Measuring the fatty acid percentage of the reused sunflower oil after numerous times of potato frying and determining the effects of it on human health.

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ASLAN Özge Cemre D129077

CHEMISTRY EXTENDED ESSAY

“Measuring the fatty acid percentage of the reused sunflower oil after numerous times of potato frying and determining the effects of it on human health.”

Özge Cemre Aslan

D1129077

Session: May 2010

Supervisor: Serenay Tarhan Güler

TED Ankara College Foundation High School

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ASLAN Özge Cemre D129077

TABLE OF CONTENTS Abstract Introduction…………………………………………………………………………………….1

Research Question……………………………………………………………………2

Background Information………………………………………………………………3

Chemistry of Fatty Acids and Oils

Information on Effects of Fatty Acids and Oils

Experiment

Materials…………………………………………………………………………………6

Preparation of KOH and phenolphthalein…………………………………………… 7

Method……………………………………………………………………………………8

Preparing the sunflower oil……………………………………………………………9

Determining the percentage of free fatty acids in the sunflower oil by acid-base titration…………………………………………………………………………………………10

Data Collection and Processing………..……………………………………………………..10

Calculations to find the free fatty acid percentage………..………………………………..13

Conclusion and Evaluation……………………………………………………………………16

Conclusion of the investigation……………………………………………………………….16

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ASLAN Özge Cemre D129077

Evaluation of the investigation………………………………………………………..17

Appendix

Data Processing

Error Propagation

Bibliography

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ASLAN Özge Cemre D129077

Change in Fatty Acid Percentage of Oil After Frying Potatoes

Measuring the fatty acid percentage of the reused sunflower oil after numerous times of potato frying.

Introduction:

In the 21st   century that we are living in, most of the people changed their habit of nutrients. Fast foods became popular and take the place of main meals because of the faster life which does not let people eat their meals at home. We became addictive to those foods which do not really feed us. The faster the people started to eat, the faster the restaurants became to work. So fast food restaurants found new ways to get used to this  hectic life-style. Many companies started to use trans-fats in their foods because they’re  easy to use, inexpensive to produce and last a long time. These kinds of fats give foods a  desirable  taste and texture. So they can make more money with less spending  and  also  be  delicious. Trans-fats  (or  trans  fatty  acids)  are  created  in  an industrial process that adds hydrogen to liquid vegetable oils to make them more solid. As  they  do  not  exist  naturally,  trans-fats  are  difficult  to  metabolize  and  so  they accumulate in the fatty tissues of the body. They also cause an increase in the levels of LDL (bad) cholesterol and a decrease in the levels of HDL (good) cholesterol, which can lead  to  atherosclerosis  (narrowing  of  the  arteries)  and  a  resultant  increase  in  the probability of strokes and  heart problems. LDL is low-density lipoprotein; HDL is high- density lipoprotein. Their density is determined by the amount of proteins present in the molecule. As HDLs have a  much  higher percentage of proteins  as  LDLs, they can prevent the build-up of cholesterol in the arteries. The lower percentage of lipids in HDLs

means these can absorb more cholesterol and hence carry it from the arteries.

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ASLAN Özge Cemre D129077

Many  restaurants  and  fast-food  outlets  use  trans-fats  to  deep-fry  foods because oils with trans fats can also be used many times in commercial fryers. Trans means that H-atoms are on the opposite side of the carbon chain.  The polarity of the molecules determines the forces of attraction between the molecules in the liquid state. Polar  molecules  are  attracted  by  the  opposite  charge  effect  (the  positive  end  of  a molecule  is  attracted  to  the  negative  end  of  another  molecule). As  a  result  trans- unsaturated  oils  have high melting points. And the higher melting point increases the number of frying that can be made by using trans-oils. So it can be seen that another property  apart  from  taste  and  cheapness  is  being  reusable.  As  a  contrast,  poly- unsaturated oils (containing more than one C=C) such as sunflower oil and corn oil have lower melting points.

When you fry your potatoes in deep-fryer with normal sunflower oil many times, you may think that this oil can make no harm because it is not a trans-fat. But is it totally safe to fry the  potatoes with the same oil even if this oil does not have a trans fat structure? Thus  my  research  question  is:  Can  lots  of  fries  increase  the  free  fatty  acid percentage in the vegetable oil and harm us or this increase is a benefit?

These questions are not so far from our lives. My life is also hectic between the roads of my school and my house. Every day, at lunch I eat my meals at school. And my menu mostly has potato fries in it because of the limited time I have for lunch and it is faster to eat fried potatoes. So when I started to read some news at the newspaper

about the oils that companies use in frying, I started to question my meals and wanted to learn the reality about the potato frying which I eat everyday with my thousands of

friends at school. Because of this, I chose free fatty acid percentage in frying oil as an

extended essay subject and my aim in this experiment was to “prove the harmful effects

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ASLAN Özge Cemre D129077

of reused vegetable oil in potato frying and to find out the consequences of aggregate in numbers of frying, on free fatty acid percentage of the oil used”.

A fatty acid is a long hydrocarbon chain carboxylic acid which has an acid group at one end and a methyl group at the other end. Hydrolysis is the splitting of a covalent bond by reaction with water. Fatty acids are produced by the hydrolysis of the ester linkages which are the bonding between fatty acids and glycerol that characterizes true fats,  in  a fat or biological oil (both of which are triglycerides), with the removal of glycerol.  A  triglyceride is formed from one molecule of glycerol (propan-1,2,3-triol, CH2(OH)CH(OH)CH2OH) and three fatty aliphatic acids (R-COOH).

Structures are shown in the figure below:

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1         Taken from <  ‐milk‐facts.com/images/GlycerolTrigly.gif>

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ASLAN Özge Cemre D129077

Figure  1:   Structures   of  glycerol  and  triglyceride- saturated.

The human body is able to synthesize most of the fatty acids it requires, saturated or unsaturated.

Saturated fat is the fat which has the hydrocarbon chain without double bonds present between carbon atoms. This kind of oils is mostly animal fat based oils like butter which can  stay solid at room temperature. The oil that we experimented is unsaturated fatty acids.  That fatty acids have one or more double bonds ("-CH=CH-") formed by the removal of hydrogen atoms. These include vegetable oils and are found to be liquids at around room  temperature because of their low melting points. Here is an example of

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fatty acid structure.2

Figure 2: Structure of a fatty acid

Fatty acids can be bound or attached to other molecules, such as in triglycerides or phospholipids. When they are not attached to other molecules, they are known as "free"

fatty acids.

H2  C        OH HC        OH

H2 C O

HC

HO         C         R

O

O         C        R O

O         C        R O

Figure  3:  Structures  of  glycerol,  free  fatty acid and triacylglycerol which the free fatty

acid had binded.

H2  C        OH

H2  C         O         C         R

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