High-fructose corn syrup
High-fructose corn syrup (HFCS) is a product of maize (corn) that has been processed into a sugar syrup with a higher than normal fructose-glucose ratio. The process for making high-fructose corn syrup using enzymes was first developed in the 1950s, and by the mid-1970s HFCS was widely used as a sweetener in sodas and other processed foods. This use is heaviest in the United States, where corn is subsidized and imported sugar is subject to tariffs. In other countries, particularly those countries where "corn" is a generic term for any cereal crop, HFCS is called "glucose-fructose syrup."
There is significant controversy[Who?] over its use in food, both in terms of whether or not it is "natural" and whether or not it is linked to the rising rates of obesity and type 2 diabetes that coincided with its increased use during the 1970s.
How it's made
To make high-fructose corn syrup, you must first make regular corn syrup. And to make corn syrup, you first have to make cornstarch.
1. Turn corn into cornstarch
- Steep the corn in hot water for 30-48 hours, which ferments it slightly.
- Separate the germ from the endosperm (mechanically, not chemically) and grind each separately.
- Wash the starch off the ground-up germ and endosperm to form a corn steep liquor.
- Extract the starch from the corn steep liquor via a centrifuge, then dry it out.
At the end of these steps, you have cornstarch. You next need to turn the cornstarch into corn syrup.
2. Turn cornstarch into corn syrup
- Subject the cornstarch to alpha-amylase, which breaks the starch into oligosaccharides (short-chain sugars) such as maltotriose.
- Subject the oligosaccharides to glucoamylase, which breaks them down into monosaccharides.
These steps result in regular, garden-variety corn syrup. Corn syrup consists almost entirely of glucose. To turn this glucose syrup into commercial high-fructose corn syrup, you must then:
3. Turn corn syrup into commercial-grade high-fructose corn syrup
- Subject the corn syrup to xylose isomerase. This converts some of the glucose into fructose. The result is HFCS 42, which is 42% fructose and 58% glucose (not including the portion that's water).
- Put the HFCS 42 through liquid chromatography to isolate the fructose, in much the same way that you isolate U-235 during uranium enrichment. The result is HFCS 90, which is 90% fructose and 10% glucose.
- Finally, add a little of this HFCS 90 back into the HFCS 42, until you raise its fructose concentration to 55% fructose.
The end result is called HFCS 55. This is the high-fructose corn syrup used in American soft drinks.
(The above steps are somewhat simplified, and don't list every compound used in processing. For example, caustic soda and hydrochloric acid are used throughout the milling process to adjust the pH of the product line.)
Do all these steps mean that high-fructose corn syrup is "processed food"? Yes. But:
For comparison, here's how sugarcane is turned into table sugar
- Shred the sugarcane with scary-looking revolving knives.
- Mix the shredded cane with water and crush between rollers.
- Do this over and over until you collect all the cane juice (10-15% sucrose). The left over fibers, called bagasse, can be burned to power the cane mill.
- Mix the cane juice with lime (calcium hydroxide) to raise its pH to 7.
- Let the lime (and other solid impurities) settle out.
- Concentrate the clarified cane juice in an evaporator. The result is evaporated cane juice, which is 60% sucrose.
- Concentrate this syrup under vacuum until it's supersaturated, then seed it with fine sugar crystals. This causes big sugar crystals to form, in much the same way as when you make rock candy.
- Put it in a centrifuge to separate the sugar crystals from the mother liquor. (The mother liquor can be further processed until it becomes molasses, but this is a separate product.)
- Re-melt the sugar crystals and put them back in the evaporator from 3 steps ago, and repeat the process as many times as necessary until it's over 90% sucrose. This is called "raw" sugar.
- Mix the raw sugar with heavy syrup and centrifuge it, to wash away the less-pure outer coating of the sugar crystals.
- Clarify this by adding phosphoric acid and calcium hydroxide. Be sure to skim the resulting calcium phosphate off the surface.
- Filter out any remaining solids from the sugar syrup.
- Decolor it by filtering through a bed of activated carbon or, in more modern plants, ion-exchange resin.
- Concentrate the purified syrup to supersaturation and repeatedly crystallize under vacuum.
- Centrifuge to remove any liquid.
- Dry the sugar in a hot rotary dryer, much like a clothes dryer.
- Blow cool air through it for several days in a "conditioning silo". You now finally have granulated sugar, 100% sucrose.
