to 9 pounds (3½ to 4 kg) of nut meat (about twice the weight in the shell), but the rancher can

plant 120 trees in every acre. A 100-acre orchard produces 100,000 pounds (45,000 kg) of

shelled almond meat in a modest harvest year, maybe twice as much in a good year.

When freshly harvested, all nut kernels have high moisture, between 35 and 50 percent,

of the nut meat. The tough, airtight shell protects them from animals, insects and bacteria, and

slows deterioration. But as soon as they crack the shell, the kernels are very susceptible to

microorganisms. A particularly dangerous mold produces a carcinogenic material called

aflatoxin in the kernel. Before they are processed, inspectors screen nuts and seeds for the

presence of aflatoxin. If they find more than trace, they cannot use the nuts for human

consumption. They can still press and use the oil from them because aflatoxin is not soluble in

oil and remains with the rest of the meat.

The only practical way to eliminate microorganisms in nuts is to quickly reduce their

moisture to a level too low for organisms to grow. In practice it is reduced to 4 percent within 8

to 10 hours after shelling.

Since heat improves the flavor a great deal, in food processing in the first step nearly all

nuts go through roasting.

Our Common Nuts

There are a dozen nuts and four seeds that we commonly use. Here's information about

each of them.

Almonds, the world's most popular nuts, are native to central Asia or western India. An

almond has three parts—the outer husk, the nut shell and the edible kernel inside. Almond trees

now grow in any part of the world that has a favorable warm climate. California, which is the

only place in North America with commercial almonds, produces 65 percent of the world's total.

Spain grows most of the rest.

Although there are a number of different varieties in cultivation, agronomists favor a few

for their good flavor, thin shell that is easy to crack without damaging the kernel, ease of

cultivation and harvest, good yield, and resistance to insects, bird damage and frost. Older

cookbooks mention two types of almonds, bitter and sweet, but the two are really the same. A

single dominant gene in the plant determines which flavor wins, and in the varieties we grow

today, they eliminated the bitter gene. Eating the kernel of a peach pit gives you an idea of what

bitter almonds taste like.

TASTINGS Obsolete poison

Some bitter almonds are still in demand for their essential oil (the part of oil that

contains the flavor compounds), used in food flavoring and for scents. The oil

contains a high amount of cyanide, and it is this oil of bitter almond that used to

be popular for both suicide and homicide. The oil is no longer in fashion for such

purposes, probably because guns are easier to get.

Walnut is our second most popular nut. It originated in Iran (Persia) and was originally

called Persian walnut, but the more common name today is English walnut. Of the 15 species of

edible walnuts, two are in commercially orchards—the English walnuts and the native eastern

North American black walnuts. California is the major English walnut producer in the North

America and the U.S. is the major world producer, with France and Italy next. Walnuts are

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