You’ll be the first to admit, won’t you, that corn contains a lot of starch? Well, starch is the key to corn syrup. They convert cornstarch into sugar by the magic of chemistry.
Take away the water from a kernel of corn and the remainder is about 82 percent carbohydrates, a classification of natural organic compounds that includes sugars, starches, and cellulose. The cellulose, a tough material that makes up the cell walls of most plants, is in the corn kernel’s skin. The sugars, as you already know, aren’t very abundant. That leaves starches as the major constituent of corn kernels.
Bushel for bushel, the United States produces roughly five thousand times as much corn as sugar cane. And much of the sugar that we import comes from tropical countries that have never won awards for political stability or friendliness to the United States. So if American food producers could just make sugar out of cornstarch, they would be in great shape. Well, they can.
Sugars and starches are very close chemical cousins. In fact, starch molecules consist of hundreds or thousands of glucose molecules, all stuck together, and glucose is a fundamental sugar.
So, in principle, if you could break corn’s starch molecules down into smaller pieces, you would get a lot of loose molecules of glucose. You will also produce some molecules of maltose, another sugar whose molecules consist of two glucose molecules, still stuck together. And you would get a number of even larger fragments consisting of dozens of glucose units stuck together. Because these larger molecules can’t flow past one another as easily as small molecules, the mixture you would wind up with would be thick and syrupy.
It turns out that almost any acid, as well as a variety of enzymes from plants and animals, can perform this trick of breaking starch molecules down into a syrup of sugars. Enzymes in saliva do it all the time. (An enzyme is a natural substance that helps a specific chemical reaction to take place. Many important life processes wouldn’t work without enzymes.)
Chew a starchy saltine cracker for several minutes and it will start tasting sweet.
Glucose and maltose, however, are only about 70 percent and 30 percent as sweet, respectively, as sucrose, that wonderfully sweet sugar in sugarcane that we are in the habit of referring to as just plain sugar. So if you break down cornstarch the way we’ve described, it might average only about 60 percent of the sweetness of “real sugar.” Food processors get around this by using yet another enzyme to convert some of the glucose into fructose, a sugar that’s even sweeter than sucrose. That’s why you’ll see “high fructose corn syrup” listed on some labels.
But there’s another problem. Glucose-maltose-fructose corn syrup may be a great economic boon to the American food industry, but it just doesn’t taste quite the same or carry other flavors as well as good old sucrose.
Fruit preserves and soft drinks, for example, just aren’t what they used to be before the food processors abandoned cane sugar for the cheaper and more readily available corn sweeteners. As a label-reading consumer, the best you can do is to choose those products that are sweetened with the highest proportion of sucrose, which is listed simply as “sugar” on the labels.
By the way, if you can ever find a bottle of pre-1980 Coca-Cola, you will see what I mean. That’s the year that Coke reportedly switched from sugar to corn sweeteners in its U.S. bottling plants. It is undoubtedly still made with sugar in countries where sugar cane is cheap. Next time you’re south of the border, bring some back. But don’t use the word Coke within earshot of a customs agent.