High fructose corn syrup (HFCS) refers to a group of corn syrups which have undergone enzymatic processing in order to increase their fructose content and are then mixed with pure corn syrup (100% glucose) to reach their final form. The typical types of HFCS are: HFCS 90 (most commonly used in baked goods) which is approximately 90% fructose and 10% glucose; HFCS 55 (most commonly used in soft drinks) which is approximately 55% fructose and 45% glucose; and HFCS 42 (most commonly used in sports drinks) which is approximately 42% fructose and 58% glucose.
The process by which HFCS is produced was first developed by Richard O. Marshall and Earl R. Kooi in 1957 This makes it useful to manufacturers as a possible substitute for sucrose (table sugar) in soft drinks and other processed foods. According to the scientific definition of sugar, fructose and glucose are types of sugar, rather than substitutes for sugar, even though in common usage sugar usually refers specifically to sucrose. HFCS 90 is sweeter than sucrose as fructose is sweeter than glucose, while HFCS 42 is not as sweet as sucrose.

Comparison to other sugars
Cane sugar is relatively pure sucrose. Sucrose is a disaccharide, as opposed to glucose and fructose, which are monosaccharides. Each molecule of sucrose is composed of one unit each of fructose and glucose linked together with a relatively weak glycosidic bond. A molecule of sucrose (with a chemical formula of C₁₂H₂₂O₁₁) can be broken down into a molecule of glucose (C₆H₁₂O₆) plus a molecule of fructose (also C₆H₁₂O₆ — an isomer of glucose) in a weakly acid environment. Sucrose is broken down during digestion into fructose and glucose through hydrolysis by the enzyme sucrase, by which the body regulates the rate of sucrose breakdown. Without this regulation mechanism, the body has less control over the rate of sugar absorption into the bloodstream.
Because sucrose can be broken down into fructose and glucose, some people say that sucrose is composed "50% glucose and 50% fructose." This, strictly speaking, is incorrect, because the fructose and glucose in sucrose are linked together and thus it is a different molecule. On the other hand, because sucrose is broken down into its constituent monosaccharides - namely fructose and glucose - in weakly acidic environments by a process called inversion, it is not incorrect to describe its constituents as 50% glucose and 50% fructose. This same process occurs in the stomach and in the small intestine during the digestion of sucrose into fructose and glucose. According to two published reports (both supported by industry - Pepsico, the American Beverage Institute and the Corn Refiners Association) sucrose is metabolized by the body like a mixture of 50% glucose and 50% fructose with no detectable difference from HFCS .

Cane sugar
Honey is a mixture of different types of sugars, water, and small amounts of other compounds. Honey typically has a fructose/glucose ratio similar to HFCS 55, as well as containing some sucrose and other sugars. Honey, HFCS and sucrose have the same number of calories having approximately 4 kcal per gram of solid; Honey and HFCS both have about 3 kcal per gram in liquid form .

Honey
High-fructose corn syrup is produced by milling corn to produce corn starch then processing that corn starch to yield corn syrup that is almost entirely glucose, and then adding enzymes that change the glucose into fructose. The resulting syrup (after enzyme conversion) contains approximately 90% fructose and is HFCS 90. To make the other common forms of HFCS (HFCS 55 and HFCS 42) the HFCS 90 is mixed with 100% glucose corn syrup in the appropriate ratios to form the desired HFCS. The enzyme process that changes the 100% glucose corn syrup into HFCS 90 is as follows:
While inexpensive alpha-amylase and glucoamylase are added directly to the slurry and used only once, the more costly glucose-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 approximately 90%. The 90% fructose is then back-blended with 42% fructose to achieve a 55% fructose final product. Most manufacturers use carbon absorption for impurity removal. Numerous filtration, ion-exchange and evaporation steps are also part of the overall process.

Cornstarch is treated with alpha-amylase to produce shorter chains of sugars called oligosaccharides.
Glucoamylase breaks the sugar chains down even further to yield the simple sugar glucose.
Glucose isomerase converts glucose to a mixture of about 42% fructose and 50–52% glucose with some other sugars mixed in. Production
The units of measurement for sugars including HFCS are degrees Brix (symbol °Bx). Brix is a measurement of the mass ratio of dissolved sugars to water in a liquid. A 25 °Bx solution has 25 grams of HFCS per 100 grams of liquid (25% w/w). Or, to put it another way, there are 25 grams of sugar and 75 grams of water in the 100 grams of solution. The Brix measurement was introduced by Antoine Brix.
When an infrared Brix sensor is used, it measures the vibrational frequency of the High Fructose Corn Syrup 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. The advent of in-line infrared Brix measurement sensors have made measuring the amount of dissolved HFCS in products economical using a direct measurement. It also gives the possibility of a direct volume/volume measurement.
Recently [4]an isotopic method for quantifying sweeteners derived from corn and sugar cane was developed by Jahren et al. that 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.

