Embedded Files
Engage:
Engage:
Carbs, carbs, carbs. Are they good for you? Should they be avoided? What is the story? You may already know more than you think.
Get started by taking the 4-question quiz.
Carbohydrates
Carbohydrates
Subunit: Simple sugars, like glucose
Function: Provide quick energy
Foods: Sugars, pasta, bread, rice, potatoes, fruits, vegetables
Caloric density: 4 calories per gram
Explain: Background Information
Explain: Background Information
Glucose is the main building block for all carbohydrates, yet you rarely see glucose listed on a nutritional label. That is because this simple sugar gets arranged into starches, fibers, and other sugars, which are listed on the label.
Where does this glucose come from? Plants produce glucose (and oxygen) through photosynthesis.
This planet has an amazing cycle going on! Plants produce glucose and oxygen for animals, and animals produce carbon dioxide and water for plants.
As the plant grows, it is storing glucose as starch in the potato (dotted lines between glucose molecules), and as fiber in the leaf structure (solid lines).
Carbohydrates in our foods can be broken up into three main groups.
Carbohydrates in our foods can be broken up into three main groups.
Sugars
Sugars are easily and quickly digested because they do not need to break down much, if at all, before entering the bloodstream.
Starches
Starches are have bonds between glucose molecules that humans can break easily with digestive enzymes. Starches are polysaccharides.
Fibers
Fibers have bonds between glucose molecules that humans cannot break easily with digestive enzymes. Fibers are polysaccharides.
Culinary Carbohydrates
Culinary Carbohydrates
How do these different carbohydrates effect foods and cooking?
Sugars do many of our favorite things: sweeten, caramelize, crystalize, and preserve foods. Not all sugars have the same level of sweetness. Fructose is the sweetest sugar which is one reason why high fructose corn syrup was produced to sweeten foods. Lactose, the sugar in milk, is not very sweet. Sugars get easily absorbed into the bloodstream, causing blood glucose levels to go up quickly.
Starches are made of hundreds to thousands of linked glucose molecules. These complex chains (polymers) provide structure in many foods such as baked goods, and help to bind ingredients together. Because starch changes shape when heated and cooled, it can be used to thicken sauces and make gelatins. Wheat flour is a common starch in the American diet.
Fibers are also made of thousands of linked glucose molecules. They provide structure and bulk to foods. They do not get digested easily, if at all, so they provide roughage in the diet. Why is this important? Read below.
Cellulose is the most abundant carbohydrate on the planet. We cannot digest it, but it provides roughage in our diets. Cows and other ruminants can digest cellulose which is why they can eat grass and we can't.
Fabulous Fiber
Fabulous Fiber
Why do we care about a component of our food that does not provide us calories or nutrients? Oh-so-many reasons:
Fiber adds bulk to our foods, which can make us feel full and satisfied after a meal.
Fiber slows digestion (see figure below). Starches and sugars can get caught up in the fiber and are released slowly over time.
Because most fibers are not broken down to their glucose building blocks, the glucose does not enter our bloodstreams during digestion. No digestion means no calories from this food. It is the ultimate low caloric-density food.
Fiber provides a comfy home for microbes in our guts. This microbiome plays an important part in health. Learn more here.
Fiber mostly comes from fruits and vegetables which provide us with other needed vitamins and nutrients.
Fiber helps move food through the digestive tract. In other words, it helps us poop regularly and with a first-rate form. (Is there really a notably good form? Yes. Check out the Bristol Stool scale if you feel up to it.)
This figure shows a person’s hypothetical digestive tract after eating two kinds of diets.
A represents a high fiber meal that includes foods like beans, peas, nuts, and broccoli. These digest slowly and release glucose into the blood over time.
B represents a low fiber meal that includes foods like white bread, white rice, white pasta, and especially sugar drinks like soda. These release glucose more quickly and can cause blood glucose to spike after eating.
Elaborate: Labs and Lessons
Elaborate: Labs and Lessons
This interactive game allows students to make choices, collect data, and compare their scores with other players.
How can players keep their blood sugar (glucose) within a healthy range throughout the day?
What food choices and exercise decisions can players make to balance glucose levels?
How does type 2 diabetes status and environment make this easier or harder?
Where can glucose be found in food?
How does yeast contribute to making bread?
Evaluate:
Evaluate:
Choose one or more assessment options from the Student Choice Grid for this macromolecule.
Page updated
Report abuse