Vegetable Oils Determining Degree Of Unsaturation And Viscosity Biology Essay

Oil is an integral part of everyone’s life. Life without oil is not possible, especially in cooking. But there is a limit to which how much oil can be used for the purpose of cooking. The health factors have to be considered. There are different types of oil that are used for cooking and eating purposes. But how many of them are actually safe for health? How many of them do not cause any health problems like high cholesterol etc which in turn leads to diseases like heart attacks?

This topic is definitely worthy for investigation because a lot can be found out by determining the iodine number of different oils. For example, the degree of unsaturation is the main thing that can be found out by performing the experiment of Iodine Value. From the degree of unsaturation, we can determine the boiling points of the oils and their effect on the human body. Though my experiment is only for four oils, namely, mustard oil, olive oil, coconut oil and canola oil, there is great scope for investigation even in these oils. The main purpose of this investigation is to establish the relationship between the degree of unsaturation in the oil and the viscosity of the oil

Vegetable or “Cooking” oil is used on an everyday basis. Vegetable oil is purified fat of plant origin which is liquid at room temperature.There are many different kinds of vegetable oils, some of them are: Olive oil, Sunflower oil, Soybean oil, Sesame oil, Coconut oil, Peanut oil, Corn oil etc.

Fats and oils are esters of triglycerols and fatty acids. When an oil is unsaturated, it means that the fatty acids consist of a long chain hydrocarbon that have carbon-carbon double bonds.

The degree of unsaturation can be determined by finding out the amount of mass that is used to overcome the carbon-carbon double bonds.The amount of iodine that reacts is used to find the iodine number of the oil and this is used to indicate the degree of unsaturation in the oil. The higher the iodine number the greater the unsaturation.

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Unsaturated oils are less stable than saturated oils. They keep less well than the saturated oils. This is because the carbon carbon double bond in the unsaturated oils react with the oxygen in the air. This may lead to discolouration to the surface of the oil, decrease in the nutrient oil and they also lead to rancidity. They are more prone to hydrogenation and to hydrolysis.

Oils are very important to our body, they provide energy because they contain proportionately less oxygen than carbohydrates and they release more energy when they are oxidised.They also provide the structural components of the cell membrane. They also help in the production of steroid hormones like progesterone and testosterone.

Unsaturated oils are very harmful to health. They damage the immune system, cause hormonal imbalances and many other problems. They pose a major health risk. Unsaturated oils get rancid when exposed to air; that is called oxidation, Free radicals are produced in the process. This process is accelerated at higher temperatures. The free radicals produced in this method react with parts of cells, such as molecules of DNA and protein and may become attached to those molecules, causing abnormalities of structure and function.

The greater the degree of unsaturation of the oil, the better it is for the body. This is because, as mentioned above, the greater the degree of unsaturation the lower the melting point. The average body temperature of the human body is around 98.8.F. Any oil below this temperature is extremely good for the body. This is because the oil won’t linger in the stomach for a very long time, because if it stays in the stomach for a very long time, then it can make the body sick. Also, oils below this temperature helps in dissolving the fat that is already present in the body instead of further accumulating the amount of fat in the body. These oils do not clog up the arteries and they do not become hostile plaques.

If the oil has less degree of unsaturation or is saturated, then it has a higher melting point, this is because the Vander Waal forces are stronger when compared to the oils that have a greater degree of unsaturation. This would require more energy to overcome the intermolecular forces causing a higher melting point. Now, since the oil will have to burn at a higher temperature, the body temperature has to rise to above the average body temperature to that specific temperature. If it does not reach to that particular temperature for the oil to burn, it can cause indigestion and clogged arteries. They help raise a person’s high density lipoproteins (HDL). HDL carries cholesterol from the blood back to the liver. The liver then breaks down the cholesterol so that it can be eliminated from the body. This helps the excess cholesterol from being deposited in the arteries.

Word Count: 572

EXPERIMENT A- DETERMINING THE IODINE VALUE OF THE OILS

Design

2.1.1 Aim: Finding the iodine number to determine the degree of unsaturation of various different vegetable oils

Iodine Number: it is the measure of the degree of the unsaturation in oils and fats. It is expressed in terms of centigrams of iodine absorbed per gram of sample( percentage by weight of iodine absorbed)

2.1.2 Apparatus:

Iodine Flasks, 250 ml

Micro Beaker, I ml

Burette, 50 ml

Beakers, 250 ml

2.1.3 Chemicals Required:

De ionized Water

Carbon Tetrachloride

Iodine monochloride(Wij’s solution)

Potassium Iodide solution

Starch Solution

Aqueous Thiosulphate standard solution

2.1.4 Oils required:

Olive Oil

Mustard Oil

Coconut Oil

Canola Oil

2.1.5 Procedure:

One 250 ml iodine flask was labeled “BLANK” and the other iodine flask was labeled “SAMPLE”

A sample of oil was collected in a 50 ml beaker of known weight and was weighed in an analytical weighing balance in order to obtain the weight of the oil to 4 decimal places

Subsequently, 20 ml of Carbon Tetrachloride was added to the beaker, stirred and this solution was transferred to an Iodine Flask.

