1. Triglycerides, Phospholipids, and Sterols
Chapter 5 - LIPIDS
Triglycerides, Phospholipids,
and Sterols

2. TYPES OF LIPIDS
1. Triglycerides
2. Phospholipids
3. Sterols

3. TRIGLYCERIDES Triglycerides – Fats & Oils
1. Predominate form of fat in foods
and major storage form of fat in
the body
2. Structure – composed of 3 fatty
acids + glycerol

4. Fatty Acids
Organic acid (chain of carbons with hydrogens attached) that has an acid group at one end & a methyl group at the other end
Copyright 2005 Wadsworth Group, a division of Thomson Learning

5. Fatty Acids & Triglycerides
glycerol + 3 fatty acids  triglyceride + H2O
Copyright 2005 Wadsworth Group, a division of Thomson Learning

6. FATTY ACIDS Fatty Acids – carbon chains, vary in: 1. Length – affects
absorption
2. Saturation –chemical
structure; affects
cooking & storage
properties and health

7. Stearic acid – 18-carbon, saturated
Length of carbon chain
Stearic acid – 18-carbon, saturated
Simplified structure
Copyright 2005 Wadsworth Group, a division of Thomson Learning

8. FATTY ACIDS Saturation Saturated fatty acid – carbon chains
filled with hydrogen atoms (no C=C
double bonds)
1. Saturated fat – triglyceride
containing 3 saturated fatty
acids, such as animal fats
(butter, lard) & tropical oils
(palm, coconut)
2. Appear solid at room temperature

9. FATTY ACIDS
Unsaturated fatty acid – carbon chains lack some hydrogens (>1 C=C double bond)
1. Monounsaturated fat – triglyceride
containing fatty acids with 1 double
bond; i.e. canola & olive oil
2. Polyunsaturated fat- triglycerides
containing a high % of fatty acids with
>2 double bonds; i.e. corn, safflower,
soybean, sunflower oils and fish; 3. Appear liquid at room temperature

10. Oleic acid – 18-carbon, monounsaturated
Linoleic acid – 18-carbon, polyunsaturated

11. Copyright 2005 Wadsworth Group, a division of Thomson Learning

12. Fatty Acids Location of double bonds
Omega number – refers to the position of the double bond nearest the methyl (CH3) end of the carbon chain
Omega-3 fatty acid
Omega-6 fatty acid
Copyright 2005 Wadsworth Group, a division of Thomson Learning

13. Omega-3 and Omega-6 Fatty Acids Compared
Copyright 2005 Wadsworth Group, a division of Thomson Learning

14. FATTY ACIDS Hydrogenated – addition of hydrogen to unsaturated fat
1. Makes it more “solid” or firm
2. Effects stability and protects
against oxidation; more “shelf-
stable”
3. Widely used by food industry in
margarine, shortening, peanut
butter, baked goods & snack food

15. Hydrogenation
Copyright 2005 Wadsworth Group, a division of Thomson Learning

16. Hydrogenation Cis vs. trans-fatty acids
In nature, most double bonds are
cis meaning that the hydrogens next to the double bonds are on the same side of the carbon chain
When a fat is partially hydrogenated, some of the double bonds change from cis to trans

17. Cis- and Trans-Fatty Acids Compared
Copyright 2005 Wadsworth Group, a division of Thomson Learning

18. PHOSPHOLIPIDS
Phospholipids – similar to triglycerides in structure except only 2 fatty acids + choline
Phospholipids in foods: Lecithin, egg yolks, soybeans, wheat germ, peanuts

19. Lecithin
Copyright 2005 Wadsworth Group, a division of Thomson Learning

20. Phospholipids
1. Functions: part of cell membranes and acts as an emulsifier (helps keep fats in solution)
2. Not a dietary essential; made by the liver

21. Phospholipids
Copyright 2005 Wadsworth Group, a division of Thomson Learning

22. Sterols Structure consists of carbon rings
Copyright 2005 Wadsworth Group, a division of Thomson Learning

23. STEROLS Important part of: 1. Sex hormones – testosterone 2. Vitamin D
3. Bile (aids fat digestion)
4. Adrenal hormones - cortisol
5. Cholesterol – in foods and
made by the liver; dietary
sources include egg yolks,
liver, meats, dairy products

24. Fat Digestion Hydrolysis
Triglycerides  monoglycerides, fatty acids, glycerol
Copyright 2005 Wadsworth Group, a division of Thomson Learning