Measuring Concentration of HFCS

Sweetener consumption patterns
Because of a system of price supports and sugar quotas imposed since May 1982, importing sugar into the United States is prohibitively expensive. High fructose corn syrup, derived from corn, is more economical since the American price of sugar is artificially far higher than the global price of sugar

USA: 32.4 kg
EU: 40.1 kg
Brazil: 59.7 kg
Australia: 56.2 kg In the United States
In the European Union(EU), HFCS, known as isoglucose, has been subject to production quotas under the sugar regime since 1977. Production of isoglucose in the EU has been limited to 507,000 metric tons, equivalent to about 2%-3% of sugar production. Therefore, wide scale replacement of sugar has not occurred in the EU. In Japan, HFCS consumption accounts for one quarter of total sweetener consumption.

International markets
Some controversy has come up over the use of HFCS as a food additive as manufacturers begin to utilize HFCS in an increasing variety of foods, such as breads, cereals, soft drinks, and condiments.

Controversy

Main article: Agricultural policy American farm lobby
Overconsumption of sugars has been linked to adverse health effects, and most of these effects are similar for HFCS and sucrose. There is a striking correlation between the rise of obesity in the US and the use of HFCS for sweetening beverages and foods, but it is not clear whether this is coincidence or a causal relationship. Some critics of HFCS do not claim that it is any worse than similar quantities of sucrose would be, but rather focus on its prominent role in the overconsumption of sugar, for example encouraging overconsumption through its low cost.
Possible differences in health effects between sucrose and HFCS could arise from the fact that glucose and fructose in sucrose are bound in a disaccharide or from the 10% difference in fructose content. At least in beverages, sucrose often separates into glucose and fructose before the beverage is consumed anyway, according to an industry-funded study
In summary, the evidence in peer-reviewed publications shows that overconsumption of fructose, whether from sucrose or HFCS, may be responsible for many of the adverse effects associated with overconsumption of sugars in general. However, industry-funded studies, also in peer-reviewed publications, have shown that the differences between the metabolic effects of HFCS and sucrose are small. Nonetheless, there are many people who believe that the health effects of HFCS are significantly worse than those of sucrose, based on anecdotal evidence or studies that don't directly examine this difference. [5] It can be difficult to find direct support for these claims in peer-reviewed journals; it is also difficult to find direct evidence against them in studies not supported by the beverage industry.

Labeling as "natural"
Some beverage manufacturers have returned to cane sugar as a sweetener, maintaining that there is a noticeable difference in taste.
Jones Soda announced that the company will launch its 12 ounce canned soda (January 2007) sweetened with pure cane sugar instead of high fructose corn syrup. The brand will be called Jones Pure Cane Soda and will be sold as a 12 ounce can package. As of March 2007, a 12 ounce bottle of Jones Pure Cane Soda Root Beer lists in its ingredients "inverted cane sugar", which seems to mean the same thing as inverted sugar syrup, which, like HFCS, is a mixture of fructose and glucose.
Goose Island sodas also use pure sugar and they market this to have a more pure flavor. Their market slogan is "Made with 100% real sugar for better taste."
Steaz sodas and energy drinks use only organic cane sugar produced using a "single-crystallization process preserves the original flavor... without the use of additives, preservatives, or animal by-products."
Jolt Cola was originally sweetened with sugar, and marketed with the slogan "All the sugar and twice the caffeine." A later reformulation, though, replaced sugar with HFCS.
Vernors was originally sweetened with stevia from 1866 to 1991 and had a "deliciously different" taste. Stevia was replaced with HFCS when the FDA banned it in 1991 in a controversial decision.
Some Coca-Cola products have started to use sucrose as indicated by the ingredient list clearly marked on the outside of the box. This is not widespread and is dependent on individual processing plants. Coca-Cola does not have an official statement at this time on whether they are or are not using sucrose.
One independent Dr Pepper bottler in Dublin, Texas never switched, giving "Dublin Dr Pepper" a unique taste. Other bottlers have since followed suit, sometimes offering both HFCS and cane sugar sweetened versions in the same market.
Blue Sky Beverage Company (a fully-owned part of the Hansen Beverage Company) has two lines of sodas that do not use HFCS as a sweetener. Blue Sky Real Sugar is a line of sodas that use sugar as a sweetener, and Blue Sky Organic Sodas use organic cane juice as a sweetener.