Corn syrup is a food
syrupIn cooking, a syrup is a thick, viscous liquid consisting primarily of a solution of sugar in water, containing a large amount of dissolved sugars but showing little tendency to deposit crystals...
, which is made from the
starchStarch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
of
maizeMaize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
and contains varying amounts of
maltoseMaltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....
and higher
oligosaccharideAn oligosaccharide is a saccharide polymer containing a small number of component sugars, also known as simple sugars...
s, depending on the grade. Corn syrup is used in foods to soften texture, add volume, prevent crystallization of sugar, and enhance flavor. Corn syrup is distinct from high-fructose corn syrup (HFCS), which is created when corn syrup undergoes enzymatic processing, producing a sweeter compound that contains higher levels of
fructoseFructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
.
The more general term
glucose syrupGlucose syrup is a food syrup, made from the hydrolysis of starch. Maize is commonly used as the source of the starch in the USA, in which case the syrup is called "corn syrup", but glucose syrup is also made from other starch crops, including potatoes, wheat, barley, rice and cassavap.21...
is often used
synonymSynonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...
ously with corn syrup, since glucose syrup is in the US most commonly made from corn starch. Technically, glucose syrup is any liquid starch
hydrolysateHydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
of mono-, di-, and higher-saccharides and can be made from any source of
starchStarch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
;
wheatWheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
,
tapiocaTapioca is a starch extracted Manihot esculenta. This species, native to the Amazon, Brazil, Colombia, Venezuela, Cuba, Puerto Rico, Haiti, the Dominican Republic, Honduras, and most of the West Indies, is now cultivated worldwide and has many names, including cassava, manioc, aipim,...
and potatoes are the most common other sources.
Commercial preparation
Corn syrup is produced from number 2 yellow dent corn. When
wet milledWet-milling is a process in which feed material is steeped in water, with or without sulphur dioxide, to soften the seed kernel in order to help separate the kernel’s various components...
, about 2.3 litres of corn are required to yield an average of 947g of starch, to produce 1 kg of glucose or dextrose syrup. A
bushelA bushel is an imperial and U.S. customary unit of dry volume, equivalent in each of these systems to 4 pecks or 8 gallons. It is used for volumes of dry commodities , most often in agriculture...
(25 kg) of corn will yield an average of 31.5 pounds (14.3 kg) of starch, which in turn will yield about 33.3 pounds (15.1 kg) of syrup. Thus, it takes about 2,300 litres of corn to produce a
tonneThe tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
of glucose syrup, or 60 bushels (1524 kg) of corn to produce one
short tonThe short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...
.
The viscosity and sweetness of the syrup depends on the extent to which the hydrolysis reaction has been carried out. To distinguish different grades of syrup, they are rated according to their
dextrose equivalentDextrose equivalent is a measure of the amount of reducing sugars present in a sugar product, relative to glucose, expressed as a percentage on a dry basis. For example, a maltodextrin with a DE of 10 would have 10% of the reducing power of dextrose , while sucrose, with a DE of 120, would have...
(DE).
Uses
Its major uses in commercially prepared foods are as a thickener, sweetener and
humectantA humectant is a hygroscopic substance. It is often a molecule with several hydrophilic groups, most often hydroxyl groups, but amines and carboxyl groups, sometimes esterified, can be encountered as well; the affinity to form hydrogen bonds with molecules of water is crucial here.Since...
(an ingredient that retains moisture and thus maintains a food's freshness).
In the United States, cane sugar quotas raise the price of sugar; hence, domestically produced corn syrup and high-fructose corn syrup are less expensive alternatives that are often used in American-made processed and mass-produced foods, candies, soft drinks and fruit drinks to help control cost.
Glucose syrup was the primary corn sweetener in the United States prior to the expanded use of HFCS production. HFCS is a variant in which other enzymes are used to convert some of the glucose into fructose. The resulting syrup is sweeter and more soluble. Corn syrup is also available as a retail product.
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