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ScienceShot: A Genetic Test for High-Quality Chocolate

To help keep the makers of high-quality chocolate from being duped with inferior ingredients, researchers have developed a genetic test that can tell a premium cacao bean from a mediocre impostor. Beans of the cacao plant, the source of cocoa butter and cocoa powder used to make chocolate, can differ widely in appearance, even within the same seed pod (beans within pod, image). So, visually discriminating beans from an exceptional variety from average-tasting beans can be difficult. That poses problems for people in charge of quality control, because unscrupulous bean merchants have ample opportunity to mix in cheaper beans among their premium products. Enter genetics. By analyzing DNA extracted from 30-milligram samples of the seed coat of a cacao bean (which is genetically identical to the tree it comes from), it’s possible to verify whether the bean belongs to a specific variety of cacao. Using the newly developed test, which looked at 48 different genetic markers, researchers were able to discriminate 30 authentic samples of a high-priced cacao variety called Fortunato No. 4 from five other varieties grown in and near Peru and 18 others grown worldwide, they report today in  the Journal of Agricultural and Food Chemistry. Although DNA analyses can be performed relatively quickly, separating a seed coat from its bean is now rather time-consuming, the researchers say. Future research will focus on streamlining the tests and on developing a technique that can be used to analyze bulk cocoa powder.

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