Editors' Note Appended
DAN PEARSON was working in northern Peru two years ago with his stepson Brian Horsely, supplying gear and food to mining companies, when something caught his eye.
“We were in a hidden mountain valley of the Marañón River and saw some strange trees with football-size pods growing right out of their trunks,” Mr. Pearson said by telephone last week. “I knew nothing about cacao, but I learned that’s what it was.”
It was, he would learn after sending samples of seeds and leaves to the Agricultural Research Service of the United States Department of Agriculture, one of the rarest, most prized varieties of cacao.
“The DNA of this material is pure Nacional,” said Dr. Lyndel Meinhardt, a scientist with the service. “These are very rare.”
Until the early 20th century, Nacional, a member of the Forastero family, one of the three main genetic categories of cacao, was widely grown in Ecuador, then the world’s largest cacao producer. But it succumbed to disease, which even cross-breeding could not resist. Some Nacional still grows in Ecuador, though most is not pure. At least one chocolate company, Kallari, says it uses it in blends.
But with the help of the Swiss chocolate expert Franz Zeigler, beans that Mr. Pearson and his stepson buy are being made into slabs of pure Nacional chocolate. “The magnitude of this find is bigger than anything I have known,” Mr. Zeigler said.
The chocolate is intense, with a floral aroma and a persistent mellow richness. Its lack of bitterness is remarkable.
One reason may be that Nacional cacao has a rare and precious characteristic: some of the beans are white, not the usual purple, and those from the Marañón Canyon are about 40 percent white. White beans, which Dr. Meinhardt said have fewer bitter anthocyanins, produce a more mellow-tasting, less acidic chocolate. Dr. Meinhardt said white beans are mutations that happen when trees are left undisturbed for hundreds of years.
A cacao pod is filled with sweet, whitish, viscous pulp embedded with seeds. Inside these seeds are the beans. You cannot easily tell which pods or seeds will have white beans, but Mr. Pearson said, without revealing more, that he has figured it out.
Chocolate made from 100 percent white beans is extremely expensive. (When roasted the beans turn brown and they are unrelated to “white chocolate.”)
Cacao is thought to have originated in the rain forests at the source of the Amazon and Orinoco Rivers and then gradually dispersed northward. What surprised Dr. Meinhardt the most about Mr. Pearson’s cacao was that it was growing at an altitude above 3,500 feet, while cacao rarely grows above 2,000 feet.
In the canyon, 186 farmers are growing pure Nacional. The beans are transported to a town several hours away, where they are dried, fermented and roasted, then sent to Lima and shipped to Switzerland. The chocolate is processed there by a company recommended by Mr. Zeigler, which Mr. Pearson did not want to name. The beans are made into what they call Fortunato No. 4, a 68-percent bittersweet couverture, a high-cocoa butter chocolate that’s easy to use.
They have 15 tons of it in slabs. A company in Switzerland and one each in Germany, Canada and the United States (Moonstruck Chocolatier, of Portland, Ore.) are making candies and bars with the chocolate.
At Moonstruck, the exclusive American retailer for the chocolate, Julian Rose, the chocolatier, is coating pure Nacional beans with pure Nacional chocolate. These will be introduced this weekend at the Fancy Food Show in San Francisco, and are sold as Fortunato Tumbled Beans at moonstruckchocolate.com ($12 for 3.5 ounces; bars of Peruvian Fortunato are $12 for 2 ounces). Mr. Rose said the flavor of this chocolate is so refined that it does not need vanilla, commonly added to chocolate, to round it out.
At the Institute of Culinary Education in New York, Michelle Tampakis, the director of advanced pastry studies, said the chocolate was extremely smooth when melted, with a full-bodied, nutty flavor that was not bitter.
Mr. Zeigler, who visited the canyon with Mr. Pearson last year, said he had a “Jurassic Park feeling” about the experience. “And the discovery of the white beans tops the whole thing,” he said. “I have no doubt this chocolate will be up there with the very best in the world.”

Editors' Note: January 21, 2011

An earlier version of this article was accompanied by a photograph showing one of the cacao pods. After a reader raised questions, editors learned that the picture had been digitally altered by a marketing firm that supplied it, which worked for one of the companies involved in using the cacao. (The alteration made the pod appear purely yellow, rather than the mottled yellow-and-green of the original picture.) Had editors known of the alteration, the picture would not have been used.

This article has been revised to reflect the following correction:
Correction: January 12, 2011

An earlier version of this article misstated the prices of the Fortunato Tumbled Beans and Peruvian Fortunato chocolate bars.

This article has been revised to reflect the following correction:
Correction: January 19, 2011

An article last Wednesday about Fortunato No. 4, a chocolate made from cacao beans that were recently found growing in Peru, referred incorrectly to a component of the chocolate. It is high in cocoa butter, not butterfat.