DEPARTMENT
OF BIOLOGY
FACULTY
OF SCIENCE & MATHEMATICS
UNIVERSITI
PENDIDIKAN SULTAN IDRIS
SBK3013
PRINCIPLE
IN BIOCHEMISTRY
EXPERIMENT 4: LIPID
NAME
|
MATRIC NO.
|
MUHAMMAD FARIS BIN ISMAIL SAZEMI
|
D20141067089
|
MAYURIE PHUTHARANT A/P SURIN
|
D20141067078
|
NUR AFIQAH SYAHMINA BT MOHD KAMAL
|
D20141067091
|
GROUP: A
LECTURER’S NAME: DR. ROSMILAH MISNAN
INSTRUCTOR NAME: NUR ATIEKAH BT AZAHARI
INTRODUCTION
Today
experiment is about lipid and we gone look into the saponification of
triglycerides. Lipids are molecules that contain hydrocarbons and make up the
building blocks of the structure and function of living cells. For examples,
fats, oils, waxes, certain vitamins, hormone and most of the non-protein
membrane of cells. Besides that, lipids are a large and diverse group of
naturally occurring organic compounds that are related by their solubility in
non-polar organic solvents and general insolubility in water. The
tri-esters of fatty acids with glycerol (1, 2,3-trihydroxypropane) compose the
class of lipids known as fats and oils. These triglycerides are found
in both plants and animals, and compose one of the major food groups of our
diet. Triglycerides that are solid or semisolid at room temperature are
classified as fats, and occur predominantly in animals. Those triglycerides
that are liquid are called oils and originate chiefly in plants, although
triglycerides from fish are also largely oils. The process of
saponification, by heating a triglyceride in aqueous potassium hydroxide (KOH)
the fatty acyl esters can be cleaved off (hydrolysis) leaving behind glycerol
and the potassium salt of the fatty acid. So, the triglycerides that contain
high fatty acids number will have a lower saponification number that
triglycerides with low fatty acids number.
MATERIAL
Triglyceride
sample (sunflower oil, corn oil, palm oil, margarine and butter)
Solvent
( 1:1 ethanol/ether)
0.5
M KOH/ ethanol solution
Phenolphtalein
0.5
M HCL
PROCEDURE
1.
1.0 g of the sample triglyceride is placed
to a small beaker and 4 ml of solvent is dissolved (solvent is 1:1 ethanol /
ether).
2.
The dissolved triglycerides is transfer to
a small distillation flask and the beaker is washed twice with 1 ml of solvent
(1:1 ethanol/ether) to collect all residual material. The "wash" is
added to the distillation flask.
3.
25 ml of 0.5M KOH /ethanol solution is
added
4.
The exact volume of mixture is measured.
5.
A second system as a "Control"
(or reference) was set up with 25 ml of the 0.5M KOH/ethanol solution plus 2 ml
of 1:1 ethanol/ether solvent for a final volume identical to the test sample
solution.
6.
A reflux condenser is set up on each flask
and place heater for 30 minutes. The hydrolysis will occur during this period.
7.
Figure shows hydrolysis process
8.
The flasks is allowed to cool. Three drops
of indicator solution was added (phenolphthalein, 10 g/L) to both flasks and
titrated with 0.5M HCl solution.
9.
Figure show the titration process
10.
The saponification number for tested
samples was calculated by using the given formula.
11.
The molar difference between the amount
of 0.5M HCl required to neutralize the "Control" and the amount of
HCl required to neutralize the test sample equals the amount of 0.5M KOH used
in the saponification process.
12.
The weight (mg) of KOH used to
saponify the 1 g sample was calculated. The saponification number for tested
samples was calculated
13.
The final results from the other
groups was obtained for each sample and a table to summarize the results was
prepared.
RESULT
Sample
|
B (ml)
|
T (ml)
|
Saponification Number
|
Sunflower oil
|
22.2
|
21.0
|
33.7
|
Corn oil
|
23.0
|
22.0
|
28.1
|
Margarine
|
23.0
|
20.0
|
84.2
|
Butter
|
28.0
|
25.0
|
84.2
|
25.0
|
21.5
|
98.2
|
|
22.5
|
22.0
|
14.0
|
|
Palm oil
|
23.0
|
22.0
|
28.1
|
|
- Saponification number: The mass of KOH in
milligram (mg) that is required to saponify 1 gram of fat.
