a drinking straw on the diagonal; the circular opening becomes an oval of larger area.

To test some of these ideas, I cut raw flank steak into ½-inch by ½-inch by 2-inch bars, with the grain running the long way. I cut the ends across the grain with a very sharp knife to open as many of the putative passages as possible without crushing their ends. I then soaked the pieces at room temperature for various periods of time up to an hour in a mock marinade consisting of water, vinegar, and green food coloring.

At the end of the marinating period, I removed the meat and cut very thin slices off their ends to see how deeply the green color had penetrated. In no case did it penetrate more than a couple of millimeters.

It certainly seems that the effects of marinades may be, like a spa’s “curative” waters, merely skin-deep, although longer marinating times might achieve somewhat deeper penetration. My one experiment does not a theory make. As I have written more than once at the ends of my published research papers, “further research is necessary to establish whether these results are generally applicable to other systems.” (Translation: “I need more funding.”)

That having been said and done, marinating meats has a long history and will undoubtedly persist as long as people perceive value in it. It does indisputably flavor the meat’s surface and affect its subsequent cooking. So I’ll continue to discuss marinating with the caveat that one mustn’t expect too much of it.

A flavoring marinade, as distinguished from a marinade intended to tenderize, may consist of a wide range of seasonings incorporated into a liquid or a mixture of liquids. Wine-based marinades are quite commonly used, often seasoned with herbs, spices, or other flavorings that one expects will remain on or in the meat and contribute to its flavor during cooking. The larger the surface area of a piece of meat, the more opportunity a marinade has to affect its flavor. Thus, marinating is more effective for meat that has been cut into thin slices or into small cubes, such as for kabobs, than for thick steaks. Beyond a certain optimal point, marinating for a longer period of time will not effect deeper penetration; it can only intensify the flavor on the outer portions of the meat.

Contrary to common belief, stabbing the meat with a fork to produce punctures as entryways for the marinade is not only futile but counterproductive. Puncture wounds close up almost immediately because of the elasticity of the meat. Moreover, their latent tracks may later open up as the cooking heat shrinks the meat, thus creating exit paths for juices. Slashing or scoring a thick piece of meat before marinating, however, can boost its flavor by exposing more surface area to the marinade.

Marinades meant to tenderize tough cuts of meat almost invariably contain an acid, because acids deconstruct ( denature ) the proteins in muscle tissue. But that’s a slow process. Smaller cuts and shapes of fibrous meats will require less soaking time, but acidic marinades in general require longer times to tenderize meat than simply to flavor it.