Also known as HFCS
High fructose corn syrup is produced from corn starch. Starch is a polymer made of glucose molecules linked into long chains. Corn starch is first treated with the enzymes alpha-amylase and glucoamylase. These break the starch down to glucose. The glucose is then treated with another enzyme, glucose isomerase, that can reversibly convert glucose to fructose. At the end of this step, the mixture usually contains about 42% fructose and 58% glucose. A separation step produces a syrup containing about 90% fructose, and this can be blended with the 42% fructose material to make the 55% fructose syrup that is widely used in beverage manufacture.
High fructose corn syrup has a clean sweet taste. It is a mixture of fructose and glucose, both of which also have a very clean sweet taste. The level of sweetness depends on the extent to which glucose has been converted to fructose: glucose is less sweet than sucrose (table sugar), and fructose is more sweet. But the commonly used forms have fructose:glucose ratios of 55:45 or 42:58, so they end up being about as sweet as sucrose.
All carbohydrates (sugars), including fructose and glucose, provide approximately 4 calories per gram.
High fructose corn syrup is a viscous liquid. Because of the fructose content, high fructose corn syrup does not tend to form crystals, as sucrose syrups do.
High fructose corn syrup is a mixture of fructose and glucose. It is fully digestible and easily metabolized by the human body. The primary concern with HFCS is one of overconsumption.
A given weight of HFCS is comparable in sweetness to the same weight of sucrose. Fructose is somewhat sweeter than sucrose, and glucose is somewhat less sweet than sucrose.