Transcript Chapter 4 - Fernando Haro

Chapter 4
Lipids: Fats and Oils
1
Learning Objectives
1.
2.
3.
4.
5.
6.
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
Learning Objectives (cont’d)
7.
8.
9.
10.
11.
12.
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
Lipids
 Fats
 Oils
 Cholesterol
 Lecithin
4
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
5
In food, fat enhances:
 Taste
 Smooth texture
 Flavor
 Creamy feeling
 Aroma
 Feeling full
 Crispness
 Juiciness
 Tenderness
6
A Triglyceride
7
Types of Fatty Acids
Point of
Unsaturation
8
Lecithin
 A phospholipid
 Vital component
of cell
membranes
 Acts as an
emulsifier
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.
10
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
11
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
12
3 Types of Triglycerides
3.
Polyunsaturated Fats






Safflower oil
Corn oil
Soybean oil
Sesame oil
Sunflower oil
Nuts and seeds
13
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
14
Main Contributors to
Trans Fats in Diet
 Cakes, cookies, pies, bread, etc.
 Animal products
 Margarine
 Fried potatoes
 Potato chips, corn chips, popcorn
 Household shortening
15
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 alphalinolenic, and walnuts are also a good source.
 Americans get more than enough linoleic, but
not enough alpha-linolenic.
16
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.
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
18
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.
19
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.
20
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.
Digestion, Absorption, & Metabolism
 Mouth – Lingual lipase
 Stomach – Gastric lipase
 Intestine



Bile acids
Pancreatic lipase
Intestinal lipase
 Once absorbed, triglycerides are reformed
22
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)
23
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
24
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
25
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.
26
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
4–18 years old
Over 18 years old
30-40% of kcal
25-35% of kcal
20-35% 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.
27
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
28
Ingredient Focus: Milk, Dairy & Eggs
 Milk
 Cheese
 Eggs
29
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
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
31
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
Hot Topic: Trans Fats in Restaurants
 Laws in certain cities have phased out trans
fats in many restaurants
 Pros and cons
Copyright ©2010 John Wiley & Sons, Inc.
Clip art images may not be saved or downloaded and
are only to be used for viewing purposes.
34