วิธีเช็คคุณภาพของน้ำมันมะกอกแท้หรือเทียม... https://www.quora.com/How-do-you-know-if-your-olive-oil-is-really-olive-oil-and-not-a-substitute-Is-there-a-test How do you know if your olive oil is really olive oil and not a substitute? Is there a test? Or follow this steps: Get yourself a laser that has a violet or green light. A laser, though, always works best. Point the source of light to a glass containing the oil you want to test. The cointainer must be colourless. If it really is extra virgin oil, you will see something like that... Real true olive oil will show green laser turning orange color inside the real olive oil, if it is fake olive oil the green laser color will not change it will remain green...