Someone earlier got it wrong. Traditional corn syrup is made with mild acids and heat.
Not since 1967.
The process for converting starches into sugars was first developed in Japan in the 800s using arrowroot. In 1811, the Russian chemist G.S.C. Kirchoff rediscovered this process when he heated potato starch in a weak solution of sulfuric acid to produce several starch-derived sweeteners, including dextrose. In the United States, this acid conversion method was adapted to corn starch in the mid-1800s and the first corn sweeteners were produced in a plant in Buffalo, New York, in 1866. This process remained the principal source of corn syrup until 1967, when the enzyme conversion method for producing high fructose corn syrup was commercialized. At first, this was a batch process requiring several days. In 1972, a continuous enzyme conversion process was developed that reduced the time to several minutes or hours.
Read more: http://www.madehow.com/Volume-4/Corn-Syrup.html#ixzz6m6qS6wyn