Are McDonald's fries even made of potatoes? Why are there 17 ingredients in its fries? The fast-food giant lifted the veil on its fry production line and ingredient list Tuesday to dispel myths about one of its most popular items in two new videos. The fry tour is the latest in a series of segments with former MythBusters star Grant Imahara aimed at addressing rumors about the quality of its food and improving transparency as it struggles to turn around its U.S. business.

Turns out, there are real spuds in the fries. As for that 17 number, that's a myth. There are really 19 ingredients.

In addition to different oils, the list includes several chemicals that perform various functions, including ones that adds flavor, an anti-foaming agent that keeps oil from splattering, another aimed at keeping "the potatoes from going gray" and preservatives, Imahara explains. Read MoreMcDonald's shows how McNuggets arereally made Imahara also takes a tour at Simplot, which supplies potatoes to McDonald's USA, with Koko Neher, a production planner there. Whole potatoes travel on a conveyor belt before being shot through a high-pressure water tube through a grate at 60 to 70 miles per hour. Read MoreNearly9 in 10 diners willing to pay more for this Next up is the "ingredient dip." "This is the ingredient dip, where we control the color, and we're adding dextrose – all natural sugar – to make sure that we get a consistent color no matter what time of the year it is," said Neher, adding that it also puts in sodium acid pyrophosphate to control "graying after freezing."