SBL 1023
Technique in Biology And
Biochemistry Laboratory
Lab 4: LIPID ANALYSIS
AYU ILYANA BT ZULKIFLI
STUDENT`S NAME
( E20161014077)
GROUP B
EXPERIMENT`S NO LAB 4 : LIPID ANALYSIS
DATE/DAY/PLACE 5/12/2017 /TUESDAY/ B2-L3-MP 14
LECTURE`S NAME Professor Madya Dr. Shakinaz Binti Desa
1.0 INTRODUCTION
Lipids are classified as organic compounds that are soluble in organic solvents, but only
sparingly soluble in water. Lipids are biologically important for making barriers that is membranes of
animal cells, which control the flow of water and other materials into a cell. There are several classes
of lipids, including fatty acids, waxes, triacylglycerol, phospholipids and steroids. The fatty acids are
usually not free in nature, but are components of triacylglycerol, waxes, and phospholipids.
Fatty acids are generally long, straight chains of carbon atoms with hydrogen atoms attached
(hydrocarbons) with a carboxylic acid group (COOH) at one end and a methyl group (CH3) at the other
end. These long, straight chains combine with the glycerol molecule to form lipids (glycerol lipids).
Most naturally occurring fatty acids contain an even number of carbon atoms. The 18-carbon fatty
acids are the most abundant in our food supply, examples are linoleic acid (an omega-6 fatty acid)
found in corn oil and linolenic acid (an omega-3 fatty acid) found in flaxseed oil.
Phospholipids, such as lecithin, have a polar or charged portion and a nonpolar portion
consisting of the long chain fatty acids within the same molecules. Consequently the polar charged
portion of these molecules will mix with water and the nonpolar portion repels the water but mixes
with lipids.
Figure 1.0. Structure of lecithin.
Figure 1.1. Solubility of lipid in organic solvent
2.0 OBJECTIVE
To determine present of lipid in food sample
To determine solubility of lipid in organic solvent
To determine percent of lipid by extraction the lipid and weighing it.
3.0 MATERIALS
Food samples (potato chips, chocolate chips, sunflower seeds, biscuits)
Petroleum ether
Deionised water
Test tubes and test tube rack
Measuring cylinder
Dropper and spatula
Erlenmeyer flask.
Beaker
Weighing scale
Hot plate
4.0 METHODOLOGY
(A) Extraction of lipids from foods.
1. Food sample such as potato chips, sunflower seed and cookies has been weighed about 2 gram.
2. Food sample has been crushed into small pieces used mortar and pestle.
3. Empty beaker with a glass rod inside the beaker was weighed and the data was recorded in Table
1.0.
4. The crushed food sample was placed in the beaker.
5. The beaker (with a glass rod) that contained the crushed food has been weighed and data was
recorded in Table 1.0.
6. 10 ml of petroleum ether has been added to the flask contained the crushed food. Then, the crushed
food with petroleum ether was stirred with the glass rod for 5 minutes to get the lipids to dissolve in
the petroleum ether.
7. The petroleum ether was carefully decant from the beaker.
8. The beaker containing the remaining solid food has been placed on a hot plate to evaporate all of
the petroleum ether.
9. After all of petroleum ether was evaporated, the smell characteristics of the petroleum ether was
checked until no longer strong smell , and then, allowed the beaker to cool.
10. The beaker and remaining food has been weighed again (with the glass rod) after the beaker has
cooled to room temperature. Then, the weigh has been recorded in Table 1.0
11. By using Table 2, the mass of lipid extracted from the food sample was calculated and the weight
percent of lipid in that food has been determined.