25. Fat Digestion
Copyright 2005 Wadsworth Group, a division of Thomson Learning

26. Fat Digestion Mouth Melting Lingual lipase Stomach Churning and mixing
Gastric lipase
Copyright 2005 Wadsworth Group, a division of Thomson Learning

27. Fat Digestion Small intestine Pancreatic lipases Intestinal lipases
CCK
Bile and emulsification

28. Emulsification of Fat by Bile
Copyright 2005 Wadsworth Group, a division of Thomson Learning

29. Fat DigestionOverview
Copyright 2005 Wadsworth Group, a division of Thomson Learning

30. Lipid Transport
Lipoproteins – clusters of lipids and proteins that are used as transport vehicles for fat
Chylomicrons
VLDL = very-low-density lipoproteins
LDL = low-density lipoproteins
HDL = high-density lipoproteins
Copyright 2005 Wadsworth Group, a division of Thomson Learning

31. Size & Compositions of Lipoproteins

32. Functions of Fats In the body, fats provide: 1. Energy – 9 kcals/gm
A. Supplies 60% of body’s energy
needs at rest
B. Stored as adipose tissue
2. Insulation & protection
3. Cell membrane constituents

33. Functions of Fats In foods, fats: 1. Provide energy (9 kcal/gm)
2. Contribute flavor, aroma, and tenderness
3. Provide satiety
4. Carry fat-soluble vitamins (A,D,E & K)
5. Provide a source of essential fatty acids

34. Fatty Acids Essential fatty acids – 2 polyunsaturated
fatty acids that must be provided in diet
1. Linoleic – omega-6 fatty acid and
Linolenic – omega-3 fatty acid
2. Founds in plant oils, nuts, seeds, whole
grains and fish
3. Play a role in normal growth &
development and may prevent heart
disease, hypertension, arthritis &
cancer

35. Copyright 2005 Wadsworth Group, a division of Thomson Learning

36. Health Effects of Fats Excess fat intake contributes to many diseases
including:
1. Obesity
2. Diabetes
3. Cancer
4. Heart disease
How?
1. High fat diets = high kcal diets
2. High saturated fat intake raises blood
cholesterol
3. High fat intakes may promote cancer

37. Health Effects of Lipids
Risks from trans fats
Risks from cholesterol
Risks from saturated fats
Copyright 2005 Wadsworth Group, a division of Thomson Learning

38. Saturated Fats in the U.S. Diet

39. Dietary Cholesterol
Copyright 2005 Wadsworth Group, a division of Thomson Learning

40. Health Effects of Lipids
Benefits from monounsaturated fats and polyunsaturated fats
Benefits from omega-6 and omega-3 fats
1. May reduce blood cholesterol
& help prevent cancer
Copyright 2005 Wadsworth Group, a division of Thomson Learning

41. Dietary Recommendations
1. Limit total fat intake to <30% of kcals
Example: If 2000 kcal diet, then
2000 x .30 = 600 kcals/9 kcals per gram = 65 gms of protein
2. Limit cholesterol to <300 mg/day
3. Saturated & polyunsaturated fats each <10% of kcals

42. Cutting Fat Cuts Calories and Saturated Fat
Copyright 2005 Wadsworth Group, a division of Thomson Learning

43. Dietary Recommendations
1. Use all fats in moderation
*1 tsp fat = 5 gm = 45 kcals
2. Beware of “hidden fats” – added to
convenience foods, processed foods, & in cooking
3. Choose lean meats, skinless poultry,
nonfat dairy products; limit meats to <7 oz./day
4. Choose fish 2-3 times/week
5. Choose monounsaturated fats – canola, olive,
peanut, or sesame oils; avoid hydrogenated oils
6. Limit egg yolks to 3-4/week

44. Heart-Healthy Choices
Copyright 2005 Wadsworth Group, a division of Thomson Learning

45. Copyright 2005 Wadsworth Group, a division of Thomson Learning

46. Copyright 2005 Wadsworth Group, a division of Thomson Learning

47. Comparing Butter & Margarine Labels

48. Fat Substitutes Types: Z-Trim; made from plant fibers
1. Carbohydrate based – i.e. Oatrim &
Z-Trim; made from plant fibers
2. Protein based – i.e. Simplesse; made
from egg white or milk protein
3. Fat based – i.e. Olestra; made from
sucrose & fatty acids; passes through
body undigested

49. Fat Substitutes B. Do they work?
1. Potential health benefits – promote
weight loss and lower blood lipids
2. But like sugar substitutes, many people
just eat more instead of replacing fat
3. Side effects possible with Olestra
4. Use in moderation