Chemical difference between HFCS and sucrose
Common table sugar, formally called sucrose, is a disaccharide consisting of a fructose molecule and a glucose molecule bonded together. When ingested, an enzyme in the gut named sucrase breaks this bond, resulting in a 50%-50% mixture of free-floating fructose and glucose molecules. These separated molecules are what are absorbed into the blood stream.
High-fructose corn syrup, by contrast, is a mixture of free-floating fructose and glucose molecules. The form of HFCS used in American soft drinks, called HFCS 55, consists of 55% fructose and 45% glucose. ("High fructose" is a relative term; normal corn syrup consists of over 90% glucose.) When ingested, these separated fructose and glucose molecules are absorbed into the blood stream without modification.
Nutritionally, then, there are only two real differences between table sugar and HFCS:
- The former consists of 50% fructose and 50% glucose, while the latter consists of 55% fructose and 45% glucose. That's a rather tiny 5% difference.
- The glucose and fructose in HFCS are absorbed into the blood stream directly, while the glucose and fructose in table sugar can only be absorbed after it's broken down by sucrase in the small intestine, which could theoretically take a little bit of time and thus (slightly) reduce the "spiking" of the imbiber's blood sugar levels.
Other glucose-fructose mixtures similar to HFCS
- Invert sugar. Used in the baking industry since 1883. It's formed by taking sucrose and subjecting it to heat, invertase enzymes, and/or weak acids until most of the sucrose is separated into its two constituent monosaccharades. Commercially-available invert sugar is a mixture of around 15% sucrose (i.e. that portion of the sucrose that survived the inversion process), 42.5% glucose, and 42.5% fructose. Chemically, this is very similar to high-fructose corn syrup, but for some reason nobody is getting up in arms about invert sugar like they are about HFCS.
- Honey. Most commercially produced honey is around 38% fructose, 31% glucose, 7% maltose, 1% sucrose, with a smattering of higher-order oligosaccharides; the remaining percentage is made up mostly of water with a little bit of miscellany thrown in. This is similar enough to HFCS that some beekeepers actually feed HFCS to their bees during the lean times. (This has caused some problems. At high temperatures, HFCS breaks down into hydroxymethylfurfural, which isn't toxic to humans but is deadly to bees; and a commonly-used pesticide on corn crops, imidacloprid, has been implicated in bee deaths.)
- Agave nectar, sometimes touted as a vegan alternative to honey. It also consists primarily of fructose and glucose. Depending on the manufacturer, the ratio can vary from 56% fructose and 20% glucose (the rest presumably being water) to as high as 92% fructose and 8% glucose. This can make it higher in fructose than either honey or HFCS.
- Many fruit juices. The sugars in apple juice, for example, consist of 60% fructose, 27% glucose, and 13% sucrose.
Return to sugar
From a taste perspective, though, the human tongue can distinguish between sucrose and a fructose-glucose mixture. To some, HFCS tastes like sweetened poop. Try a Coca-Cola from or while visiting somewhere besides the United States and see what you think.
In the last several years, Pepsi has released "Throwback" versions of Pepsi, Mountain Dew and Dr. Pepper, sweetened with sucrose and (sometimes) featuring previous-generation labels on cans and bottles. Their labels proudly announce, "Made with real sugar!". While originally only run for a few months at a time, support and demand has been so popular that, in many consumer market areas, the Throwback versions remain as regular items in grocery stores, sold alongside their HFCS counterparts.
Other eclectic or "gourmet" soft drinks, such as Sioux City Sarsaparilla, have always and continue to use sugar instead of HFCS, so as to not compromise on flavor.
Coca-Cola has yet to catch onto the idea with its flagship products, but anyone living in a major city with a substantial Hispanic population should know they can go to any carniceria and grab a glass bottle of Coca-Cola from Mexico, complete with sugar, for about the same price or a little more than a regular plastic bottle of Coke from Georgia. The nice woman behind the counter will have a bottle opener for you (that is, if you don't already have one at the ready). In some American cities, even mainstream grocery stores carry the bottles in their ethnic food aisles.
Both major drink brands tend to release sucrose-sweetened versions of all their products for a specific part of the year, namely during the lead-up to Passover, as HFCS apparently isn't kosher. So those who especially despise HFCS-sweetened sodas should keep an eagle eye out in the soft-drink aisle of their grocery stores during Spring for soda bottles featuring yellow caps. Interestingly, this is also why fast-food restaurants in places with a large Roman Catholic population tend to advertise "limited time offer" promotions of products such as fish sticks and the like during the same part of the year: Fish is exempt from the Catholic ban on consumption of meat during Lent.
