What Einstein Told His Cook (8 page)

But are sea salts perhaps still distinguishable from one another in flavor, even though dissolved in water? In a series of controlled taste tests reportedly conducted in 2001 under the auspices of the Leatherhead Food Research Association in England, panels of tasters attempted to distinguish among a number of different salts dissolved in water. The results, as reported in
Vogue
magazine, were wholly inconclusive.

One common assertion is that sea salt is saltier than shaker salt. But since they’re both about 99 percent pure sodium chloride, that can’t be true. The idea undoubtedly arose from the fact that in on-the-tongue taste tests, the flaky, irregularly shaped crystals of many sea salts dissolve instantly, giving a quicker rush of saltiness than do the small, compact, slow-dissolving little cubes of shaker salt. But again, it’s not the ocean that made that difference; it’s the shapes of the crystals.

The notion that sea salt is saltier has led to the claim that one can use less of it in seasoning. (“Good for those watching their sodium intake,” trumpets one sea salt manufacturer.) Obviously, because sea salts generally have big, complexly shaped crystals that don’t pack down as tightly, a teaspoonful will contain less actual sodium chloride than a teaspoonful of tiny, compact shaker grains. Teaspoon for teaspoon, therefore, sea salt is actually
less
salty than shaker salt. Weight for weight, of course, they’re identical, because any gram of sodium chloride is precisely as salty as any other. You can’t cut down on salt by eating the same weight of salt in a different form.

MAKING THE MOST OF IT

At home in your kitchen, which coarse, complexly grained sea salt should you sprinkle on your
foie gras
or venison
carpaccio
just before serving? The ones that earn the most frequent praise from chefs are the (surprise!) French salts harvested from the coastal waters of southern Brittany at Guérande or on the île de Noirmoutier or île de Ré. You will find them in several forms.
Gros sel
(big salt) and
sel gris
(gray salt) are the heavy crystals that fall to the bottom of the salt ponds and may therefore be gray with clay or algae.

In the battle of the sea salts, most connoisseurs agree that the champion is
fleur de sel
(flower of salt), the delicate crust of crystals that forms on the surface of the French ponds when the sun and wind are exactly right. Because it forms in very limited amounts and must be carefully hand-skimmed from the surface,
fleur de sel
commands the highest price and is (as a consequence, perhaps?) most highly regarded by leading chefs. Because of its fragile, pyramidal crystal shape, it does indeed produce a delightfully crunchy salt-burst when sprinkled on relatively dry foods just before serving or at the table.

But cooking with it is pointless.

YOU DON’T HAVE TO BE JEWISH

So many chefs and recipes specify the use of kosher salt. What’s different about it?

K
osher salt is misnamed; it should be called koshering salt because it is used in the koshering process, which involves blanketing raw meat or poultry with salt to purify it.

Kosher salt may be either mined or taken from the sea; nobody seems to care. Its crystals, however, must always be coarse and irregular, so they will cling to the surface of the meat during koshering. Ordinary granulated table salt would fall right off. Besides the rabbinical supervision of its manufacture, its crystal size is the only distinction between kosher salt and other salts.

Because of its coarseness, kosher salt is better used by the pinch, rather than by the shake. Pinching lets you see and feel exactly how much you’re using. That’s why most chefs use kosher salt. I keep it ever handy in a small ramekin, not only in the kitchen but on the table. I use my shaker mainly for sprinkling salt on the tails of birds.

Some people believe that kosher salt contains less sodium than granulated table salt. That’s nonsense. They’re both virtually pure sodium chloride, and sodium chloride always contains 39.3 percent sodium. Gram for gram, every edible salt is precisely as salty as any other.

There really is a difference, however, in the amount of kosher salt to use in cooking. When a recipe specifies simply “salt,” it almost always means granulated table salt: salt that consists of crystals tiny enough to fit through the holes in a saltshaker. But kosher salts, having bigger, irregularly shaped grains, don’t settle down into a teaspoon measure as compactly as table salt does. So a teaspoonful of kosher salt will contain less actual sodium chloride and you must therefore use a larger volume of it to get the same degree of saltiness. That’s what’s behind the “less sodium” myth; if you use the same number of teaspoonfuls, you are, of course, getting less salt, and hence less sodium, than in granulated salt.

