1. Lipids: Fats & Oils

2. Lipids

3. Lipids Lipids are composed of C, H, O Diverse group fats Fixed oils
are esters of long-chain fatty acids and alcohols
Diverse group
fats
Fixed oils
Waxes

4. dehydration synthesis
Fat and Fixed oil
Structure:
glycerol (3C alcohol) + fatty acid
fatty acid = long HC “tail” with COOH group at “head”
enzyme
Note functional group = carboxyl
dehydration synthesis

5. Building Fats Triacylglycerol 3 fatty acids linked to glycerol
ester linkage = between OH & COOH

6. Dehydration synthesis
enzyme
enzyme
enzyme

7. Structure of Fatty Acids
The “tail” of a fatty acid is a long hydrocarbon chain, making it hydrophobic. The “head” of the molecule is a carboxyl group which is hydrophilic. Fatty acids are the main component of soap, where their tails are soluble in oily dirt and their heads are soluble in water to emulsify and wash away the oily dirt. However, when the head end is attached to glycerol to form a fat, that whole molecule is hydrophobic.

8. Saturated fats All C bonded to H No C=C double bonds
long, straight chain
most animal fats
solid at room temp.
contributes to cardiovascular disease (atherosclerosis) = plaque deposits

9. Unsaturated fats C=C double bonds in the fatty acids plant & fish fats
vegetable oils
liquid at room temperature
The double bonded C prevent the molecules from packing tightly together

10. Saturated vs. unsaturated

11. Chemical constants Acid Values Saponification Value Ester Value
Iodine Value
Unsaponifiable Matter

12. ACID VALUE
Refers to the number of mg of KOH needed to neutralize the free acids in 1 g of oil.
-High acid values occur in oils which are rancid.
- Pharmaceutical oil must not have any acidity.
Significance
Acid value is the measure of hydrolytic rancidity. In general, it gives an indication about edibility of the lipid.
Rancid زنخ

13. SAPONIFICATION VALUE
The hydrolysis reaction of lipids (with KOH above) can be used to determine the saponification value of the oil.
Saponification value is expressed as the number of mg of KOH needed to neutralize the free acids in, and to hydrolyse the esters in, 1 g of the substance (oil).

14. ESTER VALUE
Ester value: The difference between the saponification and acid values.

15. IODINE VALUE Iodine value:
Gives the measurement of the unsaturation of the oil. The higher the iodine number, the more unsaturated fatty acid bonds are present in a fat.
Ex. linseed oil

16. UNSAPONIFIABLE MATTER
The fraction of substances in oil & fat which is not saponified by caustic alkali, but is soluble in ordinary fat solvent is called unsaponifiable matter.

17. UNSAPONIFIABLE MATTER
Unsaponifiable matter consists of compounds such as sterols, which remain after saponification of the triglycerides and the removal of the glycerol and soaps (by using solvents).

18. SIGNIFICANCE? These constants are important general tests to ensure
That the oil is genuine
To detect adulteration of fixed oils and fats.

19. ADULTERATION OF FIXED OILS
-Cheap oils are often mixed with more expensive oils as a form of adulteration.
-Three of the most commonly used oils are:
Sesame oil
Cotton seed oil
Arachis oil

20. Examples of valuable fixed oils:
Olive oil
Cod-liver oil

21. OLIVE OIL
Olive oil is the oil expressed from the ripe fruits of Olea europea (Oleaceae Family).

22. OLIVE OIL 1st oil expressed: Virgin oil
Subsequent extractions: marc is solvent extracted – lower quality oil.
Superior grades of oil: Extra-virgin, Virgin, or Refined.

23. OLIVE OIL: CHARACTERISTICS
Olive oil: Pale yellow liquid, sometimes with a green tint.
Oil has a slight odour & nice taste.

24. OLIVE OIL: CONSTANTS
If the fruits used to produce the oil have been allowed to ferment, the acid value will be higher than is officially permitted.

25. OLIVE OIL: CONSTITUENTS
Oils from different sources differ slightly in their constituents (composition).
This result may be due to the different varieties of olive used, or to climate differences.

26. Type I Type II BP Limits
_______________________
% % %
_________________________________________
Oleic Acid
Linoleic Acid
Palmitic Acid
Stearic Acid

27. COD-LIVER OIL DEFINITION:
Medicinal cod-liver oil is a fixed oil prepared from the fresh liver of the cod, Gadus callarias, & other Gadus spp. (Gadidae Family), under conditions which make it palatable & containing a certain amount of Vitamins.

28. COLLECTION & EXTRACTION
Cod-livers (contain 50% oil), are removed immediately after the fish are caught & transferred to steamers & stored at low temperature.

29. STORAGE OF COD-LIVER OIL
Cod-liver oil should be stored in well-fitted airtight containers.
It should be protected from light & stored in a cool, dry place.

30. Rancid oils are a major source of destructive free radicals in our diet. Exposure to air, heat, and light cause oils to oxidize, become rancid, and form free radicals.
Monounsaturated fats, since they have a pair of missing hydrogen atoms are somewhat vulnerable to oxidation. Polyunsaturated oils, which are missing several pairs of hydrogen atoms, are very unstable and highly reactive to oxidation.

31. COD-LIVER OIL: CONSTITUENTS
The oil consists of glycerides of unsaturated (85%) and saturated (15%) acids.
Saturated fatty acids: myristic acid, palmitic acid & traces of stearic acid.

32. ACTIONS & USES
The medicinal properties of cod-liver oil are mainly due to the Vitamins A & D.
It is widely used in underdeveloped countries for the prevention & treatment of rickets.
Europe & USA: Traditionally used as a vitamin supplement.
Recent research: relief of rheumatic pains & joint & muscle stiffness.
Reduces blood cholesterol.
Protects against CVD