Corn is the primary source of high fructose corn syrup in the US. High fructose corn syrup is a liquid alternative sweetener to sucrose that is made from corn, the “king of crops”. It is a caloric sweetener, made from ordinary corn starch, which substitutes for sugar in a wide range of manufactured products.
Corn starch composed of glucose molecules of infinite length, consists of amylose and amylopectin and requires heat, caustic soda and/or hydrochloric acid plus the activity of three different enzymes to break it down into the simple sugars glucose and fructose present in HFCS.
The production of HFCS and corn wet milling are typically an integrated process. The wet milling process separates the corn kernel into its four principal components: the germ, hull, gluten, and starch. High fructose corn syrups, as well as other corn sweeteners, utilize the corn starch slurry produced by the wet milling process as their basic input.
An industrial enzyme, α-amylase produced from Bacillus spp., hydrolyzes corn starch to short chain dextrins and oligosaccharides. Bacterial α-amylases catalyze the hydrolysis of α-1,4 glucosidic linkages and act in a random but reproducible manner to reduce the polysaccharide molecular weight. Enzymatic liquefaction requires precise control of operating conditions like percentage of solids, temperature, time, pH and calcium level to ensure efficient hydrolysis, process economics and easier downstream processing operations.
A second enzyme, glucoamylase (also called amyloglucosidase),produced from fungi such as Apergillus, breaks dextrins and oligosaccharides to the simple sugar glucose.
A glucoamylase dosage is added to produce a maximum dextrose level in 1-4 days. Reaction time is inversely related to dose, so if a given dose yields maximum dextrose in 4 days, doubling or quadrupling the dose will reduce reaction time to 2 days or 1 day, respectively.
The product of these two enzymes is corn syrup also called glucose syrup. The third and relatively expensive enzyme used in the process is glucose isomerase (also called D-glucose ketoisomerase or D-xylose ketolisomerase),that converts glucose to fructose.
Fructose is superior to all nutritive sweeteners and humectants in controlling water in frozen system. Its water activity is low as compared to sucrose, sorbitol, dextrose, mannitol, etc. which makes it a better preservative.
Manufacturing of High-Fructose Corn Syrup 
