Glucose syrup, also known as confectioner's glucose, is a syrup made from the hydrolysis of starch. Glucose is a sugar. Maize (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 potatoes and wheat, and less often from barley, rice and cassava. [1] p. 21 [2]
Glucose syrup containing over 90% glucose is used in industrial fermentation, [3] but syrups used in confectionery contain varying amounts of glucose, maltose and higher oligosaccharides, depending on the grade, and can typically contain 10% to 43% glucose. [4] 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 process), a sweeter product, high fructose corn syrup can be produced.
Glucose syrup was first made in 1811 in Russia by Gottlieb Kirchhoff using heat and sulfuric acid. [5]
Depending on the method used to hydrolyse 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 sugars 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.
The original glucose syrups were manufactured by acid hydrolysis 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. [1] p. 26 This type of product is now manufactured using a continuous converting process [6] 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. [6] A typical confectioner's syrup contains 19% glucose, 14% maltose, 11% maltotriose and 56% higher molecular mass carbohydrates. [7] p. 464 A typical 42 DE syrup has about half the sweetness of sugar, [1] 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. [1] p. 71
By using β-amylase or fungal α-amylase, glucose syrups containing over 50% maltose, or even over 70% maltose (extra-high-maltose syrup) can be produced. [7] 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: at a given moisture level and temperature, a maltose solution has a lower viscosity 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. [1] p. 81
Irrespective of the feedstock or the method used for hydrolysis, certain steps are common to the production of glucose syrup:
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 [1] p. 22). Protein produces off-flavours and colours due to the Maillard reaction, 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.
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.
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.
Glucose syrup can be produced by acid hydrolysis, 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, and then heating the mixture under pressure. Currently, glucose syrup is mainly produced by first adding the enzyme α-amylase to a mixture of corn starch and water. α-amylase is secreted by various species of the bacterium Bacillus ; the enzyme is isolated from the liquid in which the bacteria are grown. The enzyme breaks the starch into oligosaccharides, which are then broken into glucose molecules by adding the enzyme glucoamylase, known also as "γ-amylase". Glucoamylase is secreted by various species of the fungus Aspergillus ; 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. [8] [9]
After hydrolysis, the dilute syrup can be passed through columns to remove impurities, improving its colour and stability.
The dilute glucose syrup is finally evaporated under vacuum to raise the solids concentration.
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). [10] 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. [10]
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 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.
Glucose is a sugar with the molecular formula C6H12O6. 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, using energy from sunlight, where it is used to make cellulose in cell walls, the most abundant carbohydrate in the world.
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc).
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double sugars, are molecules made of two bonded monosaccharides; common examples are sucrose, lactose, and maltose. White sugar is a refined form of sucrose. In the body, compound sugars are hydrolysed into simple sugars.
Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed by the gut directly into the blood of the portal vein during digestion. The liver then converts both fructose and galactose into glucose, so that dissolved glucose, known as blood sugar, is the only monosaccharide present in circulating blood.
Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula C
12H
22O
11.
Corn syrup is a food syrup which is made from the starch of corn/maize and contains varying amounts of sugars: glucose, maltose and higher oligosaccharides, 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 not the same as high-fructose corn syrup (HFCS), which is manufactured from corn syrup by converting a large proportion of its glucose into fructose using the enzyme D-xylose isomerase, thus producing a sweeter substance.
Marshmallow is a confectionery made from sugar, water and gelatin whipped to a solid-but-soft consistency. It is used as a filling in baking or molded into shapes and coated with corn starch. This sugar confection is inspired by a medicinal confection made from Althaea officinalis, the marsh-mallow plant.
Maltose, also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two-unit member of the amylose homologous series, the key structural motif of starch. When beta-amylase breaks down starch, it removes two glucose units at a time, producing maltose. An example of this reaction is found in germinating seeds, which is why it was named after malt. Unlike sucrose, it is a reducing sugar.
Inverted sugar syrup, also called invert syrup, invert sugar, simple syrup, sugar syrup, sugar water, bar syrup, syrup USP, or sucrose inversion, is a syrup mixture of the monosaccharides glucose and fructose, that is made by hydrolytic saccharification of the disaccharide sucrose. This mixture's optical rotation is opposite to that of the original sugar, which is why it is called an invert sugar.
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.
Mizuame is a sweetener from Japan. A clear, thick, sticky liquid, it is made by converting starch to sugars. Mizuame is added to wagashi to give them a sheen, eaten in ways similar to honey, and can be a main ingredient in sweets. Some Mizuame are produced in a very similar fashion to corn syrup and are very similar in taste.
Brown rice (malt) syrup, also known as rice syrup or rice malt, is a sweetener which is rich in compounds categorized as sugars and is derived by steeping cooked rice starch with saccharifying enzymes to break down the starches, followed by straining off the liquid and reducing it by evaporative heating until the desired consistency is reached. The enzymes used in the saccharification step are supplied by an addition of sprouted barley grains to the rice starch or by adding bacterial- or fungal-derived purified enzyme isolates.
Maltitol is a sugar alcohol used as a sugar substitute and laxative. It has 75–90% of the sweetness of sucrose and nearly identical properties, except for browning. It is used to replace table sugar because it is half as energetic, does not promote tooth decay, and has a somewhat lesser effect on blood glucose. In chemical terms, maltitol is known as 4-O-α-glucopyranosyl-D-sorbitol. It is used in commercial products under trade names such as Lesys, Maltisweet and SweetPearl.
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 enzymes. To make HFCS, the corn syrup is further processed by D-xylose isomerase to convert some of its glucose into fructose. HFCS was first marketed in the early 1970s by the Clinton Corn Processing Company, together with the Japanese Agency of Industrial Science and Technology, where the enzyme was discovered in 1965.
Hydrogenated starch hydrolysates (HSHs), also known as polyglycitol syrup, are mixtures of several sugar alcohols. Hydrogenated starch hydrolysates were developed by the Swedish company Lyckeby Starch in the 1960s. The HSH family of polyols is an approved food ingredient in Canada, Japan, and Australia. HSH sweeteners provide 40 to 90% sweetness relative to table sugar.
A hard candy, or boiled sweet, 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 varieties are stick candy such as the candy cane, lollipops, rock, aniseed twists, and bêtises de Cambrai. "Boiled" is a misnomer, as sucrose melts fully at approximately 186 °C. Further heating breaks it into glucose and fructose molecules before it can vaporize.
Critics and competitors of high-fructose corn syrup (HFCS), notably the sugar industry, have for many years used various public relations campaigns to claim the sweetener causes certain health conditions, despite the lack of scientific evidence that HFCS differs nutritionally from sugar. The HFCS industry has tried to respond to these campaigns with their own efforts.
High-maltose corn syrup (HMCS) is a food additive used as a sweetener and preservative. The majority sugar is maltose. It is less sweet than high-fructose corn syrup and contains little to no fructose. It is sweet enough to be useful as a sweetener in commercial food production, however. To be given the label "high", the syrup must contain at least 50% maltose. Typically, it contains 40–50% maltose, though some have as high as 70%.