Difference between high fructose corn syrup and invert sugar?

Functionally there is no difference. Both are ~50% glucose and ~50% fructose (HFCS can vary between 92% fructose and 42% fructose, most HFCS used in food is between 42% and 55% fructose, the balance being glucose).

The following descriptions are by necessity simplified, but will serve to demonstrate the important aspects of the production of the two products.

Invert sugar is sucrose (a molecule of fructose bonded to a molecule of glucose) mixed with a bit of water and heated. The water and heat cause a splitting of the sucrose molecule called hydrolysis. Often catalysts are added to speed the splitting, acid being a common catalyst (lemon juice, cream of tartar, etc.). The resulting syrup is free glucose and fructose in a bit of water.

HFCS is made by taking corn starch (starch is a long chain of glucose molecules) and splitting it up into glucose. This is done by enzymes. The result from this is corn syrup, much like the corn syrup you can purchase in a supermarket. To turn the corn syrup into high fructose corn syrup it is mixed with a another enzyme which changes the glucose into fructose. The resulting syrup is usually 92% fructose. Fructose is much sweeter than glucose (~1.8 times as sweet). To make a syrup that resembles the sweetness of invert sugar the 92% (HFC92) HFCS is mixed with corn syrup to get a final percentage of fructose around 42%-55% (HFC42 and HFC55). All the enzymes used in the process are removed before the syrup is used in food.

While the two processes are different, it is obvious that the final product is virtually, and metabolically, identical.

Jonathan Davey

A.O.S. Culinary Arts, B.S. Food Science