2. DEFINITION
• Lipids are organic substances made up of
fatty acids and their naturally-existing
compounds and derivatives
• In nutrition, lipids provide the much
needed CALORIES to “burn” as fuel for
ENERGY, secondary to carbohydrates
• Some micronutrients function well only
in the presence of fats or lipids
3. • Lipids yield fatty acids upon hydrolysis
• They combine with fatty acids to form
esters
• They contain C, H,O,N sometimes K
• Relatively INSOLUBLE IN WATER and
ordinary solvents
• Soluble in nonpolar/organic solvents like
ether, chloroform, acetone, benzene
4.
5. CLASSIFICATION OF LIPIDS
A.SIMPLE LIPIDS
Esters of fatty acids with various
alcohols
1. Neutral fats (glycerol esters)
2. Waxes (esters of higher alcohols)
ex: Cholesterol esters,Vitamin A,D
esters
6. B. COMPOUND LIPIDS
1. Lipids that contain other radicals such as
Phosphoric acids,or a nitrogenous base
Ex: lecithin, Cephalin, Lipositol
2. Glycolipids- contain Carbohydrate and
Nitrogenous base
3. Ill-defined lipids
amino lipids(Have NH2)
sulfo lipids (have SO4)
7. C. DERIVED LIPIDS
- Lipids that are products of hydrolysis
of simple and compound lipids
1. Saturated and Unsaturated Fatty
acids
2. Mono and Di glycerides
3. Alcohols( sterols and cholesterol)
4. Miscellaneous (ex Squalene,
Carotenoids, Vitamins D, E, K)
8. FATS
• Are esters of fatty acids with GLYCEROL
• EXAMPLES:
1. Animal fats- Oleic, palmitic, stearic acid
2. Mutton fat- more stearic and less oleic than
pork
3. Butter fat- mainly palmitic and oleic, with small
amounts of butyric acid and caproic acids
4. Human Fat- mostly oleic acid, yellowish tinge is
due to carotene and xanthrophyl pigments
10. APPLICATION OF ITS CHEMICAL
PROPERTIES
A. HYDROGENATION
Hydrogenation converts liquid vegetable oils
into solid or semi-solid fats, such as those
present in margarine. Changing the degree of
saturation of the fat changes some important
physical properties such as the melting range,
which is why liquid oils become semi-solid.
Other advantages: longer shelf life, oxidative
stability, cheaper
11. B. OXIDATION
Oxidative rancidity is associated with
the degradation by oxygen in the air. Via
a free radical process, the double bonds
of an unsaturated fatty acid can undergo
change, releasing volatile aldehydes and
ketones. This process can be suppressed
by the exclusion of oxygen or by the
addition of antioxidants. Oxidation
primarily occurs with unsaturated fats.
12. • When these processes occur in food,
undesirable odors and flavors can result.
In some cases, however, the flavors can
be desirable (as in aged cheeses). In
processed meats, these flavors are
collectively known as warmed over
flavor. Rancidification can also detract
from the nutritional value of the food.
Some vitamins are highly sensitive to
degradation.
13. 3. HYDROLYSIS
Hydrolytic Rancidity
• Hydrolytic rancidity occurs when water splits
fatty acid chains away from the glycerol
backbone in triglycerides (fats). The chemical
term is ester hydrolysis. Usually this hydrolysis
process goes unnoticed, since most fatty acids
are odorless and tasteless. When, however, the
triglyceride is derived from short chain fatty
acids, the released carboxylic acid can confer
strong flavors and odors. A particular problem
arises with butter, which contains triglycerides
with a high content of butyric acid derivatives.
14. 4.SAPONIFICATION
This is a process that produces soap, usually
from fats and lye. In technical terms,
saponification involves base (usually caustic
soda NaOH) hydrolysis of triglycerides, which
are esters of fatty acids, to form the sodium
salt of a carboxylate. In addition to soap, such
traditional saponification processes produces
glycerol. "Saponifiable substances" are those
that can be converted into soap.
16. FATTY ACIDS
A. SATURATED
fatty acids composed of single bonds
and are usually solid at room
temperature
These are fats from animal sources
Butter, lard
17.
18. B .UNSATURATED FATTY ACIDS
fatty acids that are composed of
one or more double bonds
They are usually liquid at room
temperature
“OILS” are mostly from plant
sources
Olive oil, corn oil, linseed oil, palm
oil
19.
20. OTHER IMPORTANT FATTY ACIDS
1. Omega Fatty acids (polyunsaturated)
Main source: Fish and Fish oil
2. Linoleic,Linolenic, Arachidonic Acid
Sources: Nuts, Plant oils
** These are not readily produced by the body,
defficiency may lead to impaired growth and
reproduction, eczema,dermatitis,excessive
thirst, kidney damage
21. FUNCTIONS OF FATS IN THE BODY
1.Vitamins A, D, E, and K are fat-soluble,
meaning they can only be digested,
absorbed, and transported in conjunction
with fats. Fats are also sources of
essential fatty acids, an important dietary
requirement.
22. 2. Fats play a vital role in maintaining
healthy skin and hair, insulating body
organs against shock, maintaining
body temperature, and promoting
healthy cell function.
23. 3. Fats also serve as energy stores for
the body, containing about 37.8
kilojoules (9 calories) per gram of fat.
They are broken down in the body to
release glycerol and free fatty acids.
The glycerol can be converted to
glucose by the liver and thus used as
a source of energy.
24. 4. Fat also serves as a useful buffer towards a host
of diseases. When a particular substance,
whether chemical or biotic—reaches unsafe
levels in the bloodstream, the body can
effectively dilute—or at least maintain
equilibrium of—the offending substances by
storing it in new fat tissue. This helps to protect
vital organs, until such time as the offending
substances can be metabolized and/or removed
from the body by such means as excretion,
urination, accidental or intentional bloodletting,
sebum excretion, and hair growth.
25. ***While it is nearly impossible to remove
fat completely from the diet, it would
also be unhealthy to do so. Some fatty
acids are essential nutrients, meaning
that they can't be produced in the body
from other compounds and need to be
consumed in small amounts. All other
fats required by the body are non-
essential and can be produced in the
body from other compounds
