[header] How to know when sesame oil is rancid [title] Check your oil for a dark, amber color. [step] Sesame oils that appear darker in color than usual-a deep amber hue as opposed to a light golden color-are often rancid. Compare the color of your oil to images of sesame oil online to determine whether or not your oil is rancid. 
[title] Feel the bottle to see if it's sticky. [step] A sticky residue will develop on the outside of a rancid oil container.