What Einstein Told His Cook (38 page)
Read What Einstein Told His Cook Online
Authors: Robert L. Wolke
SO, IS FOOD IRRADIATION
safe? Can anything be proven to be absolutely safe? Just read the finely printed “possible side effects” notice in every package of health-giving and lifesaving prescription drugs. We would have no marketable drugs if “absolute safety” were the criterion for approving new medicines. As pointed out by James B. Kaper, Professor of Microbiology and Immunology at the University of Maryland School of Medicine, who has seen the devastating effects of E. coli poisoning in children, “Perhaps some minor adverse effects might eventually be linked to ingestion of irradiated food. But by that time, many people, mostly children, will have died from E. coli when they would have been protected by ingesting irradiated food.”
Life is a continual risk-benefit analysis; some degree of risk is the inevitable dark shadow of any technological advance. Until the last decade of the nineteenth century, for example, we had no electricity in our houses. In the last decade of the twentieth, an average of more than two hundred people were electrocuted in the United States each year from household electrical devices such as lamps, switches, TVs, radios, washers, dryers, and so on, with another three hundred killed in some forty thousand electrical fires. We deplore and yet accept these consequences of having electricity in our homes because the benefits so vastly outweigh the risks.
We must compare the benefits of preserving foods and destroying harmful bacteria, insects and parasites—of stretching the world’s food supply and saving lives—against the vastly less likely, and certainly not life-threatening, risks.
TALKING IN A WINTER WONDERLAND
I’m confused by all the separate compartments in my refrigerator. What am I supposed to keep in each? What, for example, does the “crisper” do?
E
very time I open the refrigerator door, Alex, my Siamese cat, eyes the contents like Willie Sutton peeking into Fort Knox. He knows that that big, white impregnable strongbox contains all the pleasures life has to offer. (He’s neutered.)
We humans aren’t much different. Our refrigerators are our treasure houses. Their contents reflect our individual lifestyles even more than the clothes we wear or the cars we drive.
The main purpose of a refrigerator, of course, is to exhibit every silly object that can conceivably be glued to a magnet, not to mention the scribbled “art” of children or grandchildren. But in addition, refrigerators produce low temperatures, and low temperatures slow down every process that spoils food, from chemical enzyme reactions to the ravages of living spoilers such as bacteria, yeasts and molds.
There are two kinds of bacteria that we want to inhibit: pathogenic (illness-causing) bacteria and spoilage bacteria. Spoilage bacteria make food repulsive and inedible, but they generally won’t make us sick. Pathogenic bacteria, on the other hand, may be completely undetectable by taste or appearance, but are still dangerous. Low temperatures inhibit them both.
AND NOW, ALICE,
would you like to take a tour of Refrigerator Wonderland? Just drink this bottle labeled “Drink Me” to make you small, and follow the white rabbit into the fridge.
Alice
: Brrr. It’s freezing in here!
White Rabbit
: Exactly. We’ve landed in the freezing compartment, which is often at the top because any cold air leakage will fall down and help cool the lower parts.
A
: Just how cold is it in here?
WR
: A freezing compartment should always be at 0°F or colder. That’s 32 degrees below water’s freezing temperature.
A
: How can I tell if my freezer at home is cold enough?
WR
: Buy a refrigerator-freezer thermometer, which is specially designed to be accurate at low temperatures. Nestle it among the frozen food packages in your freezer, close the door, and wait six to eight hours. If the thermometer doesn’t read within a couple of degrees of zero, adjust the freezer’s temperature control knob and check again six to eight hours later.
Now let’s climb down into the main part of the fridge, where it’s quite a bit warmer.
A
: You call this warm?
WR
: Everything’s relative. Outside in the kitchen it’s at least 30 degrees warmer. The refrigerator mechanism is removing heat from the box we’re in, but heat is energy, and you can’t just destroy energy; remove it from one place and it has to go someplace else. So the refrigerator throws it out into the kitchen. The Mad Hatter claims that a refrigerator is really a kitchen heater, and he’s right. In fact, a refrigerator puts out more heat than it removes from its interior, because the removal mechanism creates heat. That’s why you can’t cool off the kitchen by leaving the refrigerator door open; you’d just be moving heat around from one place to another and even adding some, but not getting rid of any.
