Since most adulterations usually include the addition of "fillers" such as grain, cereal, coffee twigs, and corn - their identification is becoming more difficult. Luckily, roasted corn samples contain high concentrations of vitamin E, making it a prime "fingerprint" for adulteration. In laboratory tests scientist found that one brand of Brazilian coffee contained almost 9% corn.
Although preliminary, scientists believe the method is promising. Paper to be presented in the Journal of Agricultural and Food Chemistry on August 8, 2007, "Gamma-Tocopherol as a Marker of Brazilian Coffee (Coffea arabica L.) Adulteration by Corn".