1. Chapter 4
Lipids: Fats and Oils

2. Learning Objectives
Describe lipids and list their functions in foods and in the body
Describe the relationship between triglycerides and fatty acids
Define saturated, monounsaturated, and polyunsaturated fats and list foods in which each one is found
Describe trans fatty acids and give examples of foods in which they are found
Identify the two essential fatty acids, list their functions in the body, and give examples of foods in which they are found
Define cholesterol and lecithin, list their functions in the body, identify where they are found in the body, and give examples of foods in which they are found

3. Learning Objectives (cont’d)
Describe how fats are digested, absorbed, and metabolized
Discuss the relationship between lipids and health conditions such as heart disease and cancer
State recommendations for dietary intake of fat, saturated fat, trans fat, monounsaturated fat, polyunsaturated fat, and cholesterol
Distinguish between the percentage of fat by weight and the percentage of kcalories from fat
Calculate the percentage of kcalories from fat for a food item
Discuss the nutrition and uses of milk, dairy products, and eggs on the menu

4. Lipids
Fats
Oils
Cholesterol
Lecithin

5. Functions of Lipids Insulation Cushion around critical organs
Provides energy (adipose cells = compact energy storage)
Protein-sparing
Part of all cell membranes
Transport of fat-soluble vitamins
Essential fatty acids

6. In food, fat enhances: Taste Flavor Aroma Crispness Juiciness
Tenderness
Smooth texture
Creamy feeling
Feeling full

7. A Triglyceride

8. Types of Fatty Acids
Point of
Unsaturation

9. Lecithin A phospholipid Vital component of cell membranes
Acts as an emulsifier

10. All fats in foods contain a mixture of saturated and unsaturated fats.
Triglycerides in Food
Which groups contain the most triglycerides?
Fruits and vegetables
Breads, cereals, rice, pasta, and grains
Dry beans and peas, nuts and seeds
Meat, poultry, fish
Dairy foods
Fats, oils, and condiments
All fats in foods contain a mixture of saturated and unsaturated fats.

11. 3 Types of Triglycerides
1. Saturated triglycerides (saturated fat)
ANIMAL FOODS
Cheese
Beef
Whole milk
Fats in baked goods
Butter
Coconut, palm kernel, and palm oils

12. 3 Types of Triglycerides
2. Monounsaturated Fats
Olive oil
Canola oil
Peanut oil
Margarine made with canola oil or other highly monounsaturated fat
Olive Oil

13. 3 Types of Triglycerides
Polyunsaturated Fats
Safflower oil
Corn oil
Soybean oil
Sesame oil
Sunflower oil
Nuts and seeds

14. Trans Fatty Acids = Trans Fats
Occur naturally at low levels in meat and dairy foods
Trans fats we eat are often due to hydrogenation of vegetable oils to make shortening, margarine, and fats for frying
Trans fats raise blood cholesterol levels as much as saturated fat

15. Main Contributors to Trans Fats in Diet
Cakes, cookies, pies, bread, etc.
Animal products
Margarine
Fried potatoes
Potato chips, corn chips, popcorn
Household shortening

16. Essential Fatty Acids
Linoleic acid is an omega-6 fatty acid found in vegetable oils, whole grains, and vegetables.
Alpha-linolenic acid is the leading omega-3 fatty acid found in food, and it is found in canola, flaxseed, soybean, walnut, and wheat germ oils. Ground flaxseed is rich in alpha-linolenic, and walnuts are also a good source.
Americans get more than enough linoleic, but not enough alpha-linolenic.

17. DHA and EPA
The body converts alpha-linolenic into DHA and EPA (also omega-3s) but the process is very slow, resulting in little DHA/EPA.
DHA and EPA are found in fatty fish such as salmon and mackerel – AHA recommends eating fatty fish twice/week.
DHA and EPA are VERY heart healthy.

18. Essential Fatty Acids (cont’d)
Both EFAs:
Are vital to normal growth and development in infants and children
Maintain the structural parts of cell membranes
Have a role in the proper functioning of the immune system
DHA and EPA are especially important for proper brain and eye development during pregnancy and infancy

19. Cholesterol An odorless, white, waxy, powdery substance
Cholesterol is present in every cell in your body. It is needed to make
bile acids
cell membranes
many hormones (such as sex hormones)
vitamin D.

20. Cholesterol (cont’d)
Cholesterol is found only in foods of animal origin: egg yolks, meat, organ meats, poultry, fish, milk, and milk products. Lower-fat milk products contain less cholesterol than full-fat milk products.

21. Cholesterol (cont’d)
4 ounces of meat, poultry, or fish contains 100 mg of cholesterol (except for shrimp).
We take in about 200 to 400 milligrams of cholesterol daily and the liver and body cells also make cholesterol (about 700 milligrams), therefore it is not an essential nutrient.

22. Digestion, Absorption, & Metabolism
Mouth – Lingual lipase
Stomach – Gastric lipase
Intestine
Bile acids
Pancreatic lipase
Intestinal lipase
Once absorbed, triglycerides are reformed

23. Lipoproteins
Protein-coated packages that carry fat and cholesterol through the bloodstream
Chylomicron
Very low-density lipoprotein (VLDL)
Low-density lipoprotein (LDL)
High-density lipoprotein (HDL)

24. Lipids and Health Heart disease
Too much circulating cholesterol leads to plaque and atherosclerosis – as arteries become narrowed, increased chance of heart attack and stroke
Main source of cholesterol buildup: LDL

25. Lipids and Health (cont’d.)
What affects blood cholesterol levels?
Saturated fat, trans fat, and cholesterol in diet
Mono- and polyunsaturated fat in diet
Weight
Physical activity
Age and gender
Heredity

26. Lipids and Cancer
Cancer is the second leading cause of death in the U.S.
Fat may be involved in certain cancers such as prostate cancer.

27. Dietary Recommendations for Fat
No RDA or AI for total fat (except for infants), saturated fat, cholesterol, or trans fats.
AMDR for total fat
1–3 years old % of kcal
4–18 years old % of kcal
Over 18 years old % of kcal
AI set for essential fatty acids
DGA and AHA recommend 10% or less from sat. fat, less than 300 mg of cholesterol daily, and replace sat fats with poly and mono fats such as fish and nuts.
If fat intake is higher than 30%, use monounsaturates.

28. Percentage of Kcal From Fat & Percentage of Fat By Weight
Percentage of kcalories from fat
27 kcal from fat x 100 = 19 percent
140 kcal
Percentage of fat by weight

29. Ingredient Focus: Milk, Dairy & Eggs
Cheese
Eggs

30. Culinary Science Fat in milk is homogenized
To make whipped cream, you need a cream with at least 30% fat
What happens when you whip cream for too long?
Milk, eggs, and cheese are generally cooked at low to moderate heat

31. Culinary Science: Rancidity
Deterioration of fat, resulting in undesirable flavors and odors
Saturated fats are more resistant to rancidity than unsaturated fats
Rancidity is hastened by heat and ultraviolet light
To prevent rancidity, store fats and oils tightly sealed in cool, dark places

32. Food Facts: Oils & Margarines
Butter and margarine must contain at least 80% fat by weight
Types of oils
Olive oil: extra virgin or virgin, pure, light
Margarines vary by:
Physical form
Type of oil
Percent fat by weight

33. Hot Topic: Trans Fats in Restaurants
Laws in certain cities have phased out trans fats in many restaurants
Pros and cons

34. Copyright ©2010 John Wiley & Sons, Inc.
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