1. Sensory inspection: First observe the appearance of Danny's coffee. The real Danny coffee should be brown powder with special aroma produced by baking. If the appearance or smell of the product is obviously inconsistent with these characteristics, it may be a fake.
2. Density check: put Denny coffee powder into a test tube, add saturated sodium oxide solution and shake well. The real Denny Coffee solution should be light amber, and most or all of the powder will float. If most of the powder is deposited at the bottom of the test tube and the aqueous solution is dark yellow-brown, it may be a substitute for chicory or roasted grain.
Please note that although these methods are helpful to distinguish the authenticity of Danny's coffee, they cannot guarantee the accuracy of 100%. If you suspect that the purchased Denny coffee is fake, it is recommended to contact the supplier or professional organization for further testing.