Glucose syrup, also known as confectioner's glucose, is a

syrup In cooking, a syrup (less commonly sirup; from ar, شراب; , beverage, wine and la, sirupus) is a condiment that is a thick, viscous liquid consisting primarily of a solution of sugar in water, containing a large amount of dissolved sugars ...

made from the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

of starch.

Glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

is a sugar.

Maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...

(corn) is commonly used as the source of the starch in the US, in which case the syrup is called " corn syrup", but glucose syrup is also made from

potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern Unit ...

es and

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

, and less often from

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

and

cassava ''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively cultivated ...

.^p. 21 Glucose syrup containing over 90%

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

is used in

industrial fermentation Industrial fermentation is the intentional use of fermentation in manufacturing products useful to humans. In addition to the mass production of fermented foods and drinks, industrial fermentation has widespread applications in chemical industry. ...

, but syrups used in confectionery contain varying amounts of

, maltose and higher

oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sug ...

s, depending on the grade, and can typically contain 10% to 43% glucose. Glucose syrup is used in foods to sweeten, soften texture and add volume. By converting some glucose in corn syrup into fructose (using an

enzymatic Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. ...

process), a sweeter product,

high fructose corn syrup High-fructose corn syrup (HFCS), also known as glucose–fructose, isoglucose and glucose–fructose syrup, is a sweetener made from corn starch. As in the production of conventional corn syrup, the starch is broken down into glucose by enzy ...

can be produced. Glucose syrup was first made in 1811 in Russia by

Gottlieb Kirchhoff Gottlieb Sigismund Constantin Kirchhoff (19 February 1764 – 14 February 1833) was a Russian chemist of German origin. In 1792–1802, Assistant Director and then Director of the Head Pharmacy at Saint Petersburg. Corresponding member (1807� ...

using heat and sulfuric acid.

Types

Depending on the method used to

hydrolyse Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

the starch and on the extent to which the hydrolysis reaction has been allowed to proceed, different grades of glucose syrup are produced, which have different characteristics and uses. The syrups are broadly categorised according to their dextrose equivalent (DE). The further the hydrolysis process proceeds, the more

reducing sugar A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reacti ...

s are produced, and the higher the DE. Depending on the process used, glucose syrups with different compositions, and hence different technical properties, can have the same DE.

Confectioner's syrup

The original glucose syrups were manufactured by

acid hydrolysis In organic chemistry, acid hydrolysis is a hydrolysis process in which a protic acid is used to catalyze the cleavage of a chemical bond via a nucleophilic substitution reaction, with the addition of the elements of water (H2O). For example, in th ...

of corn starch at high temperature and pressure. The typical product had a DE of 42, but quality was variable due to the difficulty of controlling the reaction. Higher DE syrups made by acid hydrolysis tend to have a bitter taste and a dark colour, due to the production of hydroxymethylfurfural and other byproducts.^p. 26 This type of product is now manufactured using a continuous converting process and is still widely used due to the low cost of acid hydrolysis. The sugar profile of a confectioner's syrup can also be mimicked by

enzymatic hydrolysis In biochemistry, enzymatic hydrolysis is a process in which enzymes facilitate the cleavage of bonds in molecules with the addition of the elements of water (i.e. hydrolysis). It plays an important role in the digestion of food. It may be used t ...

. A typical confectioner's syrup contains 19% glucose, 14% maltose, 11%

maltotriose Maltotriose is a trisaccharide (three-part sugar) consisting of three glucose molecules linked with α-1,4 glycosidic bonds. It is most commonly produced by the digestive enzyme alpha-amylase (a common enzyme in human saliva) on amylose in starc ...

and 56% higher

molecular mass The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...

s.^p. 464 A typical 42 DE syrup has about half the sweetness of sugar,^p. 71 and increasing DE leads to increased sweetness, with a 63 DE syrup being about 70%, and pure dextrose (100 DE) about 80% as sweet as sugar.^p. 71

High-maltose glucose syrups

By using β-amylase or fungal

α-amylase α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose: :Endohyd ...

