Adventures with Almonds, Part I: The Marvelously Fragrant Hall’s Hardy Almond

This is the first part of a two-part series. I’ll publish the second, on making marzipan, shortly.

In the meantime, you might check out two articles I recently published with Mother Earth News, “Finally, a Good Thermometer for Home Preserving” and “Fun to Watch, Fun to Eat: Pickled Mixed Vegetables Brined in Glass.”

I finally got around to cracking last fall’s crop of Hall’s Hardy almonds, my biggest in the five years since I planted the tree. I had more than half a cup of nutmeats!

Hall’s Hardy is actually a peach-almond cross. But because it blooms late, resists fungal disease, and self-pollinates, it is considered the only almond variety suitable for growing in the Pacific Northwest. Or so it was considered until recently, when Jim Gilbert of One Green World introduced several Ukrainian almond varieties, all of which are said to have the same virtues as Hall’s Hardy, plus more: They are true almonds, with soft or semisoft shells. But the Ukrainian varieties are yet unproven in Oregon. For now, I’m grateful for my tiny almond harvest, especially because these almonds have something the soft-shelled true almonds almost certainly lack: the lovely flavor of almond extract—that is, the flavor of bitter almond.

Cracking a Hall’s Hardy almond is problematic. Once freed of its husk, the nut looks like a peach pit, and it’s just as thick and hard. I tried using a kind of nutcracker, meant for walnuts and pecans, that surrounds the whole nut; as you press the two arms together, the hinged central cup hugs and squeezes the nut inside until the nut breaks at the seam. I cracked two or three nuts with this cracker, and the small kernels, to my delight, turned out whole. And then the hinge sprang.

So I got out a hammer, an old bread board, and a dishtowel I’d consigned to the rag bin. With the hammer method it’s important not to use a board or a towel that you care about, because you’re bound to damage both. You place a few nuts at a time on the board, lay the towel over, and then bang, bang away. You remove the towel and collect all the nut pieces, most of them itsy-bitsy. And then you toss out a mountain of thick shell pieces and sweep the stray ones from underfoot before they damage your floor or your flesh.

By this point some of you dear readers no doubt feel alarm, and not about the dangers of stepping on nut shells. It’s my mention of the flavor of bitter almond, right? The essential oil of bitter almond is nearly pure benzaldehyde, a chemical that signifies the presence of amygdalin, which enzymes in the intestines convert to prussic acid, also known as hydrogen cyanide. And cyanide kills. Some scientists say that eating 50 bitter almonds will kill an adult; a child may die after eating only 5 to 10. Other stone-fruit kernels—apricots, peaches, and plums—contain the same flavor, the same chemicals, and the same deadly power.

Despite its toxicity, amygdalin has a long history as a medicine. In China, for example, apricot pits have been traditionally used for coughs and constipation. But amounts taken were probably miniscule before the 1950s, when amygdalin in the form of laetrile, or so-called vitamin B₁₇, became a folk treatment for cancer. In the United States, the popularity of laetrile surged after 1972, when a researcher at Memorial Sloan-Kettering Cancer Center reported that the drug inhibited secondary tumors in mice. Although other researchers were unable to confirm these results, desperate cancer patients traveled to Mexico to buy laetrile or got their amygdalin directly from stone-fruit pits—especially from apricots, whose kernels, even richer than bitter almonds in amygdalin, are used as a food flavoring in Turkey, Tunisia, and elsewhere in the Mediterranean region. At least a few children who might have survived cancer succumbed to laetrile poisoning instead.

Because some people will apparently force down the bitterest pill or nut if they think it’s good for them, bitter almonds cannot legally be sold in the United States. You can buy “pure” almond extract, which may be made from apricot or peach pits, or almond paste, probably flavored with apricot pits if not a synthetic imitation, but you can’t sell the almonds.

Some businesses do sell them, however, and those businesses include Trader Joe’s and Costco. Or so say consumers of Marcona almonds from Spain. Apparently, a bitter almond or two appear now and then in a bag of roasted Marconas, a variety with rounded kernels that are especially rich in oil. One bite of a bitter Marcona leads to spitting and gagging and a foul taste in the mouth that lasts the whole day through. Or so say these startled consumers.