- B = volume (ml) of 0.5 mol/l HCl consumed in the
blank test (Initial volume HCl-final volume HCl)
- T = volume (ml) of 0.5 mol/l HCl consumed in the
sample test (Initial volume HCl-final volume HCl)
- Molecular weight of KOH (MW KOH)= 56.11 g/mol
- Molar of KOH (M) = 0.5 mol/L
- Sample weight (g) = 1 g
Calculation for saponification number
Sample
|
B (ml)
|
T (ml)
|
Saponification Number
|
Sunflower oil
|
22.2
|
21.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
= (22.2-21.0)
x 0.5 X 56.11/1
= 33.7
|
Corn oil
|
23.0
|
22.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
= (23.2-22.0) x 0.5
X 56.11/1
= 28.1
|
Margerine
|
23.0
|
20.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
=
(23.0-20.0) x 0.5 X 56.11/1
= 84.2
|
Butter
|
28.0
|
25.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
=
(28.2-25.0) x 0.5 X 56.11/1
= 84.2
|
25.0
|
21.5
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
=
(25.0-21.5) x 0.5 X 56.11/1
= 98.2
|
|
22.5
|
22.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
=
(22.5-22.0) x 0.5 X 56.11/1
= 14.0
|
|
Palm oil
|
23.0
|
22.0
|
Saponification Number = (B-T) X M of KOH X MW KOH /
Sample weight (g)
=
(23.0-22.0) x 0.5 X 56.11/1
= 28.1
|
DISCUSSION
In this experiment, we are able to determine the
saponification number for each sample tested. Saponification value (sap) or
also known as saponification number represents the number of milligrams of
potassium hydroxide (KOH) required to saponify 1g of fat under the conditions
specified. It measures the average molecular weight of all the fatty acids
present. The smaller the molar mass of the fat, the higher the saponification
value.
In this experiment we obtained that there are three
different values of saponification number for butter that we get from three
different groups. There are slight
different between the readings which are 84.2, 98.2 and 14.0 respectively.
There are huge different between the readings due to technical errors. This
might due to addition of too much phenolphthalein into the sample solution.
Secondly, the readings are not taken immediately after the solution turned
colorless. Butter fat is made out of a majority of short chained fatty acids,
hence it should have high number of saponification value.
Margarine have higher number of saponification value
which is 84.2, followed by sunflower oil sap value of 33.7, corn oil sap value
of 28.1 and palm oil sap value of 28.1.
Theoretically triglycerides containing long fatty acids will have a lower
saponification number than triglycerides with shorter fatty acids. Low fatty
acid fats like coconut oil or palm oil fat will have high saponification value.
On the other hand vegetable oils like sunflower oil will have a lower
saponification number. It means that, palm oil have the shorter fatty acid
chain than corn oil and sunflower oil. For the palm oil and corn oil, the
saponification number should higher than sunflower oil because they have
shorter fatty acid chain than sunflower oil. Due to errors during experiment,
the results obtained were totally different from what we expected. The amount
of phenolphthalein dropped into the solution might be too much or too little
hence it alters our value of amount of HCL.
CONCLUSION
From the experiment that have been conducted, substances that have the
higher number of saponification is butter and the least saponification number
also butter. We can say that the result is not accurate because the result from
butter is from three different group and all the group get the different
saponification number. We can say that there may have some mistake during the
process.
REFERENCES
Zumdahl, Steven S.
(2009). Chemical Principles (6th ed.).
New York: Houghton Mifflin Company
Hill, J.W.; Petrucci,
R.H.; McCreary, T.W.; Perry, S.S. (2005). General
Chemistry (4th Ed.). Upper Saddle River, New Jersey: Pearson Prentice Hall.
Fromm, H. J.& Hargrove, M. (2012). Essentials of Biochemistry. Pearson Education
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