Health concerns and responses
A number of companies, as part of their public relations campaigns, have removed high-fructose corn syrup from their products. The common perception is that high-fructose corn syrup is more harmful than table sugar. The American Medical Association, while calling for more research on the subject, concluded that "it appears unlikely that HFCS contributes more to obesity or other conditions than sucrose," and stated that "the adverse health effects of HFCS, beyond those of other caloric sweeteners, most of which contain fructose, are not well established. Consumption of added caloric sweeteners in general has increased over the last 30 years, as has total calories. Likewise, rates of obesity have risen even in countries where little HFCS is consumed."
This has not prevented the odd rat study here and there from showing health differences between HFCS and sugar.
The U.S. Food and Drug Administration categorizes HFCS 42 and HFCS 55 as "generally recognized as safe" (GRAS). This is due to their chemical similarity to sugar and honey. Until about 2014, however, they didn't categorize HFCS 90 as GRAS, on the basis that there's no common foodstuff that a 90% fructose/10% glucose mixture resembles. This was a little odd, considering that both agave nectar (which can be over 90% fructose) and pure fructose have both been sold as food in the United States. Now, however, HFCS 90 can be used in foods sold in the U.S., which has upset some alarmists. Since it's 90% fructose, HFCS-90 can be listed on a food label as simply "fructose" instead of HFCS.
Legitimate concern exists over the following:
Some HFCS plants may be using a process that adds trace amounts of mercury. However, the concentrations that make it into processed foods are in the parts per trillion range, which is more dilute than even the standards for safe drinking water can detect. The mercury comes from caustic soda used in turning some of the corn syrup into fructose; some of the chlor-alkali plants that produce caustic soda use mercury in their production process. However, "mercury-cell" technology is now considered outdated, and newer chlor-alkali production plants don't use it; all but two American chlor-alkali plants have phased out mercury-cell technology. It is still in use in many non-U.S. chlor-alkali plants, though, and there are no requirements for an HFCS manufacturer to disclose where they buy their caustic soda from.
Prevalence in American processed food
Due to how much cheaper it is than cane/beet sugar in the United States, it can be added to foods in much higher quantities. This may be a more likely reason for the rise in obesity, type 2 diabetes, and non-alcoholic fatty liver disease since its introduction as a food additive than anything inherently wrong with HFCS itself.
The U.S. is one of the few countries on Earth where HFCS is cheaper than sucrose. In Canada and Mexico, which border the United States, sucrose is cheaper than HFCS, and so most soft drinks there are still sweetened with cane/beet sugar. This economic state of affairs arises because of:
- U.S. import tariffs on sucrose manufactured in other countries, and
- subsidies for U.S. corn farmers.
The fact that the usual 55/45 formulation of HFCS contains slightly more fructose than glucose does make a difference for people with a digestive disorder called fructose malabsorption. As much as 30% of the adult population may suffer from fructose malabsorption. To them, food sweetened with sucrose (which by definition contains equal amounts of fructose and glucose) will generally be digested without difficulty, but food sweetened with HFCS can cause bowel or gut problems. Glucose enhances absorption of fructose, so fructose from foods with fructose-to-glucose ratio <1, like white potatoes, are readily absorbed, whereas foods with fructose-to-glucose ratio >1, like apples and pears, are often problematic regardless of the total amount of fructose in the food.
Since HFCS ultimately comes from corn, a possibility exists that extremely small trace amounts of corn protein may survive processing and make it into the final product. Corn allergies are among the top 10 food allergies in the United States, and sporadically-reported cases do exist of folks with corn allergies having allergic reactions to products containing high-fructose corn syrup.
No large-scale definitive study has been done of this phenomenon, which could eliminate the possibility of other corn-related trace ingredients causing the allegic reaction, so ultimately the jury is still out. However, according to one representative of the American Academy of Allergy Asthma & Immunology, "Corn syrup (also known as glucose syrup), corn syrup solids, glucose, dextrose, maltodextrin, corn oil, and high fructose corn syrup ... have no detectable corn protein residues and should be quite safe for someone with IgE-mediated allergy to corn."
Aside from simply higher quantities found in food, HFCS is very difficult to avoid in the supermarket; products from bread, to pasta sauce, to chicken nuggets contain HFCS. It is very easy to eat large quantities of the ingredient without even knowing it, such as by eating restaurant food that does not mark HFCS in its preparation or by simply not reading labels. Struggling families often find it more economical in the United States to eat poorly. Children consume more added sugar from food than from beverages, and many products targeted at children are overflowing with HFCS and other sugars to make them more palatable to young tastes.