5 ml of Wij’s Solution was transferred to the iodine flask using a microbeaker

The Iodine flask was covered with an airtight lid and was kept away in the dark for 45 minutes

After 45 minutes, 10 ml of Potassium Iodide solution was poured into the lid of the Iodine Flask

The lid was slowly raised allowing a minimum air gap to prevent any iodine vapours formed as a result of the previous reactions, thus allowing the Potassium Iodide to drip slowly into the iodine flask

100 ml of water was added to the flask in a similar way and stirred so that the excess iodine was dissolved

The solution was then titrated with Na2­S2O3 solution and when it turned to a straw color, approximately 5ml of starch solution was added which made the solution turn into a blue-black solution

The titration was resumed drop by drop until the solution turned colorless.

The volume of Na2­S2O3 was noted( both in the beginning of the titration and at the end of the titration)

The above procedure was carried out without the oil to obtain the “BLANK” value

The experiment was repeated thrice with the same oil

The same procedure was carried out with another sample of oil

Calculations

Formula for the calculation for the Iodine Value of any oil

Where:

B – Volume of Na2­S2O3 required for the “BLANK” sample

S – Volume of Na2­S2O3 required by the “SAMPLE” sample

S – Normality of the Thiosulphate Solution (N)

W – Mass of the oil taken (g)

2.2 DATA COLLECTION

DATA COLLECTION

OLIVE OIL

Initial Volume (ml)±0.05 ml

Final Volume (ml)±0.05 ml

Reading 1

0

13.9

Reading 2

0

14.3

Reading 3

0

14.1

Volume of the “BLANK” sample = 28.6 ml

Mass of the oil = 0.2407 gm

MUSTARD OIL

Initial Volume (ml) ±0.05 ml

Final Volume (ml) ±0.05 ml

Reading 1

0

9.4

Reading 2

0

9.1

Reading 3

0

8.9

Volume of the “BLANK” sample = 28.6 ml

Mass of the oil: 0.2527 gm

COCONUT OIL

Initial Volume (ml) ±0.05 ml

Final Volume (ml) ±0.05 ml

Reading 1

0

26.5

Reading 2

0

27.3

Reading 3

0

26.8

Volume of the “BLANK” sample = 28.6 ml

Mass of the oil: 0.2808 gm

CANOLA OIL

Initial Volume (ml) ±0.05 ml

Final Volume (ml) ±0.05 ml

Reading 1

0

6.0

Reading 2

0

5.2

Reading 3

0

5.5

Volume of the “BLANK”sample = 28.6 ml

Mass of the oil = 0.2771 gm

2.3 DATA PROCESSING

OLIVE OIL

Average Values

Initial Volume= = 0 ml

Final Volume = = 14.1 ml

Calculation of the Iodine Value

=78.98

MUSTARD OIL

Average Values

Initial Volume = = 0ml

Final Volume = = 9.1

Calculation of the Iodine Value:

= 101.2

COCONUT OIL

Average Values

Initial Volume = = 0ml

Final Volume = = 26.9ml

Calculation of the Iodine Value:

= 9.937

CANOLA OIL

Average Values

Initial Volume = = 0ml

Final Volume = = 5.6ml

Calculation of the Iodine Value:

= 108.8

Error Propagation

Blank Value= 28.6 ml

Error in the “BLANK”: ±0.05 ml

OLIVE OIL:

