What is Corn Syrup?

Michael Pollick
Michael Pollick

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.

A bottle of corn syrup, which is often used for baking and making candy.
A bottle of corn syrup, which is often used for baking and making candy.

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.

Spoonful of corn syrup.
Spoonful of corn syrup.

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.

Corn syrup is made when corn starch is broken down into glucose.
Corn syrup is made when corn starch is broken down into glucose.

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.

Corn syrup is used as a sweetener for caramel popcorn.
Corn syrup is used as a sweetener for caramel popcorn.

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.

Corn syrup is used in candy production.
Corn syrup is used in candy production.

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.

Many soft drinks are sweetened with high fructose corn syrup.
Many soft drinks are sweetened with high fructose corn syrup.
Michael Pollick
Michael Pollick

A regular wiseGEEK contributor, Michael enjoys doing research in order to satisfy his wide-ranging curiosity about a variety of arcane topics. Before becoming a professional writer, Michael worked as an English tutor, poet, voice-over artist, and DJ.

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Discussion Comments


All corn syrup is no good. It has traces of mercury in it. Use real sugar. If people stopped buying it the makers would get the hint.


To everybody saying not to eat corn because it is genetically altered, I'm not saying you're wrong, but every plant is now genetically altered as to withstand different climates, have different tastes and more varieties as well as have a longer shelf life. Not only does it make them produce more/ longer and at different periods, but it also makes things available to different countries for a lower price.

And how do they genetically alter plants? It's been done for hundreds of years, much longer than lab existence! Most were done (and still are) using grafting. Look it up!


Sugar cane is grown in Florida and Texas as well as Hawaii.

About 90 percent of the corn grown in the US is genetically modified to withstand high doses of glyphosate and pesticides and in fact, the corn seed itself contains glyphosate.

One could substitute a simple sugar syrup or honey in place of corn syrup. If you choose to use corn syrup, you may as well be opening that locked (hopefully) cabinet and measure out some weed killer.


Corn syrup can be used as a sweetener too, not just HFCS. Once you are off sucrose and fruit sweetened sweets, the corn syrup is surprisingly sweet.


The article confuses “corn syrup” and “high fructose corn syrup” (HFCS). So does the current Wiki article on the topic. A cook using corn syrup in a recipe will not, and should not, be using HFCS. Corn syrup is added for its thickening properties and for the “mouth feel” which can not be gotten with HFCS. Straight HFCS would be terrible for making candy (or pancake syrup).

The only bottle I have is labeled Karo brand Corn Syrup, but I am sure there are a number of other brands. The short description offered on this page is generally correct for the manufacture of HFCS.


Whenever I eat foods with HFCS, my IBS acts up and I need to use immodium. My sensitivity to HFCS is on my medical records, but I had a hard time getting the dietetic staff to check all my foods during a hospital stay in 2010.


I have corn allergies and corn syrup is in everything. It forces me to eliminate all processed food which is extremely hard but very healthy.


I'm weary of using anything made from corn, when a large portion of corn in America is genetically altered. How does that affect the body's ability to break them down and what side effects do they cause?


Dextrose and glucose are the same thing. Sucrose is half glucose and half fructose. Metabolically, there's not a whole lot of difference between HFCS and sucrose.

It'd be good to know what the percent composition of corn syrup is. Some sites seem to hint that it's primarily, if not completely, glucose.


Corn syrup: It is not the sugar that causes the obesity problems, it is the extremely high sulfite level in the corn syrup from the extraction process that causes the body to be unable to utilize the sugar as an energy source.


@anon77562: It is not about jobs, it is about money. Corn is subsidized now. It takes less corn syrup than sugar to sweeten a product, and it is used in almost everything that is processed. Heck, we have so much of it we send it to other countries as aid. Remember a few years ago when Africa did not want GMO corn we had donated to them?

Monsanto owns a monopoly over the crops such as corn, soybeans, and cotton. It is no wonder that these plants dominate commercial industries. Monsanto loves rounding up farmers who have infringed the copyright on their patented seeds. (What another great way to make money!)


the US grows cane sugar in Hawaii.


To anon74196: Our government subsidizes the use and production of corn syrup because it keeps millions of Americans employed. Think of the production of HFCS. The farmer grows the corn (majority of the midwest). Then the corn is sent to processing plants which also employs Americans.

We grow corn in America. We do not grow sugar cane. If you'd rather distribute our cash more evenly to Latin American and tropical countries that can grow sugarcane, go for it. Persuade the government that's a cheaper and better idea.

As far as the health concerns of HFCS, use moderation.

HFCS and sugar share many qualities but have a slightly different chemical structure. Be smart about it.

A glass of sweet tea with nine teaspoons of raw sugar in it is just as unhealthy as a soda with nine teaspoons of HFCS in it.


stupid people eating a stupid diet. don't eat crap and you will feel better.


Another way our so-called "free market" is manipulated by our so-called "free republic" government. Our government subsidizes the use of an unhealthy high fructose corn syrup, then blames the "free market" insurance companies for raising their rates too high, then takes over health care for Americans. Sounds like we are the idiots for allowing this to happen. I'm moving to New Zealand.


Is 43/43 the same thing as HFCS?


No, you can't use golden syrup in place of corn syrup. They are nothing alike and would change the flavor of the recipe completely.


can you use golden syrup instead of corn syrup?


if you didn't have corn syrup in your cupboard and you were cooking something with corn syrup in the ingredients, can you use something else as a substitute, like golden syrup?


is Karo Syrup a HFCS? Would honey be good as a substitute for HFCS?


High fructose corn syrup entered into the American market in the 1970s in response to a corn surplus. It was a cheap alternative to sugar that not only had a longer shelf life, but also helped corn farmers that were suffering against competing imports.

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