What is the difference between sugar, other natural sweeteners and artificial sweeteners? Food chemist explains sweet science

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(THE CONVERSATION) A quick stroll down the beverage aisle of any local store reveals the incredible ingenuity of food scientists in search of sweet flavors. In some drinks you will find sugar. Diet soda can contain an artificial or natural low-calorie sweetener. And in almost everything else is high fructose corn syrup, the king of American sweetness.

I am a chemist who studies compounds found in nature, and I am also a food lover. With confusing food labels claiming that foods and drinks are healthy, sugar-free, or “free of artificial sweeteners,” it can be confusing to know exactly what you’re consuming.

So what are these sweet molecules? How can cane sugar and artificial sweeteners produce such similar flavors? First, it helps to understand how taste buds work.


The taste buds and chemistry

The “taste card” – the idea that you taste different flavors on different parts of your tongue – is far from the truth. People can taste all flavors wherever there are taste buds. So what is a taste bud?

Taste buds are areas of your tongue that contain dozens of taste receptor cells. These cells can detect all five flavors – sweet, sour, salty, bitter, and umami. When you eat, food molecules are dissolved in saliva and then washed through the taste buds, where they bind to the various taste receptor cells. Only molecules with certain shapes can bind to certain receptors, which produces the perception of different flavors.

Molecules that taste sweet bind to specific proteins on taste receptor cells called G proteins. When a molecule binds to these G proteins, it triggers a series of signals that are sent to the brain where it is interpreted as sweet.

Natural sugars

Natural sugars are types of carbohydrates called saccharides made up of carbon, oxygen, and hydrogen. You can imagine sugars as rings of carbon atoms with oxygen and hydrogen pairs attached to the outside of the rings. The oxygen and hydrogen groups are what make sugar sticky to the touch. They behave like velcro, adhering to oxygen and hydrogen pairs on other sugar molecules.

The simplest sugars are monomolecular sugars called monosaccharides. You’ve probably heard of it. Glucose is the most basic sugar and is mainly made by plants. Fructose is a fruit sugar. Galactose is a milk sugar.

Table sugar – or sucrose, which comes from cane sugar – is an example of a dissaccharide, a compound made up of two monosaccharides. Sucrose is formed when a glucose molecule and a fructose molecule come together. Other common dissacharides are lactose from milk and maltose, which comes from grains.

When these sugars are consumed, the body processes them slightly differently. But ultimately, they’re broken down into molecules that your body converts into energy. The amount of energy from sugar – and all foods – is measured in calories.

High fructose corn syrup

High fructose corn syrup is a staple of American foods, and this hybrid sugar sweetener needs a category of its own. High fructose corn syrup is made from corn starch, the main carbohydrate found in corn. Corn starch is made up of thousands of linked glucose molecules. On an industrial scale, starch is broken down into individual glucose molecules with the help of enzymes. This glucose is then treated with a second enzyme to convert part of it into fructose. Typically, high fructose corn syrup contains about 42% to 55% fructose.

This blend is mild and inexpensive to produce but has a high calorie content. As with other natural sugars, too much high fructose corn syrup is bad for you. And since most processed foods and drinks are loaded with it, it’s easy to overeat.

Natural sweeteners without sugar

The second category of sweeteners could be defined as natural sweeteners without sugar. These are food additives such as stevia and monk fruit, as well as natural sugar alcohols. These molecules are not sugars, but they can still bind to sweet receptors and therefore taste sweet.

Stevia is a molecule derived from the leaves of the Stevia redaudiana plant. It contains “soft” molecules that are much larger than most sugars and to which three glucose molecules are attached. These molecules are 30 to 150 times sweeter than glucose itself. The sweet molecules in monk fruit are similar to stevia and 250 times sweeter than glucose.

The human body has great difficulty in breaking down both stevia and monk fruit. So even though they are both very sweet, you don’t get any calories from eating them.

Sugar alcohols, like sorbital, for example, are not as sweet as sucrose. They can be found in a variety of foods, including pineapples, mushrooms, carrots, and seaweed, and are often added to diet drinks, sugar-free chewing gum, and many other foods and drinks. Sugar alcohols are made up of chains of carbon atoms instead of circles like normal sugars. Although they are made up of the same atoms as sugars, sugar alcohols are not well absorbed by the body, so they are considered low calorie sweeteners.

Artificial sweeteners

The third way to make something sweet is to add artificial sweeteners. These chemicals are produced in laboratories and factories and are not found in nature. Like all things that taste sweet, they do so because they can bind to certain receptors in the taste buds.

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So far, the United States Food and Drug Administration has approved six artificial sweeteners. The best known are probably saccharin, aspartame, and sucralose – better known as Splenda. Artificial sweeteners all have different chemical formulas. Some look like natural sugars while others are drastically different. They’re usually several times sweeter than sugar – saccharin is an incredible 200 to 700 times sweeter than table sugar – and some of them are difficult for the body to break down.

While a sweet dessert can be simple treat for many, the chemistry of how your taste buds perceive sweetness isn’t that simple. Only molecules with the perfect combination of atoms taste sweet, but bodies process each of these molecules differently when it comes to calories.

This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/whats-the-difference-between-sugar-other-natural-sweeteners-and-artificial-sweeteners-a-food-chemist-explains-sweet-science-172571.

Rachel J. Bradford