A
: How does the refrigerator remove heat?
WR
: It contains an easily vaporizable liquid called Freon, or at least it did before scientists discovered that Freon destroys Earth’s ozone layer; new refrigerators contain a friendlier chemical with the jabberwocky name of HFC134a. Anyway, when a liquid vaporizes (boils), it absorbs heat from its surroundings, which consequently get colder. (No room in here to explain why). When the vapor is compressed back into a liquid, it releases that heat back out again. A refrigerator lets the liquid vaporize here inside the box, cooling those metal coils you see on the wall. Then it compresses the vapor to a liquid again (that humming you hear is the compressor motor), and dissipates the resulting heat outside the box, through a maze of coils tucked away behind or beneath it. A thermostat turns the compressor on and off as needed to maintain the proper temperature.
A
: What is considered proper for a temperature?
WR
: The main compartment of a refrigerator should always be below 40°F. Above that temperature, bacteria can multiply fast enough to be dangerous.
A
: Can I use my new thermometer to measure that?
WR
: Absolutely. Put it in a glass of water in the middle of your fridge and wait six to eight hours. If it doesn’t read 40ºF or below, adjust the refrigerator’s main control knob and check the temperature again six to eight hours later.
A
: I’m certain that any refrigerator of mine will prove to be at precisely the proper temperature, thank you. But whatever shall I keep in it?
WR
: You know, the usual stuff. Live crabs—it sedates them so they don’t throw off their claws when you steam them; tablecloths with candle wax on them—you can scrape it off after it gets hard; damp laundry in a plastic bag whenever you can’t iron it right away; old corsages…
A
: All right, smarty. Is there anything that should
not
be kept in the refrigerator?
WR
: Yes. Tomatoes lose flavor when chilled below about 50ºF because an important flavor chemical dissipates. Potatoes get unpleasantly sweet because some of their starch turns to sugar. Bread dries out and gets stale if not tightly wrapped, yet mold spores might grow inside a plastic bag. Best to freeze it. And a large amount of leftover food that is still warm can raise the fridge’s temperature to a dangerous, bacteria-friendly level. Divide it up into small, easily cooled containers and chill them in cold water before putting them in. Don’t let them cool on the counter, because they’ll be at a dangerous temperature too long.
Alice, watch out! You’re too close to the edge of the shelf!
A
: Help! I’ve fallen down into this drawer. Where am I?
WR
: You’re in the crisper.
A
: I don’t think I want to be crisp.
WR
: It’s only for fruits and vegetables, and it controls humidity, rather than temperature. Vegetables will dry out and get flabby unless the humidity is kept relatively high. The crisper is a closed box that keeps water vapor in. But fruits require a lower humidity than vegetables, so some crispers have adjustable openings that you’re supposed to readjust every time you change the contents.
A
: Yeah, sure. Now what’s that other compartment below us?
WR
: That’s the meat keeper. It’s the coldest part of the fridge, except for the freezer. It’s at the bottom of the fridge because cold air sinks. Meats and fish have to be kept as cold as possible, but fresh fish shouldn’t be kept more than a day anyway.
And speaking of meats, I’m late for a very important “meating.” Here. Drink this other bottle of “Drink Me” to make you big again and we’ll get out of here.
Don’t forget to turn out the light.
T
he world of food is limitless. The world of science is limitless. No single work can do more than etch a tiny scratch into the surface of either one or, for that matter, into the interface between them.
In this book I have selected a number of practical issues that I hope will be useful to the curious home cook, and I have discussed them in language that is as nontechnical as possible. The most I can hope for is that these apéritifs have whetted the appetites of my readers for further understanding of kitchen science. For those whose appetites have been whetted, I list here some works that delve more deeply into the science of foods.
TECHNICAL SCIENCE BOOKS (WITHOUT RECIPES)
Belitz, Hans-Dieter, and Grosch, Werner.
Food Chemistry.
