Recently I posted about fake ingredients in foods, esp. olive oils. Then a few days ago, a friend passed on a tip to verify if it's really unadulterated olive oil. Put some EVOO in a small container and refrigerate for 2 days. If it's unadulterated, the EVOO will solidify.
I had 3 brands of First Cold-Pressed EVOO on hand, so I tried the technique. The Frantoia I use only as a finishing oil passed with flying colors. The other 2, also marked first cold-pressed EVOO, failed miserably. One was Zoe (from Spain), and the other is Bella-Famiglia (from Italy).
What kind of oil the last two have been cut with is anybody's guess. The GMO canola or soybean are about the cheapest oils, but none of the vegetable oils are very healthy for us.
On the other hand, there is some disagreement about the reliability of the refrigerator test, although I happen to think it's the best method available to me at home.