To look at many cookbooks, you'd think olive oil and canola oil were identical twins separated at birth. Countless recipes call for "extra-virgin olive oil or canola oil," as if the two were interchangeable.
This implied equivalence is odd. Extra-virgin olive oil is cold-pressed from a fruit that has been cultivated for more than 7,000 years, with no refining beyond filtration. Canola oil is refined with heat, pressure, solvents, and bleach, and comes from the seed of a plant that's younger than the Rolling Stones.
The canola plant was conceived when demand for rapeseed oil plummeted in the late 1940s, and the Canadian rapeseed industry began seeking and creating new markets for its product. Since the Industrial Revolution, rapeseed oil has been an important component of lubricants for ships and steam engines, because unlike most oils it sticks to wet metal. During World War II the U.S. built a lot of ships, and so needed lots of rapeseed oil, but couldn't get it from traditional suppliers in Europe and Asia. The Canadian rapeseed industry, which had been relatively small, exploded to fill the gap, and played an important role in the allied naval effort, becoming rich and powerful in the process.
But rapeseed oil demand waned when the war ended, and thus began an intensive program to breed a rapeseed edible to humans. The Holy Grail was a strain with dramatically lower levels of erucic acid and glucosinolates, which are the main culprits behind rapeseed oil's foul flavor, and according to some research, toxic effects. READ MORE