High-fructose corn syrup

High-fructose corn syrup (HFCS), also known as glucose–fructose syrup, and isoglucose, is a sweetener made from corn starch. As in the production of conventional corn syrup, the starch is broken down into glucose by enzymes. To make HFCS, the corn syrup is further processed with the enzyme D-xylose isomerase to convert some of its glucose into fructose. HFCS was first marketed in the early 1970s by the Clinton Corn Processing Company, together with the Japanese Agency of Industrial Science and Technology, where the enzyme was discovered in 1965.

As a sweetener, HFCS is often compared to granulated sugar, but manufacturing advantages of HFCS over sugar include that it is cheaper. "HFCS 42" and "HFCS 55" refer to dry weight fructose compositions of 42% and 55% respectively, the rest being glucose. HFCS 42 is mainly used for processed foods and breakfast cereals, whereas HFCS 55 is used mostly for production of soft drinks.

The United States Food and Drug Administration (FDA) states that it is not aware of evidence showing that HFCS is less safe than traditional sweeteners such as sucrose and honey. Uses and exports of HFCS from American producers have grown steadily during the early 21st century.

In the United States, HFCS is among the sweeteners that have mostly replaced sucrose (table sugar) in the food industry. Factors contributing to the increased use of HFCS in food manufacturing include production quotas of domestic sugar, import tariffs on foreign sugar, and subsidies of U.S. corn, raising the price of sucrose and reducing that of HFCS, creating a manufacturing-cost advantage among sweetener applications. In spite of having a 10% greater fructose content, the relative sweetness of HFCS 55, used most commonly in soft drinks, is comparable to that of sucrose. HFCS provides advantages in food and beverage manufacturing, such as simplicity of formulation, stability, and enabling processing efficiencies.

HFCS (or standard corn syrup) is the primary ingredient in most brands of commercial "pancake syrup," as a less expensive substitute for maple syrup. Assays to detect adulteration of sweetened products with HFCS, such as liquid honey, use differential scanning calorimetry and other advanced testing methods.

In the contemporary process, corn is milled to extract corn starch and an acid–enzyme process is used, in which the corn-starch solution is acidified to begin breaking up the existing carbohydrates. High-temperature enzymes are added to further metabolize the starch and convert the resulting sugars to fructose. The first enzyme added is alpha-amylase, which breaks the long chains down into shorter sugar chains (oligosaccharides). Glucoamylase is mixed in and converts them to glucose. The resulting solution is filtered to remove protein using activated carbon. Then the solution is demineralized using ion-exchange resins. That purified solution is then run over immobilized xylose isomerase, which turns the sugars to ~50–52% glucose with some unconverted oligosaccharides and 42% fructose (HFCS 42), and again demineralized and again purified using activated carbon. Some is processed into HFCS 90 by liquid chromatography, and then mixed with HFCS 42 to form HFCS 55. The enzymes used in the process are made by microbial fermentation.

HFCS is 24% water, the rest being mainly fructose and glucose with 0–5% unprocessed glucose oligomers.

The most common forms of HFCS used for food and beverage manufacturing contain fructose in either 42% ("HFCS 42") or 55% ("HFCS 55") by dry weight, as described in the U.S. Code of Federal Regulations (21 CFR 184.1866).