Second Edition. Berlin, Heidelberg: Springer-Verlag, 1999. The detailed, advanced chemistry of foods and cooking, with a comprehensive index.
Bennion, Marion, and Scheule, Barbara.
Introductory Foods
. Eleventh Edition. Upper Saddle River, N.J.: Prentice-Hall, 2000. A college textbook for food science courses.
Fennema, Owen R., Editor.
Food Chemistry
. Third Edition. New York: Marcel Dekker, 1996. Twenty-two academic food scientists contributed chapters on their specialties to this reference book.
McGee, Harold.
On Foods and Cooking: The Science and Lore of the Kitchen
. New York: Macmillan, 1984. A comprehensive, ground-breaking classic, covering the detailed history, traditions, and chemistry of foods and cooking.
McWilliams, Margaret.
Foods, Experimental Perspectives
. Fourth Edition. Upper Saddle River, N.J.: Prentice-Hall, 2000. Compositions, structures, testing, and evaluation of foods.
Penfield, Marjorie, and Campbell, Ada Marie.
Experimental Food Science
. Third Edition. San Diego, Calif.: Academic Press, 1990. Laboratory testing and evaluation of foods.
Potter, Norman N., and Hotchkiss, Joseph H.
Food Science
. Fifth Edition. New York: Chapman & Hall, 1995. A college textbook on food science and technology.
LESS-TECHNICAL BOOKS (WITH RECIPES)
Barham, Peter.
The Science of Cooking
. Berlin: Springer-Verlag, 2000. Introductory chemistry followed by chapters on meats, breads, sauces, etc. With 41 recipes.
Corriher, Shirley O.
Cookwise: The Hows and Whys of Successful Cooking
. New York: Morrow, 1997. What various recipe ingredients do, how they do it, and how to use them to best advantage, with particular smphasis on baking. With 224 recipes.
Grosser, Arthur E.
The Cookbook Decoder, or Culinary Alchemy Explained
. New York: Beaufort Books, 1981. A whimsical but practical collection of kitchen science information by a Canadian chemistry professor. With 121 recipes.
Hillman, Howard.
Kitchen Science
. Boston: Houghton Mifflin, 1989. Questions and answers. With 5 recipes.
McGee, Harold.
The Curious Cook: More Kitchen Science and Lore
. San Francisco: North Point Press, 1990. A collection of special topics, discussed in detail. With 20 recipes.
Parsons, Russ.
How to Read a French Fry and Other Stories of Intriguing Kitchen Science.
Boston: Houghton Mifflin, 2001. Down-to-earth, practical discussions of frying, vegetables, eggs, starch, meats, fats, etc. With 120 recipes.
(Words defined separately are in italics.)
ACID—
Any chemical compound that produces hydrogen
ions
(H+) in water. (Chemists sometimes use broader definitions.) Acids are inherently of differing strengths, but they all taste sour.
ALKALI—
In everyday usage, any chemical compound that produces hydroxide
ions
(OH-) in water, such as lye (sodium hydroxide) and baking soda (sodium bicarbonate). Chemists call such compounds bases. More strictly speaking, an alkali is a particularly strong kind of base: the hydroxides of sodium, potassium, or one of the other so-called alkali metals. Acids and bases (including alkalis) neutralize each other to form
salts
.
ALKALOID—
Any of a family of bitter-tasting, physiologically potent chemical compounds found in plants. Alkaloid family members include atropine, caffeine, cocaine, codeine, nicotine, quinine, and strychnine.
AMINO ACID—
An organic compound that contains both an amino group (–NH2) and an acid group (–COOH). In these formulas, N=nitrogen, H=hydrogen, C=carbon, and O=oxygen. About twenty different amino acids constitute the natural building blocks of proteins.
ANTIOXIDANT—
A chemical compound that prevents undesirable
oxidation
reactions in foods or in the body. In foods, the most common oxidation reaction to be prevented is the production of rancidity in fats. Antioxidants commonly used in foods include butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and
sulfites.
ATOM—
The smallest unit of a chemical element. Each of the more than one hundred known chemical elements consists of atoms that are unique to that element.
