An often perpetuated myth associated with olive oil is the "Fridge Test" - a supposedly simple home test for olive oil authenticity. The myth is so pervasive that you may even see conflicting versions of the test - some say your oil should solidify if it's real and others say it shouldn't solidify if it's real. If it just could be that easy! Unfortunately, this "test" is completely wrong and misleading. Read on to see why even the rumor-mongers are confused on this case.
Almost all oils become cloudy and eventually solidify in cold temperatures. In general, refined oils (like regular olive oil or vegetable or seed oils) solidify at a lower temperature than extra virgin olive oil. However, the time and degree of chilling required to reach the solidification stage is greatly affected by the overall chemical composition of the oil. These include the content of saturated fatty acid chains such as palmitic acid or stearic acid, which can change the melting point of triglycerides (the main component that makes up almost 98% of all oils and fats) and other compounds in oil, as well as the presence of natural waxes.
The profile of an olive oil, and extra virgin olive oil in particular, is incredibly diverse as the composition of the oil is influenced by so many natural factors that vary by region, season and type of olive. This includes:
The olive variety
The seasonal growing conditions
The latitude of the country of origin
The time of harvest
The processing methods
All of these factors affect the final profile of the olive oil, and even olives from the same trees can produce oil that varies from year to year. Because olives are a fruit, the skin has natural waxes that protect the fruit as it grows. The evidence of these waxes can be traced back in the end product. These natural waxes are not harmful but the range is variable and some suppliers even refrigerate and filter the oil to remove visible waxes for appearance to produce a more polished oil which also affects the oil's congealing temperature. Finally, to achieve and maintain a consistent flavor profile, some producers may blend multiple varieties of extra virgin olive oil from different olive cultivars or regions. This also affects the time and degree of cold required to get to the solidification phase.
There is no simple, magical home test to verify the authenticity of olive oil. Extra virgin olive oil will crystallize and/or congeal under a variety of time and temperature exposures. All these differences make extra virgin olive oil very special. Forget the fridge and instead focus on enjoying the wide variety of flavors that can be found among extra virgin olive oils.