SEC. 402. [342] A food shall be deemed to be adulterated

In any proceeding under this subparagraph, the United States shall bear the burden of proof on each element to show that a dietary supplement is adulterated. The court shall decide any issue under this paragraph on a de novo basis. 

Adulterated Meat (USDA)

Adulteration is addressed under the "Definitions" section of the Meat Inspection Act

21 USC Sec. 601. Definitions