Detection of carob flour in cocoa powder by direct analysis in real time-mass spectrometry (DART-MS)

Cocoa is a high value product and therefore a potential target for economic adulteration with less expensive ingredients. Carob flour is less expensive than cocoa powder and is frequently cited as a potential cocoa substitute. While carob has legitimate uses as a cocoa replacement, these characteristics also make it a potential adulterant of cocoa powder. Direct analysis in real time mass spectrometry (DART-MS) is an ambient ionization MS technique that can be used to rapidly interrogate samples. Samples of cocoa powders, carob flours, and mixtures of the two were extracted with buffer and interrogated by DART-MS. The mass spectra were used to develop models to distinguish between cocoa powder and cocoa powder adulterated with carob. A principal component-linear discriminant analysis (PCA-LDA) model was used to discriminate between cocoa powder and cocoa powder amended with 15% carob flour. The accuracy using internal validation was 100%. Using an external validation dataset, the accuracy, precision, and recall were 96.0%, 94.8%, and 97.3%, respectively. These results demonstrate that DART-MS can be used to discriminate between cocoa powder and cocoa powder adulterated with 15% carob.