This never happens with California almonds. You might occasionally taste a rancid California almond, if your nuts have been stored for too long. A rancid nut may make you spit and gag, but rancidity is not the same as bitterness.

The problem with Spanish almonds is something biologists call xenia, after a Greek word for hospitality. Xenia happens when the pollen of a plant of one genetic strain affects the seeds and fruit of the fertilized plant. This effect is distinct from the effect the pollen has on the next generation. Xenia is the reason gardeners plant their sweet corn far away from any field corn, popcorn, or ornamental corn, even if they don’t plan to save seed for planting in a subsequent year. The pollen of any of these other types of corn could turn the sweet corn starchy. In the same way, ears of white corn pollinated by yellow corn will turn out yellow, and the kernels of popcorn pollinated by sweet corn will turn out sweet and, probably, shriveled.

In the United States, all our commercial almonds are grown in California, in Central Valley orchards so extensive that beekeepers from all over the country truck in their hives for winter forage (this annual gathering of the hives is largely responsible for the rapid spread of various bee pests and diseases across the continent). Blooming California almond orchards are a lovely sight to see, as you race up or down the interstate, but they are a picture of modern, industrial farming. No doubt Spain, the world’s second largest almond producer, has orchards much like them, but I haven’t seen them. Traveling through Andalusia one winter, I got a different view of almonds in flower. Masses of pale-pink blooms were scattered here and there over the landscape. The almond trees, some small and some towering, marked old fence lines, roads that might have been buried in sand, and other past and present boundaries where the trees had grown up from seedlings and thrived without care. Almonds have been growing here since Roman times. Although bitterness in their nuts is a recessive trait, controlled by a single gene, bitter almond trees dominate in numbers because critters avoid eating their nuts—that is, their seeds—and also, apparently, because sweet almond trees are less tolerant of very dry, sandy soil.

In Spain, sweet almond orchards are mostly planted in damper, coastal areas. But sweet almonds can also grow on irrigated land or on dry land without irrigation if the scions are grafted to bitter almond trees or to peach-almond hybrids. It is in these dryland orchards, I suspect, that xenia happens. The sweet almond flowers are supposed to be fertilized by the pollen of other sweet almond varieties that bloom at the same time and are interplanted in the same orchard. (Self-pollinated varieties are yet a novelty in both Spain and California.) Every once in a while, however, a bee carries pollen from an almond tree growing wild in the fencerow or anywhere else in the vicinity; honeybees, after all, often fly two miles from the hive in search of pollen or nectar. Xenia happens when a bee brings pollen from a wild, bitter almond tree to a sweet almond tree with a recessive allele, that is, an allele—or gene variant—that when matched with another recessive allele will cause bitterness. Marcona almonds, like most of the other varieties grown in both Spain and California, is heterozygous for sweetness. From the flower where the bee deposits pollen, a bitter nut develops.

The more bitter the nut, the more amygdalin it contains. A study of Spanish almonds found amygdalin ranging from 2.16 to 157.44 milligrams per kilogram in nonbitter almonds, 523.50 to 1,772.75 milligrams per kilogram in semibitter almonds, and 33,006.60 to 5,3998.30 milligrams per kilograms in bitter almonds. The least bitter bitter almonds, then, had 210 times as much amygdalin as the most bitter nonbitter almonds. The most bitter bitter almonds had 25,000 times as much amygdalin as the least bitter nonbitter almonds.

Given that my Hall’s Hardy almonds weren’t almonds at all but an interspecies cross, I didn’t know whether to classify them as nonbitter, semibitter, or bitter. (I will continue to call my almonds almonds, however, because genetists have determined that through millennia of development peaches and almonds have crossed repeatedly.) Because of their strong aroma of benzaldehyde, I figured that the Hall’s Hardies must contain more than a little amygdalin. I found an old gardening publication from Cornell University that recommended against growing either Hall’s Hardy almonds or another hybrid variety, called Ridenhower, because of the nuts’ bitterness and possible toxicity. But I could taste barely any bitterness over the strong benzaldehyde flavor of my nuts, and I tend to be extra-sensitive to bitterness. They tasted so good, in fact—so much more interesting than California almonds!—that I would have tossed all the kernels into my mouth if I hadn’t had other plans for them.

My plan: I would make my own, no-flavor-added marzipan.