High fructose corn syrup

Structural formulae of fructose (left) and glucose (right)

A high fructose corn syrup (HFCS)—also called glucose-fructose in Canada^[1] and isoglucose, glucose-fructose syrup or fructose-glucose syrup in Europe^[2][3][4]—is any of a group of corn syrups that have undergone enzymatic processing to convert some of its glucose into fructose to produce a desired sweetness. In North America, because of its low price compared to sucrose (table sugar), HFCS is commonly used in processed foods.^[5]

HFCS consists of 24% water and the rest sugars. The most widely used varieties of HFCS are: HFCS 55 (mostly used in soft drinks), approximately 55% fructose and 42% glucose; and HFCS 42 (used in beverages, processed foods, cereals, and baked goods), approximately 42% fructose and 53% glucose.^[6][7] HFCS-90, approximately 90% fructose and 10% glucose, is used in small quantities for specialty applications^[8] but primarily is used to blend with HFCS 42 to make HFCS 55 (see below).

Use as a replacement for sugar

In the United States, HFCS is among the sweeteners that have primarily replaced sucrose (table sugar) in the food industry.^[9] Factors for this include governmental production quotas of domestic sugar, subsidies of U.S. corn, and an import tariff on foreign sugar, all of which combine to raise the price of sucrose to levels above those of the rest of the world, making HFCS cheapest for many sweetener applications.^[10][11] The relative sweetness of HFCS 55 is comparable to that of table sugar (sucrose), a disaccharide of fructose and glucose,^[12] (HFCS 90 is sweeter than sucrose and HFCS 42 is less sweet than sucrose) while, being a liquid, HFCS is easier to blend.^[13]

Comparison to other sweeteners

Cane and beet sugar

Cane sugar and beet sugar are both relatively pure sucrose. While glucose and fructose (the two components of HFCS) are monosaccharides, sucrose is a disaccharide composed of glucose and fructose linked together with a relatively weak glycosidic bond. The fact that sucrose, glucose, and fructose are unique, distinct molecules complicates the comparison between cane and beet sugar (sucrose) and HFCS. 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 acidic environment by a process called inversion.^[14] Sucrose is broken down during digestion into a mixture of 50% fructose and 50% glucose through hydrolysis by the enzyme sucrase. People with sucrase deficiency cannot digest (break down) sucrose and thus exhibit sucrose intolerance.^[15]

Honey

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. Like HFCS, honey contains water and has approximately 3 kcal per gram. Because of its similar sugar profile and lower price, HFCS has been used illegally to "stretch" honey. As a result, checks for adulteration of honey no longer test for higher-than-normal levels of sucrose, which HFCS does not contain, but instead test for small quantities of proteins that can be used to differentiate between HFCS and honey.^[16]

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, primarily because the glucose-isomerizing activity they discovered required arsenate, which is highly toxic to humans.^[17] An industrially feasible glucose (xylose) isomerase, which did not require arsenate ion for its catalytic activity, was first discovered by Kei Yamanaka, Kagawa University, Japan, in 1961.^[18][19] The industrial production process was refined by Yoshiyuki Takasaki at the Agency of Industrial Science and Technology of Ministry of International Trade and Industry of Japan in 1965–1970.

HFCS is produced by milling corn (maize) to produce corn starch, processing that starch to yield corn syrup, which is almost entirely glucose, and then adding enzymes that convert some of the glucose into fructose. This resulting syrup contains approximately 42% fructose, and is aptly named HFCS 42. HFCS 42 can be further purified into a 90% fructose syrup, 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 enzymes involved in converting corn starch into HFCS 42 are:

1. alpha-amylase, which produces shorter chains of sugars called oligosaccharides from raw cornstarch.
2. Glucoamylase, which breaks the oligosaccharides down even further to yield the simple sugar glucose.
3. Xylose isomerase (aka glucose isomerase), which 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 to 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.^[20]

