(1) Sensory examination
Coffee is brown powder, which has a special aroma due to Maillard reaction during baking, while counterfeit coffee has no or little such special aroma.
(2) Density inspection
Put the coffee powder to be tested in a test tube, add saturated sodium oxide solution and shake well. The aqueous solution of real coffee should be light amber, and the powder is completely or almost completely floating. On the other hand, if most of the powder is deposited at the bottom of the tube and the aqueous solution is dark yellow-brown, it is a substitute such as chicory and roasted granules.
(3) Qualitative test of chicory root powder.
Weigh about 10g of coffee sample to be tested, add 25ml of water to boil for 5min, then add excessive alkali or lead acetate solid, shake well for about half a minute, let stand, clarify and observe. If the upper aqueous solution is clear and colorless, it is pure coffee. If color is produced, it proves that chicory root powder is mixed.