1. TRIGLYERIDES
AIMS:
•Be able to define all terms involved in the making of “healthy
alternatives to butter”;
•Understand processes involved in production of alternatives;
•Know the pros and cons of butter alternative and biofuels
produced by trans-esterification.

2. Some definitions
1. Triglycerides
• esters of glycerol (propane-1,2,3-triol) with 3 carboxylic
acids;
• carboxylic acids do not need to be the same;
H
O
H C O C R
O
H C O C R’
O
H C O C R’’
H
1
2
3
1.from glycerol
2.3 ester links
3.from fatty acids

3. 2. Fatty acids
– Naturally occurring carboxylic acids in triglycerides
– The acids contain long hydrocarbon chains
3. Saturated fatty acids
– No double bonds in acids
4. Fats
– Solid at room temperature
– Contain high proportion of saturated fatty acids
5. Unsaturated fatty acids
– One or more C=C in each molecule
– Less regular structure than fatty acids
– Generally liquid at room temperature

4. Olive oil
80% oleic acid
10% linoleic acid
Cis-octadec-9-enoic acid
CH3(CH2)7CH=CH(CH2)7COOH
cis,cis-octadec-9,12-dienoic acid
CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH
**NOW TRY DRAWING SKELETAL FORMULA**

5. SOAPS
• Mixture of animal fat and coconut palm oil;
• If mainly animal fat
– Less soluble
– Longer lasting
• If mainly palm oil
– More soluble
– Lather quickly
– Wash away quickly
**antioxidants added to stop soap and air combining to
make irritant chamicals**

6. HYDROGENATION
Margarine
– cheap substitute for butter
– hydrogen added to veg oils, saturating C=C
– Catalyst is finely turned nickel, suspended in the oil
– Not all C=C required to be broken to make solid
– A blend of oils, some harder than others
– Used as spreads and to make cakes and biscuits

7. Trans-fats
• Naturally occurring fatty acids exist as cisisomers;
• Nickel catalyst causes some to become trans;
• Therefore there is a proportion of trans-fats in
products made using partially hardened oils;
• Growing concerns about trans-fats and poor
health.

8. New production method
• A process that allows triglycerides to swap fatty
acid molecules;
• Result is a product with a high melting point;
• This process allows molecules to pack closer
together, making them denser;
• Process called TRANS-ESTERIFICATION;
• Produces triglycerides not found naturally;
• Catalysts used:
– Sodium methoxide
– lipase

9. TRANS-ESTERIFICATION
• ONE ESTER CONVERTED INTO ANOTHER ESTER
RCO-OR’ + R’’OH
RCO-OR’’ + R’OH
different alkoxy group

10. BIOFUELS
• Trigylerides in veg oils and animal fats
• Heated with methanol or ethanol in presence
of a catalyst base e.g. NaOH in alcohol
• When reaction completed, fatty acids
converted to methyl or ethyl esters and a
glycerol by product.

11. PROS AND CONS OF BIOFUELS
• PROS:
– Used to reduce CO2 emissions;
• CONS:
• They are not carbon neutral:
–
–
–
–
–
–
Clearing land to grow crops e.g. Rain forests!
Manufacture of fertiliser;
Plant cultivation;
Harvesting;
Extraction of oil;
Processing oil to make fuel.
NEW RESEARCH IS DEVELOPING ALTERNATIVES DERIVED
FROM WASTE FOOD CROPS AND GROWING CROPS ON
MARGINAL LAND (NOT SUITABLE FOR FOOD PRODUCTION)