, glucose syrups containing over 50% maltose, or even over 70% maltose (extra-high-maltose syrup) can be produced.^p. 465 This is possible because these enzymes remove two glucose units (i.e. one maltose molecule) at a time from the end of the starch molecule. High-maltose glucose syrup has a great advantage in the production of

hard candy A hard candy (American English), or boiled sweet (British English), is a sugar candy prepared from one or more sugar-based syrups that is heated to a temperature of 160 °C (320 °F) to make candy. Among the many hard candy varieti ...

: at a given moisture level and temperature, a maltose solution has a lower

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

than a glucose solution, but will still set to a hard product. Maltose is also less humectant than glucose, so candy produced with high-maltose syrup will not become sticky as easily as candy produced with a standard glucose syrup.^p. 81

Commercial preparation

Irrespective of the feedstock or the method used for hydrolysis, certain steps are common to the production of glucose syrup:

Preparation

Before conversion of starch to glucose can begin, the starch must be separated from the plant material. This includes removing fibre and protein (which can be valuable by-products, for example wheat or maize

gluten Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grai ...

^p. 22). Protein produces off-flavours and colours due to the

Maillard reaction The Maillard reaction ( ; ) is a chemical reaction between Amino acid, amino acids and Reducing sugar, reducing sugars that gives browned food its distinctive flavor. Searing, Seared steaks, fried dumplings, cookies and other kinds of biscuits, b ...

, and fibre is insoluble and has to be removed to allow the starch to become hydrated. The plant material also needs to be ground as part of this process to expose the starch to the water.

Soaking

The starch needs to be swelled to allow the enzymes or acid to act upon it. When grain is used, sulfur dioxide is added to prevent spoilage.

Gelatinization

By heating the ground, cleaned feedstock, starch gelatinization takes place: the intermolecular bonds of the starch molecules are broken down, allowing the hydrogen bonding sites to engage more water. This irreversibly dissolves the starch granule, so the chains begin to separate into an amorphous form. This prepares the starch for hydrolysis.

Hydrolysis

Glucose syrup can be produced by

, enzyme hydrolysis, or a combination of the two. Currently, a variety of options are available. Formerly, glucose syrup was only produced by combining corn starch with dilute

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

, and then heating the mixture under pressure. Currently, glucose syrup is mainly produced by first adding the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

α-

amylase An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of ...

to a mixture of corn starch and water. α-amylase is secreted by various species of the

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

Bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum '' Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacill ...

''; the enzyme is isolated from the liquid in which the bacteria are grown. The enzyme breaks the starch into

s, which are then broken into glucose molecules by adding the enzyme

glucoamylase Glucan 1,4-α-glucosidase (EC 3.2.1.3, glucoamylase, amyloglucosidase', γ-amylase, lysosomal α-glucosidase, acid maltase, exo-1,4-α-glucosidase, glucose amylase, γ-1,4-glucan glucohydrolase, acid maltase, 1,4-α-D-glucan glucohydrolase) is an ...

, known also as "γ-amylase". Glucoamylase is secreted by various species of the

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...

Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Mic ...

''; the enzyme is isolated from the liquid in which the fungus is grown. The glucose can then be transformed into fructose by passing the glucose through a column that is loaded with the enzyme D-xylose isomerase, an enzyme that is isolated from the growth medium of any of several bacteria.

Clarification

After hydrolysis, the dilute syrup can be passed through columns to remove impurities, improving its colour and stability.

Evaporation

The dilute glucose syrup is finally evaporated under vacuum to raise the solids concentration.

Uses

Its major uses in commercially prepared food products are as a thickener, sweetener, and humectant (an ingredient that retains moisture and thus maintains a food's freshness). Glucose syrup is also widely used in the manufacture of a variety of candy products. In the United States, domestically produced corn syrup and high-fructose corn syrup (HFCS) are often used in American-made processed and mass-produced foods, candies, soft drinks and fruit drinks to increase profit margins. 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 glucose into fructose. The resulting syrup is sweeter and more soluble. Corn syrup is also available as a retail product. Glucose syrup is often used as part of the mixture that goes into creating

fake blood Theatrical blood, stage blood or fake blood is anything used as a substitute for blood in a theatrical or cinematic performance. For example, in the special effects industry, when a director needs to simulate an actor being shot or cut, a wide ...

for films and television. Blood mixtures that contain glucose syrup are very popular among independent films and film makers, as it is cheap and easy to obtain.

References

External links

How corn is turned into corn syrup.

{{Authority control Corn-based sweeteners Starch Syrup