This post was prepared with the help Carol Harvey, Director of food/nutrition labeling and product development at Palate Works.
High Fructose Corn Syrup is found in many foods and beverages in the US. Surplus corn supply and the need for low-cost sweeteners for the food industry gave rise to an ingredient that has found itself in the crossfire of nutritionists, the Sugar Association, and various consumer groups.
In a previous post, we explained why HFCS is such a beloved ingredient of the food industry. Today we will explain how it is manufactured.
You can’t make high fructose corn syrup at home. That’s where “corn refiners” come in. These are companies that have manufacturing facilities where corn is converted into various ingredients to be used by the food industry (and other industries too).
Why is corn chosen to begin with?
Corn has a very high starch content, about 80% of the kernel. Other high starch crops could potentially be used (and rice actually is, but in much smaller quantities). To make high fructose corn syrup, you need to first make (regular) corn syrup, which is simply breaking down the starch into glucose.
Corn starch is broken down into individual glucose molecules using various enzymes and acids. A pearl necklace analogy can help explain: Corn starch is like a long pearl necklace. Each individual pearl is a glucose molecule. The glucose molecules are strung together by chemical bonds that create the “pearl necklace”, or in technical terms, a glucose polymer.
The enzymes and acids are the “scissors” that cut the necklace into smaller pieces, some as small as just one pearl (glucose). Pure glucose is only 62% as sweet as table sugar. Corn syrup consists of pure glucose but can also include longer chain sugars that are even less sweet. The corn syrup used for HFCS production is almost 100% glucose molecules. Since it’s not as sweet as sugar, another molecule is required…
That’s where fructose comes in. Fructose, like glucose, is a monosaccharide (a single molecule sugar). But fructose is much sweeter than glucose.
Table sugar is made from glucose and fructose. (It is a disaccharide, made of 2 monosaccharides that are chemically bound to each other: glucose + fructose).
High Fructose Corn Syrup is also made of glucose and fructose, but they are not chemically bound to each other. (In Canada and Europe, HFCS is therefore called glucose / fructose syrup.)
HFCS’s proportion of fructose to glucose is not 50/50 as in table sugar, but fairly close. HFCS comes in two variants: HFCS55 and HFCS42. HFCS55 has 55% fructose and is 99% as sweet as sugar. HFCS42 is only 92% as sweet as sugar because it has a higher proportion of the less sweet glucose. Both varieties are about one quarter water by weight.
Although fructose is found naturally in fruit and in honey, these are not the source of fructose that is added to glucose in producing HFCS. It’s actually more chemistry: Fructose is a structural isomer of glucose – they are both molecules with the same number of atoms for carbon, oxygen, and hydrogen, but they are arranged a bit differently. Using a specific enzyme called Xylose Isomerase, the glucose in corn syrup is converted into fructose. The conversion is stopped when the correct proportion is reached – HFCS42 or HFCS55.
Some math fun:
A bushel of corn (70 lbs) can be converted to about 32 lbs. of high fructose corn syrup. How may cans of soda pop could be sweetened with that?
Answer: 372 cans! A singe 12 ounce can of pop has 39 grams of Sugars, all from HFCS. 32 lbs is 14.5 Kg or 14,500 grams. Dividing 14,500 by 39 grams we get 372 cans.
1. The Corn Refiners Association
2. John S. White, Ph.D., President, White Technical Research
3. FDA, USDA website