Marlene Parrish - What Einstein Told His Cook 2

One thing is inevitable, however: all foods will eventually spoil, rot, decompose, disintegrate, crumble, putrefy, turn rancid, or become just plain yucky. It’s Nature’s law, for dust they art and unto dust shalt they return. Proteins will turn soft, squishy, putrid, and green; carbohydrates will ferment and sour; fats will turn rancid. Ketchup and mustard keep so long because they contain microbe-inhibiting acid (vinegar), no fat, and no active enzymes.

In battling food spoilage, we humans have cooked our foods, smoked them, dried them, acidified them, and salted or sugared them—and, thanks largely to an American inventor named Clarence Birdseye (yes, that was really his name), in recent decades we have frozen them.

During a stint as a fur trader in Labrador, Birdseye watched the native people freeze fish and meats for later consumption. He noted that when frozen quickly in the winter instead of more slowly during the milder times, the food retained better texture, flavor, and color when thawed.

In 1925, Birdseye unveiled his “Quick Freeze Machine,” and the frozen-food industry was off and running. Today, Birds Eye Foods bills itself as the nation’s largest processor of frozen vegetables. And no, there never was a Mr. Jolly Greengiant.

Freezing preserves foods because the frozen water, a.k.a. ice, is unavailable for use by spoilage microorganisms, so they can’t grow. Refrigeration, as distinguished from freezing, will slow their growth, but there are limits. At a typical home-refrigerator temperature, ten thousand bacteria can become ten billion in a few days.

Enter preservatives: chemicals added to prepared foods to extend their shelf lives—and the lives of us who eat them. Yes, preservatives are chemicals. And yes, they are also additives, because, obviously, they have been added. (So have salt, sugar, spices, vitamins, and so on.) Quite simply, without preservatives most of our foods would spoil. And yet we are continually wooed by food labels demurely hinting at their superiority with the phrase “Contains no additives or preservatives.” Someday I’d like to see a label that adds “Will spoil almost as soon as you get it home.”

What are these chemicals? They fall mostly into four categories.

Antimicrobialsinhibit the growth of bacteria, molds, and yeasts. They include the sulfur dioxide and sulfites used in fruits, fruit juices, vinegars, and wines; sorbic acid used in cheeses; calcium propionate and other propionates used to inhibit molds in bread and other baked goods; and sodium and other benzoates used to prevent fungal growth in beverages, fruit preserves, cheeses, pickles, and many other products. Benzoates occur naturally in cranberries, while propionates can be found in strawberries, apples, and cheeses.

Antioxidantsinhibit oxidation by air, which makes fats, especially unsaturated fats, turn rancid. They include sulfites (again), BHA ( butylated hydroxyanisole ), BHT ( butylated hydroxytoluene ), TBHQ ( tertiary butylated hydroquinone ), ascorbic acid (vitamin C), and propyl gallate. They’re used in potato chips, nuts, cereals, and crackers.

Enzyme inhibitorsslow spoilage by enzyme-driven reactions in foods. Sulfites (again) inhibit enzymatic degradation reactions in fruits such as raisins and dried apricots. Acids, such as ascorbic acid and the citric acid in lemon juice, deactivate enzymes, including the enzyme phenolase, which makes apples and potatoes start turning brown as soon as they are cut.

Sequestrants,also known as chelating agents, gobble up atoms of trace metals such as iron and copper that catalyze (accelerate) oxidation reactions and cause discoloration. The most widely used chelating agent is EDTA or ethylenediamine tetraacetic acid (pronounced ETH-ill-een-DYE-a-meen-…oh, never mind). Other sequestrants are polyphosphates and citric acid.

Okay, so some of these chemical names are hard to pronounce. But contrary to the opinions of some, that doesn’t make them evil. They’re all added in tiny amounts regulated by the FDA, and nobody eats them by the spoonful.

Your alternative to eating foods containing preservatives is to visit the farm or farmers’ market every day for fresh meat and produce. Also, make your own cream, preserves, pickles, cheese, wine, potato chips, cereals, and olive oil, being sure to consume them before they go bad.

And welcome to the eighteenth century.

NO NUKES

When we travel abroad and return to the United States, we’re not allowed to bring home plants or foods for public health reasons. But aren’t these items sterilized when they pass through the airport security X-ray machines?

No. Airport security X-rays are not nearly intense enough to kill insects, parasites, and the like. The radiations used to sterilize and preserve foods are millions of times as intense.

BASICALLY, IT’S BASIC

I wonder why aluminum cookware and utensils become discolored and seemingly corroded in my dishwasher. An aluminum mesh strainer went particularly fast. Is this because there is an acid condition in the soap or water?

No, it’s not an acid. It’s the chemical opposite of an acid: an alkali, known to chemists more accurately as a base.

Most dishwash er detergents for machines, as opposed to the dishwash ing detergents for hand-washing dishes, contain the highly alkaline compound sodium carbonate, also known as good old-fashioned washing soda— not baking soda, which is sodium bi carbonate.

Alkaline chemicals are needed in the dishwasher because they gobble up grease, transforming it into soap. A soap is one of a class of chemical compounds formed by the action of an alkali on a fat. A detergent, on the other hand, is a more modern synthetic compound specifically designed to do soap’s cleaning chores. That difference doesn’t stop many people from calling all of today’s household detergents “soaps” anyway.

But I digress.

We tend to think that if a chemical is attacking and dissolving a metal, it must be an acid. And that’s generally true; a strong enough acid could devour a Humvee and spit out the tires. But aluminum is an unusual metal in that it is attacked by both acids and alkalis. (It is amphoteric .) So the alkaline sodium carbonate in the dishwasher detergent does indeed attack aluminum, at the very least eating deeply enough into the surface to make it dull and pewter-gray with aluminum compounds. For this reason most manufacturers of quality aluminum cookware advise against putting it in the dishwasher.

Worse yet, some dishwasher detergents contain potassium hydroxide or sodium hydroxide (lye), which are much stronger alkalis than sodium carbonate and will literally eat into your aluminum utensils. That’s probably what converted your mesh strainer into a basketball hoop. If you still want to wash your aluminum cookware in the dishwasher, scan the labels of the dishwasher detergents in your supermarket and choose one that contains neither potassium or sodium hydroxide nor sodium carbonate. They do exist.

There’s a second aluminum-damaging phenomenon going on in your dishwasher if the aluminum utensil happens to be touching another metal, which will most likely be stainless steel. Whenever any two different metals, in this case aluminum and what is essentially iron, are in contact while immersed in an electrically conducting liquid, an electrical (more properly, an electrolytic ) reaction takes place that attacks one of the two metals, in this case the aluminum, corroding its surface and dulling it. So if you insist on washing an aluminum utensil in the dishwasher, make sure it isn’t touching any other kind of metal.