There is no such thing as a natural corn syrup pressed directly from corn kernels. Instead, the pulpy middle layer called cornstarch is first separated from the outer husk and the inner germ layers. The cornstarch is then stored in giant vats, where natural enzymes are added to break it down into glucose. It is these sugars that are heated and turned into a syrup.
Corn syrup is almost exactly as sweet as the granulated sugar it often replaces in recipes. It can be naturally light in color, which is often used in candymaking, or darker, which is usually used for general baking purposes. The light form may have vanilla flavoring added, while the dark syrup has a stronger natural flavor.
The advantage of this product over sugar is its resistance to crystallization. A candy lollipop made with corn syrup will retain its smooth texture, while a similar treat made from pure sugar may turn into a hardened rock candy. It also prohibits crystal formation when added to a cake or fudge mixture.
Light and dark syrup both have a balance of dextrose, fructose, malt, and glucose to keep them chemically stable, although this sweetener does have a limited shelf life compared to others. The most controversial form — high fructose corn syrup (HFCS) — is rarely sold directly to consumers, although it can be found in a majority of processed foods sold in grocery stores.
HFCS is subjected to additional processes as compared to regular corn syrup. First, three types of enzymes — alpha-amylase, glucoamylase, and glucose-isomerase — are successively added to change the starch to glucose and then fructose. Pure glucose is then added to the mixture to create the ratio of fructose to glucose that makes up the final product. There are various fructose-glucose ratios in HFCS, including 90-10, 42-43, and 55-45. Since the United States Department of Agriculture (USDA) subsidizes corn production in the US but taxes imported sugar, HFCS has become the default sweetener in many consumer food products.
Manufacturers insist that their product is just as healthy as the sucrose sugar it replaces in soft drinks, plus the savings in taxes keeps domestic food prices low. Opponents point to studies indicating serious health problems in laboratory rats fed a constant diet of this sweetener. Other sugars, like sucrose, can be processed by every cell in the human body, but fructose must be broken down in the liver. Over a lifetime, it has been suggested that the liver may become overworked by a diet heavy in this type of sugar.
Some people say that the popularity of HFCS is a matter of economics, while others point to the domestic corn industry as having a near-monopoly on the commercial sweetener market in the United States. Other countries, such as Mexico, still use sucrose sugar in their processed food products. Those who feel uneasy about the health effects of high fructose corn syrup should check the labels of foods to see if the ingredients specify the use of sugar.
