jimtrue.com : school : HS1322 : CH04: Lipids: Fats and Oils

Posted by Jim True on November 19, 2009 10:24 AM. Last Updated November 19, 2009 10:24 AM

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CH04: Lipids: Fats and Oils

4 and 11 Quiz next week; 6, 7 and 10 Final

Chemical compound contains fats, oils, cholesterol and leithin

Functions of Lipids

Insulation: provides temperature barrier between body and skin, adipose
Cushion around critical organs
Provides energy (adipose cells = compact energy storage)
Protein-sparing: last resort of energy burning is protein, so fat prevents us from going to the proteins from burning
Part of all cell membranes
Transport of fat-soluble vitamins, such as vitamin a, d, e and k
Essential fatty acids: 2 Lenoleic acid (omega 6) alpha lenoleic acid (omega 3)
Fats account for 13-30% of a person's weight
Fats used to maintain structure of body parts
Fats functions satiety value (satisfy hunger)

In food, fat enhances

Taste
Flavor
Aroma
Crispness
Juiciness
Tenderness
Smooth texture
Creamy feeling
Feeling full

Triglyceride

Some type of fats in foods and some plants
Composed of Glycerol and 3 Fatty Acids
Differentiate Fatty Acids by the length of the carbon chain and the degree of saturation
Saturation: carbons saturated with hydrogen
COOH: Carbolyxic acid

Types of Fatty Acids

Saturated Fatty Acid: Stearic Acid
Monounsaturated fatty acid: oleic acid, 1 point of unsaturation
Polyunsaturated fatty acid: linoleic acid, more than one point of unsaturation
Short fatty acid chain: of 6 carbons or less
Medium fatty acid chain: 6-10 carbons
Long fatty acid chain: 12-24

Lecithin

a phospholipid
vital component of cell membranes
acts as an emulsifier

Triglycerides in Food

Fats, oils and condiments contain most triglycerides
Meat, poultry & fish
Dairy foods
All fats in foods contain a mixture of saturated and unsaturated fats
Oil is from plants liquid at room temperature; fats are from animals, solid at room temperature
Fruits and vegetables almost no fat: except for olives, coconuts, avocado
Breads, cereals, rice, grains, most low in fat except for: biscuits, crackers, croissants
Dry beans, peas, nuts and seeds, usually low in fats, except for: nuts are high in fat and some seeds
Meats and poultry and fish are high in fat, depends upon the cut
Dairy products are also high in fat usually

Fats, oils and condiments are almost pure fat

3 Types of Triglycerides

Saturated Triglycerides, saturated fat

Animal foods
cheese
whole milk
fats in baked goods
butter
Coconut, palm kernel and palm oils

Monounsaturated Fats

Olive oil
canola oil
Peanut oil
margarine made with canola oil or other highly monounsaturated fat

Polyunsaturated fat

Safflower oil
corn oil
soybean oil
Sesame oil
sunflower oil
nuts and seeds

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
Examples: french fries, snack foods, baked goods, chips, popcorn, under Total Fat on the nutrition label

Main Contributors to Trans Fats in Diet

Cakes, cookies, pies, bread, etc
Animal products
Margarine
Fried potatoes
Potato chips, corn chips, popcorn
Household shortening

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
American get more than enough linoleic, but not enough alpha-linolenic

DHA and EPA

The body converts alpha-linolenic (ALA) into DHA (Docosahexaenoic acid) and EPA (eicosapentaenoic acid, also omega-3's), 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 (American Heart Association) recommends eating fatty fish twice/week
DHA and EPA are VERY heart healthy, meaning reducing high blood pressure, reducing blood clots, reducing heart rate and reduce TG (Triglyceride) Levels
Both EFA's:
- 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

Cholesterol

an odorless, white, waxy, powdery substance
Cholesterol is present in every cell in your body, it is needed to make: NEED TO KNOW for QUIZ

Bile acids (digestion of fats)
cell membranes
many hormones (such as sex hormones)
Vitamin 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
4 ounces of meat, poultry or fish contains 100mg of cholesterol (except for shrimp) (almost all shellfish have high level of cholesterol)
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

Lipoproteins

Protein-coated packages that carry fat and cholesterol through the bloodstream

Chylomicron and Very low-density lipoprotein (VLDL): absorption of lipids happen in the intestine and carry triglycerides and cholesterol and take it through the blood stream, lipoprotein lipase, starts to break down TG and Ch. Take it to the liver; VLDL converted to LDL in Liver
Low density lipoprotein (LDL)
High-density lipoprotein (HDL): Cleans up extra LDL, etc out of bloodstream, picks up LDL and Cholesterol
Women: HDL 45-50mg/dl, 55-60 for Men LOW range, higher is better

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
What effects blood cholesterol levels?

Saturated fat, trans fat, and cholesterol in diet
Mono- and polyunsaturated fat in diet
Weight
Physical activity
Age and gender
Heredity

Lipids and Cancer

Cancer is the 2nd leading cause of death in the US
Fat may be involved in certain cancers such as prostate cancer

Dietary Recommendations for Fat

No RDA or AI (adequate intake) for total fat (except for infants), saturated fat, cholesterol or trans fat
1-6 31 g/day, 7-12 m, 30g/day

AMDR (accepted macronutrient distribution range) for total fat:

1-3 y.o: 30-40% kcal

4-18 yo: 25-35% kcal

over 18: 20-35% kcal

AI set for essential fatty acids
DGA (Dietary Guidelines for Americans) 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 mono-unsaturates

Percentage of KCal rom Fat & Percentage of Fat by Weight

Percentage of KCAl from fat: 27 kcal from fat x 100 = 19 percent, 140kcal
Percentage of Fat by Weight

Ingredient Focus: Milk, Dairy & Eggs

Milk: good source of protein, carbohydrate, riboflavin (Vitamin B6), vitamin A & D
Cheese: excellent source of proteins and calcium, also high source of saturated fats
Eggs: high source of protein and cholesterol, one egg = 215 mg cholesterol, some types of minerals and vitamins

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? butter and buttermilk
Milk, eggs and cheese are generally cooked at low to moderate heat (to keep it from curdling)

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

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

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