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Engage:
Engage:
We hear a lot of things about fat in our food.
What do you already know about fat in the diet?
Take the 5-question quiz.
Fats
Fats
Subunit: Triglyceride (Glycerol + 3 Fatty Acids)
Function: Store energy, cushion organs, insulate
Foods: Fats, oils, butter, nuts
Caloric density: 9 calories per gram
Explain: Background Information
Explain: Background Information
Culinary Fats
Aside from the nutrients they provide, fats are very important in cooking. Fats give food flavor and texture. Fats provide an important sensory experience that is hard to recreate. And the type of fats we use when cooking can impact our health. Fats are categorized based on the types of bonds they make, so let's learn more about the molecular nature of this tasty and important macromolecule.
What are fats and where are they found?
What are fats and where are they found?
The most common type of fats in the diet are triglycerides. These are made up of one glycerol backbone attached to three fatty acids tails (tri = three).
Each tail is made of chains of carbon (C) and hydrogen (H) atoms. The chemical bond structure between theses atoms determines the type of fat.
The long tails of carbon (C) and hydrogen (H) give dietary fats some common properties. They don’t evaporate quickly, and they don’t mix with water. Fats and oils are insoluble in water because their long tails of carbon (C) and hydrogen (H) are nonpolar, meaning they have no charge. Water is a polar molecule, which means it has small charged regions. Polar molecules mix with polar molecules, but don’t intermix with nonpolar molecules. In other words, “like dissolves like.”
If you have ever made salad dressing with oil (fat-based) and vinegar (water-based), you have seen them separate.
Culinary Fats
Culinary Fats
This peanut butter nutritional label shows the amounts of saturated fats, trans fats, polyunsaturated fats, and monounsaturated fats. What's the difference? Why do we care?
Fats in our diets are mostly triglycerides. The tails are made of long chains of carbon (C) and hydrogen (H). The chemical bond structure between these atoms determines the type of fat. Energy is stored in the bonds. When the long tails are broken down, energy is released. Let's take a closer look.
Types of Fats
Types of Fats
Saturated fats
•No double bonds in tails
•Mostly fats from animals
•Solid at room temperature
•Examples: butter, lard, cheese, cream, whole milk
•Avoid or limit foods with high amounts of these
Monounsaturated fats
•One double bond in tail
•Mostly fats from plants
•Liquid at room temperature
•Examples: olive oil, avocado, peanuts
•Healthy fat choice
Polyunsaturated fats
•Many double bonds in tails
•From plants and animals
•Liquid at room temp
•Source of Omega fats
•Examples: fish, sunflower oil, some nuts and seeds
•Healthy fat choice
Trans fats
•Double bonds in alternate configuration
•Artificially made
•Examples: processed baked goods, deep-fried fast foods, stick margarine
•Avoid these
Based on the composition, which of the above fats are healthiest? Least healthy?
What are trans fats?
What are trans fats?
Most trans fats in our diets are artificially created through an industrial process that makes “partially hydrogenated oils.” These oils are used by restaurants and fast-food outlets to deep-fry food because it can be used many times in commercial fryers. They are also used in many processed foods to extend shelf life. Since 2006, food labels have been required to show the amount of trans fats. These fats should be avoided.
But fat is bad for you, right?
But fat is bad for you, right?
We need fats in our diets to store energy, insulate organs, absorb some vitamins, and support cell function. However, some fats are healthier than others. It is better to increase unsaturated fats from plants, and those high in Omega oils, and to limit trans fats and saturated fats from animals. Too much saturated fat can cause cholesterol to build up in your blood vessels.
Even with healthy fats, they should be limited to about 25% of the calories in the diet. Since fat packs 9 calories per gram (compared to 4 calories per gram for both carbohydrates and protein), a little bit of fat goes a long way.
Fake Fats
Fake Fats
Artificial sugars have been around for a long time, and food scientists have been working for years to create artificial fats. Here’s the story:
Olestra. What if I told you that food scientists had created a fat substitute that has the same taste, mouth-feel, and texture as natural fat, yet contains no calories? Meet Olestra.
Instead of a glycerol backbone found in triglycerides, Olestra uses a sucrose (sugar) backbone which allows six to eight fatty acids to attach instead of the usual three. Digestive enzymes cannot break down olestra, so it doesn’t get absorbed into the bloodstream. It travels through the intestines without contributing any calories to the diet.
Approved by the FDA in 1996, Olestra was used in potato chips, tortilla chips, crackers, and other fried foods.
After hitting the market, consumer reports of abdominal cramping and bouts of diarrhea skyrocketed, and by 2002 Olestra had received more consumer complaints than any other food additive in history. Many products were discontinued.
In 2003, the FDA removed the warning requirements for labeling from the small number of foods that still contain Olestra. Olestra is banned in Canada and the European Union.
Elaborate: Labs and Lessons
Elaborate: Labs and Lessons
What are the differences in taste, texture, cost, and health impact between types of ground beef?
What can we tell from reading a ground beef label?
Can fat be successfully substituted with a healthier ingredient?
What are some trade-offs when substituting ingredients?
How does oil contribute to caloric density?
What is caloric density and nutrient density, and what is the difference?
How can we choose nutrient dense foods?
Evaluate:
Evaluate:
Choose one or more assessment options from the Student Choice Grid for this macromolecule.
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