By carefully weighing a cupful of each kind, I have determined the following conversion factors: For Morton’s Coarse Kosher Salt, use 1¼ times the specified volume of granulated table salt. For Diamond Crystal Kosher Salt, use exactly twice the specified volume.

It is often said that kosher salt contains no additives. And indeed, because its crystals aren’t tiny cubes like shaker salt’s, they don’t tend to stick together and don’t generally need shaker salt’s anti-caking additives. But read the labels. Diamond Crystal Kosher Salt has no additives, but Morton’s Coarse Kosher Salt does contain a tiny amount—limited by the FDA to less than thirteen ten-thousandths of 1 percent—of the anti-caking agent sodium ferrocyanide.

Ferro-what?
Relax. Even though ferrocyanide is a totally different chemical from poisonous cyanide, the labels play it safe by listing it by its less alarming name, yellow prussate of soda.

Any salt, whether from mine or sea and whether kosher or secular, may be iodized. A maximum of one-hundredth of 1 percent of potassium iodide is added as protection against the iodine-deficiency disease goiter. Iodized salt does require a special additive, however, because potassium iodide is somewhat unstable and in a warm, humid or acidic environment will decompose, its iodine content wafting off into the air. (Techspeak: The iodide is oxidized to free iodine.) To prevent this, a tiny amount—four-hundredths of 1 percent—of dextrose is often added.

Sugar in salt? Yes. Dextrose is what is known as a reducing sugar, and it prevents oxidation of the iodide to free iodine. But at the high temperatures used in baking, some of the iodide can nevertheless be oxidized to iodine, which has an acrid flavor. Many bakers therefore won’t use iodized salt in their doughs and batters.

THE OLD MILL SCHEME

Why is freshly ground salt supposed to be better than granulated salt?

I
t’s better for the people who sell those fancy salt mills and combination salt-and-pepper grinders in so-called gourmet shops. The idea seems to be that if freshly ground pepper is so much better than the powdered stuff in cans, then why not use freshly ground salt as well?

That’s a delusion. Unlike pepper, salt contains no volatile, aromatic oils to be released by grinding. Salt is solid sodium chloride through and through, so a small chunk will be absolutely identical to a large chunk in everything but size and shape. The fun of a salt grinder is that it deposits coarse little chunks, instead of tiny grains, on your food, and therefore delivers a burst of saltiness when you bite them. But it doesn’t matter how “freshly” they were ground.

WHOOPS!

When making soup, I accidentally put in too much salt. Was there anything I could have done about that? I’ve heard that raw potato will absorb the excess.

A
lmost everyone has heard that advice: Throw in some chunks of raw potato, simmer them for a while, and they will absorb some of the extra salt. But as with so many common beliefs, this one, to my knowledge, has never been tested scientifically. I took that as a challenge and set up a controlled experiment. I simmered raw potato in salty water and with the help of a chemistry professor colleague’s laboratory assistant, measured the amount of salt in the water, both before and after the potato treatment.

Here’s what I did.

I made up a couple of too-salty mock soups—actually, just plain salt water, so there would be no other ingredients to mess things up with their own saline predilections. But how salty should I make my samples? Many recipes begin with about a teaspoon of salt in four quarts of soup or stew, with more salt added “to taste” at the finish. So I made my soup sample No. 1 with one teaspoon of table salt dissolved in each quart of water, while soup No. 2 contained one tablespoon of table salt per quart of water. That’s about four and twelve times the usual recipe-starting saltiness, respectively, and perhaps two and six times the saltiness of a soup that had already been salted “to taste.”

I heated each of the two mock-soup samples to boiling, added six ¼-inch-thick slices of raw potato, simmered gently for 20 minutes in a tightly covered pan, removed the potato, and allowed the liquid to cool.