5.0 DATA AND CALCULATION
5.1 DATA ANALYSIS
Weighed of
Weight of Weight lost
Weight of beaker
beaker from food
empty with Weighed of
Food with dried (weight of % lipid
beaker crushed crushed
sample food (with lipid extraction
(with glass raw food raw food, g
glass rod), extracted) ,
rod) , g (with glass
g g
rod) , g
Biscuits 68.609 70.617 2.008 70.367 0.249 12.40
Potato chips 75.977 78.017 2.040 77.525 0.492 24.12
Sunflower
70.598 72.672 2.074 71.959 0.713 34.38
seeds
Table 1.0. Extraction of lipid
Weighed new beaker Weight of beaker
Food sample without decant with dried decant % lipid
petroleum ether , g petroleum ether, g
Biscuits 46.570 46.575 0.01
Potato chips 47.162 47.617 0.96
Sunflower seeds 40.072 40.649 1.42
Table 2.0. % lipid
(% lipid extraction = weight of lipid extracted/weight of crushed food sample x 100%)
5.2 CALCULATION
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑙𝑖𝑝𝑖𝑑, 𝑔
% 𝑙𝑖𝑝𝑖𝑑 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 𝑥 100%
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑝𝑜𝑙𝑎𝑟𝑖𝑧𝑒𝑑 𝑓𝑜𝑜𝑑 𝑠𝑎𝑚𝑝𝑙𝑒
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ 𝑙𝑖𝑝𝑖𝑑 − 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑙𝑖𝑞𝑢𝑖𝑑
% 𝑙𝑖𝑝𝑖𝑑 = 𝑥 100%
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ 𝑙𝑖𝑝𝑖𝑑
Sample A, Biscuits Sample B, Potato chips Sample C, Sunflower seeds
% lipid extraction
% 𝑙𝑖𝑝𝑖𝑑 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛 % 𝑙𝑖𝑝𝑖𝑑 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛 % 𝑙𝑖𝑝𝑖𝑑 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛
0.2493 𝑔 0.492 𝑔 0.713 𝑔
= 𝑥 100% = 𝑥 100% = 𝑥 100%
2.008 𝑔 2.040 𝑔 2.074 𝑔
= 12.40 % = 24.12 % = 34.38 %
% lipid
% 𝑙𝑖𝑝𝑖𝑑 % 𝑙𝑖𝑝𝑖𝑑 % 𝑙𝑖𝑝𝑖𝑑
46.575 − 46.570 47.617 − 47.162 40.649 − 40.072
= 𝑥 100% = 𝑥 100% = 𝑥 100
46.575 47.617 40.649
= 0.01 % = 0.96% = 1.42%
Table 3.0. Calculation of % lipid extraction and % lipid
6.0 RESULT AND DISCUSSION
6.1.0 GRAPH
BAR GRAPH : FOOD SAMPLE AND % LIPID
EXTRACTION
SUNDFLOWER SEED 34.38
FOOD SAMPLE
POTATO CHIPS 24.12
BISCUIT 12.4
LIPID EXTRACTION PERCENTAGE (%)
Graph 1.0. Food sample and % lipid extraction
6.1.1 DIAGRAM
Sample B Sample C Sample A
Potato chips contained Sunflower seed contained Biscuits contained
24.12 % of lipid extraction 34.48 % of lipid extraction 12.40% of lipid
extraction
Figure 2.0. Sample A, sample B and sample C
6.2 DISCUSSION
In this lab, we using solvent extraction technique to isolating lipids from foods and determine
the total lipid content of foods. This is because, the fact that lipids are soluble in organic solvents, but
insoluble in water, provides the food analyst with a convenient method of separating the lipid
components in foods from water soluble components, such as proteins, carbohydrates and minerals.
To do so, firstly the food sample must been finely ground prior to solvent extraction to
produce a more homogeneous sample and to increase the surface area of lipid exposed to the solvent.
Grinding is often carried out at low temperatures to reduce the tendency for lipid oxidation to occur.
Next, the ideal solvent for lipid extraction would completely extract all the lipid components
from a food, while leaving all the other components behind. In practice, the efficiency of solvent
extraction depends on the polarity of the lipids present compared to the polarity of the solvent. Polar
lipids such as glycolipids or phospholipids are more soluble in polar solvents such as alcohols, than in
non-polar solvents. On the other hand, non-polar lipids such as triacylglycerols are more soluble in
non-polar solvents such as hexane than in polar ones.