Although there are many peer-reviewed studies on the safety and properties of HFCS (to the point of the Corn Refiners Association creating a whole section of their HFCS Public Relations website for them!), questions have been raised about the full truthfulness of the PR effort, including by the FDA in response to the Corn Refiners' attempts to rename HFCS "corn sugar", a label already attributed to dextrose. (Not that corn doesn't have its detractors too; the fact that most corn is genetically modified food, and is grown by large agribusiness firms like ConAgra, has created a whole "corn free" movement in the U.S..)
As of July 2008, the FDA is of the opinion that HFCS counts as "natural" if no synthetic fixing agents come into contact with it during manufacturing.
A rational conclusion
The amount of health hysteria surrounding HFCS has actually harmed awareness of its presence in food. Being wary of it, such a ubiquitous part of the American food supply, is sometimes slammed as a symptom of being a health food nut (many 'health foods' contain it too) or a crazy moonbat, when there's really some normal, obvious conclusions at hand:
- A thinking human being should probably be aware of what exactly goes into their body.
- Too much sugar is bad for people.
- People should probably eat less of it.
- Unfortunately, junk food is still delicious.
In a nutshell
- High Fructose Corn Syrup: Tasty Toxin or Slandered Sweetener?, on Science-Based Medicine, 23-Aug-2010
- Is the increased use of high-fructose corn syrup responsible for the rise in obesity?, from The Straight Dope, 10-Sept-2004
- 5 Reasons High Fructose Corn Syrup Will Kill You, an article by a "Functional Medicine" practitioner that hits just about every hyped scare point.
- High fructose corn syrup–it’s just sugar, from Skeptical Raptor's blog, 30-June-2014 (revised 5-May-2015)
- High fructose corn syrup — debunking the myths with science and facts, from Skeptical Raptor's blog, 20-Jan-2022
- Dark Sugar: The decline and fall of high-fructose corn syrup, from Slate, 28-April-2009
- High Fructose Corn Syrup by C0nc0rdance, a 15 minute comprehensive essay on the stuff.
- "High-fructose corn syrup" on Wikipedia
- Actually, it's 24% water, 42% fructose, and 34% glucose; but if you discount the water portion, the remainder is 55% fructose and 45% glucose.
- In the case of sugar-sweetened soft drinks, however, a study in the July 2007 American Journal of Clinical Nutrition (86(1):116-123) discovered that half of the sucrose breaks down into fructose and glucose within 30 days of bottling, due to the acidity of the soda pop. This is the same basic process that produces invert sugar.
- Valdmanis, Richard. "Honeybee food may contribute to U.S. colony collapse - study", Reuters, published 3 June 2013, accessed 15 June 2013. (Reprinted by Huffington Post here.)
- Yeah, that's a good one!
- Sugar Is Back on Food Labels, This Time as a Selling Point, New York Times
- The bitter truth about fructose alarmism, Alan's Blog, 29-Jan-2010
- The Health Effects of High Fructose Syrup, Report 3 of The Council on Science and Public Health (A-08)
- Ruff et al., Compared to Sucrose, Previous Consumption of Fructose and Glucose Monosaccharides Reduces Survival and Fitness of Female Mice, The Journal of Nutrition, March 2015, pp. 434-441
- Watch Out: Corporations Have Renamed ‘High Fructose Corn Syrup’, Natural Society, 10-Dec-2014
- Corn Refiner's Association, Sweeteners: 'A third product, HFCS-90, is sometimes used in natural and “light” foods, where very little is needed to provide sweetness. Syrups with 90% fructose will not state high fructose corn syrup on the label, they will state “fructose” or “fructose syrup.”'
- Mercury from chlor-alkali plants: measured concentrations in food product sugar
- A Plea for Equal-Opportunity Cynicism, The Wandering Scientist
- Olin prepares for mercury free future after 47 years, Augusta, Georgia, July 2012
- Not Enough Evidence to Indict High Fructose Corn Syrup in Obesity, University of Maryland, 2007. Full text of study here
- Although most cases of corn "allergies" may be nothing more than corn sensitivity, according to this article
- Avoidance of corn allergen, aaaai.org, Response from Steven Taylor, PhD.
- Consumption of Added Sugar Among U.S. Children and Adolescents, 2005–2008
- 'Corn Sugar' false advertising, FDA warns
- HFCS is natural, says FDA in a letter