Chocolate is produced from cocoa beans, dried and partially fermented seeds of the tropical tree Theobroma cacao L. This plant exists in different varieties, ranging from fine-flavor species used to produce premium chocolate to common cacao varieties yielding low quality chocolate. Common cocoa species, however, often contaminate premium ones, thereby affecting the quality of high-value chocolate products.

Dapeng Zhang, Nanjing Agricultural University, China, and co-workers reported a system to authenticate high quality cocoa varieties. The scientists demonstrated that it is possible to determine the genetic identity of single cocoa beans by analyzing single nucleotide polymorphisms (SNPs), namely variations occurring in DNA sequences among different biological samples. The analysis of the SNPs of cocoa beans DNA provided fingerprints of different cocoa varieties, thereby enabling the researchers to unambiguously distinguish low quality species from premium quality ones.

• Accurate Determination of Genetic Identity for a Single Cacao Bean, Using Molecular Markers with a Nanofluidic System, Ensures Cocoa Authentication,
  Wanping Fang, Lyndel W. Meinhardt, Sue Mischke, Cláudia M. Bellato, Lambert Motilal, Dapeng Zhang,
  J. Agric. Food Chem. 2014, 62, 481–487.
  DOI: 10.1021/jf404402v