McDonald's french fries are made from whole potatoes that are peeled, cut into french fries and then partially fried before they are packaged and shipped to the chain's restaurants.
A video from McDonald's Canada explains the process in more detail.
The video shows McDonald's potatoes being harvested from farms and then sent to a processing plant, where they are washed, peeled and cut.
"Once the potatoes are cut, we push the strips to a blancher to remove the natural sugars from the strips," Mario Dupuis, the production manager for McCain, a fries supplier for McDonald's Canada, says in the video. "This will prevent some variation in our color once we re-cook the product.
"Following the blanching process we add a a dextrose solution to have that nice even coat that we see in the restaurants. We also add an ingredient to our strips to make sure that we prevent the graying of our product throughout the process."
Next, moisture is removed from the strips before they are fried, frozen, and packaged for shipping.
Here are the ingredients in the fries, as listed on McDonald's website: Potatoes, vegetable oil (canola oil, soybean oil, hydrogenated soybean oil, natural beef flavor, citric acid), dextrose, sodium acid pyrophosphate (maintains color), salt. Once the fries arrive at the restaurants, they are prepared in vegetable oil (canola oil, corn oil, soybean oil, hydrogenated soybean oil and dimethylpolysiloxane.