To meet Paul Schrade, a tall, white-haired 77-year-old with a gently bemused smile, you'd never suspect that he's obsessed with a poisonous nut. Mention the bitter almond, however, and the retired union organizer won't stop talking about how--on a culinary tour of Sicily in 1990--he fell in love with its powerful, unique flavor, which gives marzipan and almond milk their characteristic taste. Even after he was told that raw bitter almonds contained a form of cyanide and were illegal in the Unites States, Schrade was fascinated.
"I thought, 'European chefs make good use of bitter almonds for cooking and baking--why shouldn't we?'" he says.
Through his second career as a bakery consultant and forager for Campanile restaurant, Schrade sought to spur a revival of the ancient Mediterranean flavoring in California. Undeterred, or perhaps intrigued, by the nut's sinister reputation--spread by mystery tales in which the detective sniffed the odor of bitter almonds on a cyanide victim's breath--he sleuthed relentlessly for sources and information.
He learned that most of the original wild species of almonds were bitter, but that, as the nuts came into cultivation thousands of years ago, farmers began concentrating their crops toward sweet types, the kind grown today in California.
A recessive gene causes bitter almond trees to produce in their shoots, leaves and kernels a toxic compound called amygdalin, which serves as a chemical defense against being eaten. When amygdalin is moistened, it splits into edible benzaldehyde, which provides an intense almond aroma and flavor, and deadly hydrocyanic acid, a fast-acting inhibitor of the respiratory system.
The lethal dose of raw bitter almonds depends on the size of the nuts, their concentration of amygdalin and the consumer's sensitivity. But scientists estimate that a 150-pound adult might die from eating between 10 and 70 raw nuts, and a child from ingesting just a few.
In any case, although it may be safe for most adults to nibble a raw bitter almond to experience its intense flavor, that would be unpleasant to most people. The nuts are not meant to be eaten as a snack food like regular almonds: They're used as a spice, like nutmeg or cinnamon.
Schrade, who studied organic chemistry at Yale, learned that because hydrocyanic acid vanishes into the air when heated, cooking destroys the poison in bitter almonds and allows them to lend their flavor to a wide range of dishes, both traditional and modern.
In the course of his explorations, Schrade found several California chefs eager to cook with bitter almonds. At the center of this informal network is Tim Woods of Echo restaurant in Fresno, famed for his zealous use of local ingredients.
Since bitter almonds are usually not available commercially, he harvests his nuts from nearby wild and backyard trees, and uses them to add a pleasing bite to the richness of bread pudding with caramel and to stone-fruit cobblers. He also shares his supplies with Sean Lippert, formerly chef of Across the Street in New York, for her bitter almond granita, and with Judy Rodgers of Zuni Cafe in Berkeley and Kim Boyce, pastry chef of Campanile, who both use the nuts to flavor panna cotta and ice cream.
Until recent decades, most Mediterranean almond orchards were grown from seed, and the shuffling of genes resulted in a mix of bitter almond trees among the sweet. Growers liked to keep a few bitter trees around because they helped to pollinize the sweet varieties. The inclusion of bitter nuts gave snackers occasional unpleasant surprises, but they deepened the flavor of marzipan, almond milk and glazes for cakes. In Italy, bitter almond paste was traditionally used to make crisp amaretti cookies, and bitter almond extract flavored amaretto liqueur. In Greece, bitter almonds are used in soumada, a sweet syrup.
There's little large-scale cultivation of bitter almonds left in Spain and Italy, mostly just scattered trees remain, but it is still possible to buy raw bitter almonds at European specialty markets. Morocco and Iran now lead in commercial production of bitter almonds.
In the United States, the lack of clear information about bitter almonds' legal status has squelched their cultivation, trade and use. No stores regularly stock bitter almonds, so cooks seeking them have had to rely, like Woods, on seedling trees growing wild along streams, roads and railroad tracks.
"I don't know if I should sell them or not," says Bill Fujimoto, owner of Monterey Market in Berkeley, which carries bitter almonds occasionally. "I don't leave them out on the counter. I sell them only when people who know bitter almonds ask me for some."