High fructose corn syrup comes from corn. Specifically, it’s made by extracting starch from corn kernels and then using enzymes to convert that starch first into glucose and then partially into fructose. The result is a liquid sweetener that was introduced to the food and beverage industry in the 1970s and quickly became one of the most common sweeteners in processed foods across the United States.
From Corn Kernel to Starch
The process begins at a wet milling facility, where corn kernels are broken down into their individual components. A large-scale plant can process around 2.5 million kilograms of corn per day. The kernels go through a series of separation steps: grain cleaning, steeping (soaking in water to soften the kernels), and then mechanical separation of the germ, fiber, gluten, and starch. Each part has commercial value. The germ gets pressed or treated with solvents to extract corn oil. The fiber and protein fractions become animal feed ingredients like corn gluten feed and corn gluten meal. The starch, a white powdery substance, is the raw material for high fructose corn syrup.
Turning Starch Into Sugar
Corn starch is a long chain of glucose molecules bonded together. To turn it into a sweetener, manufacturers need to break those chains apart. This happens in two enzymatic steps.
First, an enzyme called alpha-amylase chops the long starch molecules into shorter fragments. These fragments are a mix of small chains containing two, three, or more glucose units, but very little free glucose on its own. A second enzyme, glucoamylase, then clips those short chains into individual glucose molecules. At this point, the product is essentially corn syrup: a thick, clear liquid made almost entirely of glucose.
But glucose is only about 70% as sweet as table sugar. To boost the sweetness, manufacturers add a third enzyme, glucose isomerase, which rearranges some of the glucose molecules into fructose. Fructose is considerably sweeter than glucose, so converting a portion of the glucose to fructose brings the overall sweetness closer to that of regular sugar. The enzyme works by shifting a hydrogen atom within the glucose molecule, flipping it into fructose without adding or removing anything.
Two Main Varieties
The enzymatic conversion doesn’t turn all the glucose into fructose. Instead, it produces a syrup that’s about 42% fructose, known in the industry as HFCS-42. The remaining sugars are primarily glucose, with a small percentage of short-chain glucose fragments like maltose.
For soft drinks and other beverages, manufacturers want something sweeter. They use a chromatographic separation process to concentrate the fructose fraction, creating HFCS-55, which contains about 55% fructose and roughly 40% glucose. Testing of commercial carbonated beverages has confirmed these ratios closely, with fructose averaging 55.6% of total sugars.
HFCS-42 is the more common form in solid foods like breads, cereals, yogurts, and condiments. HFCS-55 dominates in sodas and other acidic beverages, where its liquid form and monosaccharide composition offer stability advantages over granulated sugar.
How It Compares to Table Sugar
Table sugar (sucrose) is also made of glucose and fructose, but with one key structural difference. In sucrose, each glucose molecule is chemically bonded to a fructose molecule, forming a single two-part unit. Your digestive system has to break that bond before absorbing the individual sugars. In high fructose corn syrup, the glucose and fructose are already separate, floating freely in solution. This is why HFCS is sometimes described as a mixture of “free” glucose and fructose.
In terms of overall sugar ratios, HFCS-55 and sucrose are remarkably similar. Sucrose is a perfect 50/50 split of glucose and fructose. HFCS-55 is roughly 55/40. HFCS-42 tilts the other direction, with more glucose than fructose. The practical difference in composition is modest, which is one reason HFCS was able to replace sugar so seamlessly in thousands of products.
Why Corn Instead of Cane
The rise of HFCS in American food wasn’t just a matter of chemistry. It was driven by economics and government policy. For over 80 years, federal laws have limited sugar imports into the United States, keeping domestic sugar prices artificially high. In 2013, these price supports effectively cost American consumers an estimated $1.4 billion per year.
At the same time, corn has been one of the most heavily subsidized crops in the country, grown in massive midwestern monoculture fields with the benefit of advanced agricultural technology. The combination of expensive sugar and cheap corn created ideal conditions for a corn-based alternative. During the 2000s, the average wholesale price of beet sugar was about 27.3 cents per pound, while HFCS averaged 21.7 cents per pound. Even as that gap narrowed over the years, HFCS remained the cheaper option.
HFCS use grew rapidly from the mid-1970s through the mid-1990s, particularly in beverages. Its liquid form made it easier to handle in production compared to granulated sugar, and it mixed readily into drinks, sauces, and other processed foods. Today it appears in products ranging from ketchup and salad dressings to ice cream and fast food.
Regulatory Status
The FDA classifies high fructose corn syrup as “Generally Recognized as Safe” (GRAS) and permits its use in food with no specific quantity limits beyond standard good manufacturing practice. The federal code formally defines it as a sweet, nutritive saccharide mixture containing either approximately 42% or 55% fructose, prepared from corn starch by partial enzymatic conversion of glucose to fructose. The higher-fructose version (HFCS-55) is made by concentrating the fructose portion of the 42% product, not by a different enzymatic process.