Sweetener consumption patterns

Historical

Prior to the development of the worldwide sugar industry, dietary fructose was limited to only a few items. Milk, meats, and most vegetables, the staples of many early diets, have no fructose, and only 5–10% fructose by weight is found in fruits such as grapes, apples, and blueberries. Molasses and common dried fruits have a content of less than 10% fructose sugar. From 1970 to 2000 there was a 25% increase in "added sugars" in the U.S.^[21]

United States

US sweetener consumption, 1966–2012, in dry pounds. Note: the line labeled "Total" indicates total corn sweeteners, not total sweetener consumption.

The use of HFCS in the United States is partially attributable to government tariffs that maintain domestic sugar prices at above the global price and subsidies to corn growers that lower the cost of the primary ingredient in HFCS, corn. Since 1797 there have been a system of sugar tariffs and sugar quotas in the United States that maintains the price of imported sugar at levels up to twice the global price.^[22][23] Industrial users of sugar were continually looking for cheaper replacements and HFCS was rapidly adopted as a lower cost sweetener when a food grade version became available in the 1970s. HFCS derived from corn is more economical than sugar in the United States.^[24][25]

HFCS is more stable, particularly in acidic beverages, and its liquid form is easier to transport, handle, and mix than granulated sucrose.^[26] Soft drink makers such as Coca-Cola and Pepsi use sugar in other nations, but switched to HFCS in the U.S. in 1984.^[27] Large corporations, such as Archer Daniels Midland, lobby for the continuation of government corn subsidies.^[28]

Other countries, including Mexico, typically use sugar in soft drinks. Some Americans seek out Mexican Coca-Cola in ethnic groceries because they prefer the taste compared to Coca-Cola in the U.S. which is made with HFCS.^[29][30] Kosher for Passover Coca-Cola sold in the U.S. around the Jewish holiday also uses sucrose rather than HFCS and is also highly sought after by people who prefer the original taste.^[31]

Consumption of HFCS in the U.S. has declined since it peaked at 37.5 lb (17.0 kg) per person in 1999. The average American consumed approximately 27.1 lb (12.3 kg) of HFCS in 2012,^[32] versus 39.0 lb (17.7 kg) of refined cane and beet sugar.^[33][34] "

European Union

In the European Union (EU), HFCS, known as isoglucose in sugar regime, is subject to a production quota. In 2005, this quota was set at 303,000 tons; in comparison, the EU produced an average of 18.6 million tons of sugar annually between 1999 and 2001.^[35] Wide-scale replacement of sugar with HFCS has not occurred in the EU. For labeling purpose, syrup which is predominantly glucose, like HFCS 42, is called Glucose-Fructose Syrup (GFS), while syrup which is predominantly fructose, like HFCS 55, called Fructose-Glucose Syrup (FGS).

Japan

In Japan, HFCS accounts for one quarter of total sweetener consumption.^[36] In the Japanese Agricultural Standard it is called 異性化糖 ("isomerized sugar"). If a syrup contains more than 50% glucose, it is called ブドウ糖果糖液糖 ("glucose fructose syrup"); if syrup contains 50% to 90% fructose, it is called 果糖ブドウ糖液糖 ("fructose glucose syrup"); and if syrup is more than 90% fructose, it is called 高果糖液糖 ("high fructose syrup").

Health

Health concerns have been raised about HFCS, which allege contribution to obesity, cardiovascular disease, diabetes,^[37] and non-alcoholic fatty liver disease.^[38] Critics of the extensive use of HFCS in food sweetening argue that the highly processed substance is more harmful to humans than regular sugar, contributing to weight gain by affecting normal appetite functions.^[39]