Why did I use slices of potato rather than chunks? Because I wanted to expose as much surface area to the “soup” as possible, giving the spuds every opportunity to live up to their salt-sucking reputation. And I used the same amount of potato surface area (300 square centimeters, if you must know) in both samples. Of course, I also simmered the same amounts of the two liquids in the same covered pot on the same burner. Scientists, as you must be thinking by now, are absolute maniacs about controlling all conceivable (and even some inconceivable) variables except the one they’re comparing. Otherwise, they’d never know what caused any differences they might observe. It always annoys me when a person tries something once under completely uncontrolled circumstances and then goes running around saying, “I tried it and it works.”

The concentrations of salt in the four samples—the two salt waters both before and after being simmered with the potato—were determined by measuring their electrical conductivities. The idea is that salt water conducts electricity, and the conductivity can be directly related to the salt content.

And what were the results? Did the potatoes really reduce the concentrations of salt? Well…

First let me tell you about the taste tests. I reserved the potato slices after they had been simmered in the salty waters. I had also simmered potato slices in plain water (same amounts of potato and water). My wife, Marlene, and I then tasted all of them for saltiness. She didn’t know which samples were which. Sure enough, the potato simmered in plain water was bland, the potato simmered in the one-teaspoon-per-quart water was salty, and the potato simmered in the one-tablespoon-per-quart water was much saltier. Does this mean that the potato actually absorbed salt from the “soups?”

No. All it means is that the potatoes soaked up some salt water; they didn’t selectively extract the salt from the water. Would you be surprised if a sponge placed in salt water came out tasting salty? Of course not. The
concentration
of salt in the water—the amount of salt per quart—would not be affected. So the salty taste of the potatoes proved nothing, except that for more flavor we should always boil our potatoes—and our pasta, for that matter—in salted water rather than in plain water.

Okay, now, what were the results of the conductivity measurements? Are you ready?
There was no detectable difference in the salt concentrations before and after being simmered with potato.
That is, the potato did not lower the concentration of salt at all, either in the one-teaspoon-per-quart or in the one-tablespoon-per quart “soup.” The potato trick just doesn’t work.

There are other saltiness-reduction dodges that one hears about, such as adding a little sugar, lemon juice, or vinegar to reduce the
perception
of saltiness. Are there, then, any reactions between saltiness and either sweetness or sourness that could diminish the sensation of saltiness? After all, it’s the salty
taste
that we want to diminish, even if the salt is still there.

It was time for me to go to the taste experts—the scientists at the Monell Chemical Senses Center in Philadelphia, an institution devoted to research in the complex field of human taste and smell.

First, as far as potato effects are concerned, no one I spoke with could think of any reason that a potato or its starchiness would reduce the perception of saltiness. But Dr. Leslie Stein helpfully supplied me with a 1996 review paper in the journal
Trends in Food Science & Technology
by Paul A. S. Breslin of the Monell Center on the interactions among flavors.

Can one flavor suppress another? Yes and no. It depends on both the absolute amounts and the relative amounts of the interacting flavors. “In general,” Dr. Breslin writes, “salts and acids [sour flavors] enhance each other at moderate concentrations but suppress each other at higher concentrations.” That might indicate that adding a fair amount of lemon juice or vinegar to a quite salty soup could indeed make it taste less salty. But, Breslin points out, “there are exceptions to…these generalities.” In the particular case of salt and citric acid (the acid in lemon juice), he quotes the results of one study in which citric acid reduced the perceived saltiness, one study in which the saltiness was unaffected, and two studies in which the perceived saltiness was actually increased.

So whatcha gonna do? Add lemon juice? Vinegar? Sugar? There is really no way to predict how they will act in your particular soup containing your particular amounts of salt and other ingredients. But by all means try any one of these measures before feeding the stuff to your dog.

It appears that there’s only one sure way to rescue a too-salty soup or stew: Dilute it with more stock—unsalted, of course. It would skew the flavor balance toward that of the pure stock, but that can be corrected.

EPILOGUE