Corn syrup

Corn syrupis a foodsyrupwhich is made from thestarchof corn/maizeand contains varying amounts of sugars:glucose,maltoseand higheroligosaccharides, depending on the grade. Corn syrup is used in foods to softentexture, add volume, preventcrystallizationof sugar, and enhance flavor. Mosttable syrupsare typically based with corn syrup. It can be processed intohigh-fructose corn syrup(HFCS) by using the enzymeD-xylose isomeraseto convert a large proportion of its glucose into sweeterfructose.
The more general termglucose syrupis often used synonymously with corn syrup, since glucose syrup in the United States is most commonly made fromcorn starch.Technically, glucose syrup is any liquid starchhydrolysateof mono-, di-, and higher-saccharidesand can be made from any source of starch: wheat,tapiocaand potatoes are the most common other sources.
Historically, corn syrup was produced by combining corn starch with dilutehydrochloric acid, and then heating the mixture under pressure. The process was invented by the German chemistGottlieb Kirchhoffin 1811. Currently, corn syrup is obtained through a multi-stepbioprocess. First, theenzymeα-amylaseis added to a mixture of corn starch and water. α-amylase is secreted by various species of thebacteriumgenusBacillusand the enzyme is isolated from the liquid in which the bacteria were grown. The enzyme breaks down the starch intooligosaccharides, which are then broken into glucose molecules by adding the enzymeglucoamylase, known also as "γ-amylase". Glucoamylase is secreted by various species of thefungusAspergillus; 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 enzymeD-xylose isomerase, an enzyme that is isolated from the growth medium of any of several bacteria.
Corn syrup is produced from number 2 yellow dent corn.Whenwet milled, about 2.3 litres of corn are required to yield an average of 947g of starch, to produce 1 kg of glucose syrup. Abushel(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 atonneof glucose syrup, or 60 bushels (1524 kg) of corn to produce oneshort ton.
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 theirdextrose equivalent(DE). Most commercially available corn syrups are approximately 1/3 glucose by weight.
Two common commercial corn syrup products are light and dark corn syrup.
Major uses of corn syrup in commercially prepared foods are as a thickener, a sweetener, and ahumectant(an ingredient that retains moisture and thus maintains a food's freshness).The primary ingredient in most brands of commercial "table syrup" is either regular corn syrup or high-fructose corn syrup, both of which are less expensive thanmaple syrup.
In the United States,tariff-rate quotasforcane sugarimports raise sugar prices;hence, domestically produced corn syrup and high-fructose corn syrup are less costly alternatives that are often used in American-made processed and mass-produced foods, candies, soft drinks, and fruit drinks.
Glucose syrupwas the primary corn sweetener in the United States prior to the expanded use ofhigh fructose corn syrupproduction in 1964.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.
If mixed withsugar,water, andcream of tartar, corn syrup can be used to makesugar glass.
Corn syrup was available atgrocery storesin the 19th century, as ageneric productsold from a barrel.In 1902, theCorn Products Refining Companyintroduced clear,bottledcorn syrup under the brand name ofKaro Syrup.In 1910, the company launched one of the largestadvertising campaignsever seen.  This included full-pageadvertisementsinwomen's magazinesand freecookbooksfull ofrecipesthat called for Karo brand corn syrup.In the 1930s, they promoted a newpecan pierecipe that featured corn syrup, followed by a similar, nut-freechess pierecipe, in a bid to drive sales.Later, they promoted it as an alternative tomaple syrupforwaffles.As cooking in the home declined in the 21st century, so that fewer people madecandiesorpiesat home, commercial sales of Karo tended to dominate over the retail sales.