Corn syrup isn't a useful ingredient anyway. It only exists in the US due to corn subsidies. I would be more concerned about the difference in flour between UK and US. That would change a "perfect" recipe significantly.
> Incidentally, if you want the absolute chewiest, most uniformly textured cookies, try replacing some of the white sugar with corn syrup, a sugar that is even more hygroscopic. Corn syrup is so darn powerful, in fact, that even a small amount of it will completely alter the texture of your cookie. In the cookies above, the batch on the left was made with 5 ounces each of white and brown sugar. The batch on the right was made with 5 ounces of brown sugar, 4 ounces of white sugar, and 1 ounce of corn syrup. A substitution of only 10%.
Yes, that's correct. Granulated sugar (sucrose) is fructose and glucose. Corn syrup is glucose syrup made from corn. HFCS is made to simulate sucrose by adding fructose to corn syrup.
In the US we like to market things based on what they don't contain (unsalted butter, unsmoked provolone, etc), so glucose syrup is sold as as "0g High Fructose Corn Syrup, aka light corn syrup with _real_ vanilla":
HFCS is actually more like invert syrup then, which consists of glucose and fructose separately, like honey. Sucrose consists of glucose and fructose chemically bonded together.
