High-fructose Corn Syrup - Production

Production

HFCS was first introduced by Richard O. Marshall and Earl R. Kooi in 1957. They were, however, unsuccessful in making it viable for mass production. The industrial production process and creation was made by Dr. Yoshiyuki Takasaki at the Agency of Industrial Science and Technology of Ministry of International Trade and Industry of Japan in 1965–1970. HFCS was rapidly introduced to many processed foods and soft drinks in the U.S. from about 1975 to 1985.

High-fructose corn syrup is produced by milling corn to produce corn starch, then processing that starch to yield corn syrup, which is almost entirely glucose, and then adding enzymes that change some of the glucose into fructose. The resulting syrup (after enzyme conversion) contains approximately 42% fructose and is HFCS 42. Some of the 42% fructose is then purified to 90% fructose, HFCS 90. To make HFCS 55, the HFCS 90 is mixed with HFCS 42 in the appropriate ratios to form the desired HFCS 55. The enzyme process that changes the 100% glucose corn syrup into HFCS 42 is as follows:

1. alpha-amylase – produces shorter chains of sugars called oligosaccharides from raw cornstarch.
2. Glucoamylase – breaks the oligosaccharides down even further to yield the simple sugar glucose.
3. Xylose isomerase (aka glucose isomerase) – converts glucose to a mixture of about 42% fructose and 50–52% glucose with some other sugars mixed in.

Although both types of amylase are naturally produced by many animals (including humans), the most common method of commercial production is microbial fermentation. Xylose isomerase is not native to animals; and in standard glycolysis the glucose molecules are isomerized only after phosphorylation by Glucose-6-phosphate isomerase yielding Fructose 6-phosphate. Fructose molecules are phosphorylated by Fructokinase and enter the glycolytic pathway at this point.

While inexpensive alpha-amylase and glucoamylase are added directly to the slurry and used only once, the more costly xylose-isomerase is packed into columns and the sugar mixture is then passed over it, allowing it to be used repeatedly until it loses its activity. This 42–43% fructose glucose mixture is then subjected to a liquid chromatography step, where the fructose is enriched to about 90%. The 90% fructose is then back-blended with 42% fructose to achieve a 55% fructose final product. Most manufacturers use carbon adsorption for impurity removal. Numerous filtration, ion-exchange and evaporation steps are also part of the overall process.

The units of measurement for sucrose is degrees Brix (symbol °Bx). Brix is a measurement of the mass ratio of dissolved sucrose to water in a liquid. A 25 °Bx solution has 25 grams of sucrose per 100 grams of solution (25% w/w). Or, to put it another way, there are 25 grams of sucrose and 75 grams of water in the 100 grams of solution. The Brix measurement was introduced by Antoine Brix.

A more universal measurement of sugars, including HFCS, is called dry solids. Dry solids is defined as the mass ratio of dry sugars to the total weight of the sugar solution. Since Brix is based on the refractive index of light against a sucrose molecule it is not accurate when measuring other sugars such as glucose, maltose, and fructose.

When an infrared Brix sensor is used, it measures the vibrational frequency of the sucrose molecules, giving a Brix degrees measurement. This will not be the same measurement as Brix degrees using a density or refractive index measurement, because it will specifically measure dissolved sugar concentration instead of all dissolved solids. When a refractometer is used, it is correct to report the result as "refractometric dried substance" (RDS). One might speak of a liquid as being 20 °Bx RDS. This is a measure of percent by weight of total dried solids and, although not technically the same as Brix degrees determined through an infrared method, renders an accurate measurement of sucrose content, since the majority of dried solids are in fact sucrose.

Recently, an isotopic method for quantifying sweeteners derived from corn and sugar cane was developed which permits measurement of corn syrup- and cane sugar-derived sweeteners in humans, thus allowing dietary assessment of the intake of these substances relative to total intake.