1. Lipids Part II

2. Physical Properties Energy value Phase Differences Solubility
Melting / solidification points 2

3. Energy
Energy is released when things react with oxygen (burning or combustion)
Triglycerides react well with oxygen
Store energy for long term use
Contain more than twice as much energy as carbohydrates
Digest more slowly than carbs, so they provide a slow steady release of energy 3

4. Phase Differences
Fats that usually come from animals are saturated fats. They are denser than oils and in a solid phase at room temperature.
Most plant oils are unsaturated. The bend in their chemical structures makes oils less compact, so they are liquid at room temperature.
Exceptions include Coconut and Palm Oil, which are over 80% saturated fats.

5. Solubility Fats and oils don’t dissolve in water
An emulsifier can be used to allow them to mix. 5

6. Melting / Solidification
Fats have a temperature range for melting and solidifying
Each fat is a collection of 3 fatty acids, all with different melting / solidification points. 6

7. Fats Used in Food Processing
Hydrogenated Fats
Partially Hydrogenated Fats
Trans Fats

8. Which is healthier?
The top margarine is better for you. It contains more total fat, but less unhealthy (saturated) fat than the bottom one. Remember, it is the saturated fat, not the total fat content, that matters most.
Partially hydrogenated – a process of adding hydrogen to an unsaturated oil to make it partially saturated so it can solidify at room temp. Makes it more useful but less healthy

9. What is Hydrogenation?
the process of adding hydrogen to an unsaturated fat
makes the fat either partially or fully saturated
allows liquid oils to be solidified at room temperature.

10. Why do we use partial hydrogenation?
Very useful for creating things like margarine and shortening.
Has a longer shelf-life than liquid oils
Changes the texture of foods containing oils
Heavy use by the fast-food industry. For example: many restaurant chains use blocks of shortening for deep-frying rather than liquid oil.

11. Hydrogenating vegetable oils results in the creation of trans fats!
Traditionally, baked goods used lard (a saturated animal fat).
However vegetable oils are much cheaper, so processors have switched from lard to partially hydrogenated vegetable oils.
Hydrogenating vegetable oils results in the creation of trans fats!

12. Trans Fats – MAN MADE
These kid of fats are found in fried foods, commercially baked goods, processed foods, and margarine.
These fats elevate bad cholesterol and should be avoided!
Most unhealthy type of fat – causes significant increase in risk of heart disease and other health issues
As little as 1 gram of trans fat a day can double your risk of heart disease.

13. Cis vs. Trans
Unsaturated fats are healthy because the double bond causes the shape of the molecule to bend.
This bent shape is called a “cis” configuration. Fat molecules can’t easily stack.
When an unsaturated fat is “hydrogenated” it is converted to a saturated fat.
Trans fat is a by-product of hydrogenation. There is still a slight bend, but they are much more stackable than “cis” fats.

14. Legislation and Safety
Many jurisdictions are banning or limiting trans fats
Trans fat content is required on food labels in Canada.
Government agencies say there is no safe level of trans fat consumption.
New technologies are allowing for safer methods of partially hydrogenating oils
Alternatively, some processors are switching back to natural saturated fats, like lard.

15. Triglyceride subgroups
Fat on edge of meat and marbling throughout.
Usually high in saturated fats (esp. red meats); some contain oleic acid
Animal fats
Cod liver oil
Long chains of polyunsaturated fatty acids; some very high in vitamins A and D
Fish oils
Corn, peanut, sunflower, olive, and sesame oils
Unsaturated; most common fat in North American diet
Fats containing oleic or linoleic acids
Cocoa butter
Highly saturated
Vegetable butters
Soybean oil, wheat germ oil
Highly unsaturated
Fats containing linolenic acid
Coconut palm oil / palm kernel oil
Usually low in unsaturated fatty acids; high in saturated fatty acids
Fats from the coconut palm
Cow’s milk
Contain some saturated fatty acids
Milk fat
Examples
Description
Triglyceride Subgroup

16. Functions of Fats in Foods
Why do we use fats in foods?
Tenderizing
Aeration
Emulsions
Flavor

17. Tenderizing / Aeration
Since water and fat don’t mix, the fats seal in moisture.
Foods don’t dry out.
Fats also form bubbles around air molecules. This helps baked goods rise and get fluffy.

18. Emulsions
Emulsions – phospholipids (the 2nd category of lipids) can be used to mix oil and water.
Mayonnaise (lecithin)
Thin mints cookies (soy lecithin – this is in everything! )

19. Flavour Fats carry flavour
Margarine, olive oil, bacon fat, etc
Health concern – many low fat foods replace fat with added sugar or salt (Canadians should consume no more than 10% of their total calorie intake as added sugar – this is roughly grams of added sugar).
Hypertension / high blood pressure
Diabetes

21. ISSUE - Spoilage and Rancidity
Fats can spoil and become rancid over time
Why are potato chip bags full of air?
It’s not air! Chip bags contain pure nitrogen.
Why?
Oxygen reacts with fats to make them turn rancid over time.
Vacuum sealing
Bottling / canning

22. 3. Sterols - Cholesterol
Required for making vitamin D and some hormones
Produced in the liver, from glucose and saturated fatty acids
Body produces all you need; most dietary cholesterol is useless
Too much dietary cholesterol leads to heart disease

23. LDL and HDL Low density lipoprotein High density lipoprotein
Transport cholesterol and other molecules through the blood stream.
LDL – allows cholesterol to build up more quickly and gather in arteries
HDL – helps remove cholesterol from bloodstream

24. Omega-3 Fatty Acids Found in many fish (esp. cold water) Heart healthy
Sardines, salmon, tuna, herring are highest
Heart healthy
Make it more difficult for fats to build up in arteries
Links to better brain health
Long term memory
Less degeneration
Fats are essential for the brain and nervous system