The Corn Refiners Association disputes these claims and maintains that HFCS is comparable to table sugar.^[40] Studies by the American Medical Association state that "it appears unlikely that HFCS contributes more to obesity or other conditions than sucrose", but welcome further independent research on the subject.^[41] Further reviews in the clinical literature have disputed the links between HFCS and obesity,^[42] type 2 diabetes,^[43] and metabolic syndrome,^[42] and some food and beverage industry experts have concluded that HFCS is no different from any other sugar in relationship to these diseases.^[42]

HFCS has been classified as a "generally recognized as safe" (GRAS) by the U.S. Food and Drug Administration since 1976.^[44]

Although HFCS and sucrose have similar amounts of fructose, HFCS is the primary source of added sweeteners in the U.S. While the growth of fructose consumption in many developed nations coincides with the increase of prevalence of obesity, medical research to date is inconclusive, with contradictory conclusions presented by various research teams.^[45] The consensus supported by many health professionals and nutrition experts points at an overall excessive use of carbohydrates, particularly sugar-sweetened beverages, that lead to weight gain, due to a decreased effect on satiety.^[46]

While high-fructose corn syrup contains all-natural ingredients, the processing sequence may involve the use of artificial and synthetic agents.^[47] This may also include corn syrup derived from GMO corn crops in US produced HFCS.^[47]

The use of food-grade hydrochloric acid in the processing of corn syrup has given rise to speculations that HFCS can be a source of inorganic mercury, depending on how it is manufactured. A 2009 study found that out of 20 samples of HFCS collected from three separate manufacturers, 11 did not contain detectable levels of mercury (detection limit 0.005 μg mercury/g) while 9 of 20 samples did contain mercury. Eight of the 9 samples containing mercury had levels of mercury ranging from 0.065 μg to 0.570 μg mercury/g HFCS. The samples of HFCS that did not contain mercury "were likely manufactured using caustic soda produced by a membrane chlor-alkali plant which does not use mercury in its manufacturing process."^{[48][49][50][51]} The food industry no longer uses conventional chemical hydrolysis for the manufacture of HFCS, but instead a multi-step bioprocess that uses bacterial enzymes.

Apiculture

In apiculture in the United States, HFCS has become a sucrose replacement for honey bees. In 2009, a study by Leblanc et al. found that at temperatures above 45 °C (113 °F) HFCS rapidly forms hydroxymethylfurfural, which is toxic to the honey bees being fed HFCS.^[52] In 2012, a study by Chensheng Lu et al. found symptoms of colony collapse disorder (CCD) in beehives fed HFCS that the researchers laced with levels of a pesticide hypothesized to have been present in HFCS feed since 2006.^[53]

A 2013 study by Wenfu Mao and colleagues from the University of Illinois at Urbana–Champaign report that "constituents found in honey, including p-coumaric acid, pinocembrin, and pinobanksin 5-methyl ether, specifically induce detoxification genes." They found that adding p-coumaric acid to a diet of sucrose increases mid-gut metabolism of coumaphos, a widely used in-hive pesticide used for controlling Varroa destructor mites, by approximately 60%. Since p-coumaric acid is a major component of pollen, it is part of the natural diet of honey bees and may help regulate immune and detoxification processes. They conclude: "Using honey substitutes, including HFCS, may thus compromise the ability of honey bees to cope with pesticides and pathogens and contribute to colony losses."^[54][55]

Public relations

There are various public relations issues with HFCS, including with its labeling as "natural", with its advertising, with companies that have moved back to sugar, and a proposed name change to "corn sugar". In 2010 the Corn Refiners Association applied to allow HFCS to be renamed "corn sugar", but were rejected by the United States Food and Drug Administration in 2012.^[56]

See also

• High maltose corn syrup
• High fructose corn syrup and health

Further reading

Litchfield, Ruth (2008). High Fructose Corn Syrup—How sweet it is. Ames, Iowa: Iowa State University Extension and Outreach. Retrieved 2013-03-01. 

References

External links

• Sugar, The Bitter Truth
• High fructose corn syrup at DMOZ
• Not only Sugar is Sweet, article in FDA Consumer published in 1991

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