The fact that different lipids have different polarities means that it is impossible to select a
single organic solvent to extract them all. Thus the total lipid content determined by solvent extraction
depends on the nature of the organic solvent used to carry out the extraction, the total lipid content
determined using one solvent may be different from that determined using another solvent. In
addition to the above considerations, a solvent should also be inexpensive, have a relatively low
boiling point, be non-toxic and be non-flammable. Thus, petroleum ether are the most commonly
used solvents to dissolve in non-polar lipid. How petroleum ether can dissolved in lipid? Petroleum
ether can dissolved in lipid because petroleum ether is a common solvent that is a mixture of non-
polar hydrocarbons. Lipid are also nonpolar hydrocarbons. The saying "like dissolves like" works here
for predicting that lipid are soluble in petroleum ether.
Next, when the lipid from food sample dissolve in a petroleum ether. This cause 2 layer form,
one layer for solid precipitate of food sample and a solution layer. The solid precipitate is a lipid that
has been extracted. While, the solution contain petroleum ether and lipid was pour to another beaker,
then heated, when it heated, the petroleum ether lost as a gas, this, will cause only lipid present in
the beaker, same with the beaker which contained lipid extraction. Thus, after determine the lipid
present, we can calculate the percent of lipid extraction and percent of lipid through some at
calculation. Using this formula:
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑙𝑖𝑝𝑖𝑑, 𝑔
% 𝑙𝑖𝑝𝑖𝑑 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 𝑥 100%
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑝𝑜𝑙𝑎𝑟𝑖𝑧𝑒𝑑 𝑓𝑜𝑜𝑑 𝑠𝑎𝑚𝑝𝑙𝑒
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ 𝑙𝑖𝑝𝑖𝑑 − 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑙𝑖𝑞𝑢𝑖𝑑
% 𝑙𝑖𝑝𝑖𝑑 = 𝑥 100%
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑏𝑒𝑎𝑘𝑒𝑟 𝑤𝑖𝑡ℎ 𝑙𝑖𝑝𝑖𝑑
By calculation and through the graph, sunflower seed contain highest percent of lipid
extraction that is as highest 34.48%. This mean sunflower seed have highest contain of lipid than
potato chip and biscuit that contain 24.12% and 12.40% of lipid extraction respectively. Thus, we
should consume more sunflower seed than potato chip and biscuit to provide energy, as we know
lipid have several important roles in the body, provide and store of energy and an energy is needed to
carry out daily activities.
7.0 REFLECTION
We had done the lipid analysis lab. This technique include in extraction of lipids from foods
and also how to calculate the percentage of lipid extraction. From our observation on lipid, we
conclude that lipids was an organic compounds that are very soluble in organic solvents, but it only
sparingly soluble in water. Lipid can dissolve in organic solvent such as in petroleum ether. Through
heated, petroleum ether will lost as a gas. The percent of lipid extraction for the three sample that we
observed, which are a biscuit, a potato chips and a sunflower seed was 12.40%, 24.12% and 34.38%
respectively. Thus, from the result show that the sunflower seeds have the highest contain of lipid
than the others two sample. So, eat a lot of sunflower seed might cause us been obese. Thus, we must
reduce food that contained lipid for a healthy lifestyle.
8.0 REFERENCE
1) Umassedu, 2017, analysis of lipid Retried from
http://people.umass.edu/~mcclemen/581Lipids.html on 6/12/2017.
2) Cyberlipid, 2017, lipid extraction general methodology, retrieved from
http://www.cyberlipid.org/extract/extr0002.htm 0n 7/12/2017.
3) Alex Mijalis, Sep 25, 2015, why are fats soluble in petroleum ether .Retrieved from
https://www.quora.com/Why-are-fats-soluble-in-petroleum-ether on 8/12/2017.
4) Sciencehipermedia, 2017, Extraction and separation of fats and lipids, retrieved from
http://www.aquaculture.ugent.be/Education/coursematerial/online%20courses/ATA/analysis/lip_ex
tr.htm on 9/12/2017.
5) Shakinaz, 2017, lipid briefing .Retrieved from https://padlet.com/shakinaz/SBL1023B on
10/12/2017