BTU—
British thermal unit, a unit of energy. Four Btu’s are approximately equal to one nutritional
calorie
. Range burners, whether gas or electric, are rated in the number of Btu’s of heat they generate per hour.
CALORIE—
A unit of energy, most often used in the context of how much energy a food provides when metabolized in the human body.
CARBOHYDRATE—
One of a class of chemical compounds found in living things, including sugars, starches, and cellulose. Carbohydrates serve as sources of energy in animals and as structural components in plants.
DIPOLE—
A
molecule
whose two ends bear relative positive and negative charges with respect to each other.
DISACCHARIDE—
A sugar whose
molecules
can be broken down (hydrolyzed) into two molecules of simple sugars, or
monosaccharides
. A common disaccharide is sucrose, the main sugar in sugar cane, sugar beets, and maple sugar.
ELECTRON—
One of the very light, negatively charged elementary particles that occupy the regions of space outside the very heavy nuclei of
atoms
.
ENZYMES—
Proteins produced by living organisms that serve the function of speeding up (catalyzing) specific biochemical reactions. Because biochemical reactions are inherently very slow, most won’t occur without the proper enzyme. Being proteins, many enzymes can be destroyed by extreme conditions such as high temperatures.
FATTY ACIDS—
Organic
acids
that are bound to glycerol to form glycerides in natural fats and oils. Most natural fats are
triglycerides
, containing three molecules of fatty acids per fat
molecule
.
FREE RADICAL—
An
atom
or
molecule
that has one or more unpaired
electrons
and is therefore highly reactive, because atomic electrons are most stable when present in pairs.
GLUCOSE—
A simple sugar, or
monosaccharide
. It circulates in the bloodstream and is the major energy-producing unit of
carbohydrates
.
HEMOGLOBIN—
The red, iron-containing protein that transports oxygen through the bloodstream.
ION—
An electrically charged
atom
or group of atoms. A negatively charged ion has an excess of
electrons
, while a positively charged ion lacks one or more of its normal complement of electrons.
LIPID—
Any fatty, waxy, or oily substance in living things that will dissolve in organic solvents such as chloroform or ether. Lipids include actual fats and oils, together with other related compounds.
MICROWAVE—
A unit of electromagnetic energy whose wavelength is longer than infrared radiation and shorter than radio waves. It penetrates solids to a depth of several centimenters.
MOLECULE—
The smallest unit of a chemical compound, consisting of two or more
atoms
bound together.
MONOSACCHARIDE—
A simple sugar that cannot be broken down (hydrolyzed) into other sugars. The most common monosaccharide is
glucose
, or blood sugar.
MYOGLOBIN—
A red, iron-containing protein similar to
hemoglobin
. It is found in the muscles of animals, serving as an oxygen-storage compound.
NUCLEATION SITE—
A spot, speck, scratch, or tiny bubble in a container of liquid that serves as a location at which
molecules
of a dissolved gas can congregate to form bubbles.
OSMOSIS—
The process in which water
molecules
move through a membrane, such as a cell wall, from a more dilute solution of a dissolved substance to a more concentrated solution of the substance, thus tending to equalize the concentrations.
OXIDATION—
The reaction of a substance with oxygen, usually with the oxygen in the air. More broadly, a chemical reaction in which an
atom
,
ion
, or
molecule
loses
electrons
.
POLYMER—
A huge
molecule
consisting of many, often hundreds, of identical molecular units, all bound together.
POLYSACCHARIDE—
A sugar whose molecules can be broken down (hydrolyzed) into several
monosaccharides
. Examples are cellulose and starches.
SALT—
The product of a reaction between an
acid
and a base, or
alkali
. Sodium chloride, table salt, is by far the most common.
SULFITE—
A salt of sulfurous
acid
. Sulfites react with acids to form sulfur dioxide gas, used as a bleach and bactericide.
TRIGLYCERIDE—
A
molecule
consisting of three
fatty acid molecules
bound to a glycerol molecule. Natural fats and oils are mostly mixtures of triglycerides.