Value of the “SAMPLE”: 14.1ml

Error in “SAMPLE” : ±0.05 ml

(BLANIK-SAMPLE) = (28.6-14.1) = 14.5 ml

Error in (BLANK- SAMPLE) = ±(0.05+0.05)= ±0.1 ml

Percentage error in (BLANK – SAMPLE) = 0.69%

Percentage error in mass = 0.02%

Therefore % error in Iodine Value: 0.02+0.69 = 0.71 %

Value of Iodine Number = 78.98

Error in Iodine Number = ±0.56

Iodine Number of Olive Oil = 78.98±0.56

MUSTARD OIL

Value of the “SAMPLE”: 9.1ml

Error in “SAMPLE” : ±0.05 ml

(BLANK-SAMPLE) = (28.6-9.1) = 19.5 ml

Error in (BLANK- SAMPLE) = ±(0.05+0.05)= ±0.1 ml

Percentage error in (BLANK – SAMPLE) = 0.51%

Percentage error in mass = 0.02%

Therefore % error in Iodine Value: 0.02+0.51 = 0.53 %

Value of Iodine Number = 101.2

Error in Iodine Number = ±0.54

Iodine Number of Mustard Oil = 101.2±0.54

COCONUT OIL

Value of the “SAMPLE”: 26.9

Error in “SAMPLE” : ±0.05 ml

(Blank-Sample) = (28.6-26.9) = 1.7 ml

Error in (Blank- Sample) = ±(0.05+0.05)= ±0.1 ml

Percentage error in (Blank – Sample) = 5.8%

Percentage error in mass = 0.02%

Therefore % error in Iodine Value: 0.02+5.8 = 5.82 %

Value of Iodine Number = 9.937

Error in Iodine Number = ±0.59

Iodine Number of Olive Oil = 9.937±0.59

CANOLA OIL

Value of the “SAMPLE”: 5.6ml

Error in “SAMPLE” : ±0.05 ml

(Blank-Sample) = (28.6-5.6) = 23 ml

Error in (Blank- Sample) = ±(0.05+0.05)= ±0.1 ml

Percentage error in (Blank – Sample) = 0.43%

Percentage error in mass = 0.02%

Therefore % error in Iodine Value: 0.02+0.43 = 0.45 %

Value of Iodine Number = 108.8

Error in Iodine Number = ±0.49

Iodine Number of Olive Oil = 108.8±0.49

EXPERIMENT B- DETERMINING -THE VISCOSITY OF THE VEGETABLE OILS

3.1 Design

3.1.1 Hypothesis: To determine the viscosity of the following oils:

Olive Oil

Canola Oil

Mustard Oil

Coconut oil

3.1.2 Apparatus required:

Viscometer

25ml density bottle

Weighing balance

Pipette

3.1.3 Chemicals Required:

Olive Oil- 25 ml

Mustard Oil- 25 ml

Canola Oil- 25 ml

Coconut oil- 25ml

Distilled water- 25 ml

3.2 Procedure:

Part A: Determination of the Density

The oils were added up to the brim of a 25 ml density bottle of a known weight. The bottle was covered using a lid. And the excess oil was dipped off from the side of the lids. The density bottle was then cleaned. The bottle and the oil together were weighed in order to get the mass of the oil that is going to be used in the process of the experiment

With the help of this calculated weight and a predetermined volume of 25 ml , the density of the oil could be calculated.

The above process was carried out for all the oils and the water as well

Part B: Determination of time taken in order to flow down a viscometer

A Viscometer consists of a U-Tube with 2 reservoirs. 100 ml of the oil was added to the opening as indicated

The oil was then pipetted up on the other side until the lower meniscus reached the level marked as A.

It was held at this point by using a finger which covered the opening.

As soon as the finger was released the oil flowed down and the at the same time a timer was started.

The oil flowed through the reservoir and as soon as the lower meniscus reached the level marked at B, the timer was stopped and the time was noted.

The above procedure was carried out for all the other oils and was carried out for water as well

With the help of the above data, the viscosity of the oil , relative to the viscosity of the water could be calculated.

3.3 Data Collection and Processing

Density of the Samples:

Name of Sample

Mass of 25ml gravity bottle(± 0.00005 g)

Mass of 25 ml density bottle + sample (± 0.00005g)

Mass of the Sample (±0.0005 g)

Density of the sample( Mass of the sample/25)

Olive Oil

17.2358 g

40.2675

23.0317

0.9213

Canola Oil

17.2358 g

40.2872

23.0514

0.9221

Mustard Oil

17.2358 g

40.0860

22.8502

0.9140

Coconut Oil

17.2358 g

40.2733

23.0375

0.9215

Water

17.2358 g

42.3569

25.1211

1.0048

Time Taken

Name of the Sample

Time Taken(± 0.5 sec)

Olive Oil

8659

Canola Oil

6144

Mustard Oil

7628

Coconut Oil

9952

Water

151

Calculations

Formula for the calculation of the relative velocity

ÅŠ1 = D1 Ã- t1

—— ————–

ÅŠ2 D2 Ã- t2

Where,

Where:

ÅŠ1 = Viscosity of Oil

ÅŠ2 = Viscosity of water

Clearly,

ÅŠ1 = Relative Viscosity of Oil with respect to water

———

ÅŠ2

D1 = Density of oil

D2 = Density of water

t1 = Time required for the oil to flow between 2 marked points on the viscometer

t2 = Time required for water to flow between 2 marked points on the viscometer

3.4 CALCULATIONS

From the above observations we can find the viscosity of the oils.

Olive Oil = [0.9213 ± (2 Ã- 10-6)] Ã- (8659 ± 0.5) = 52.27 ± 0.2

———————————————-

[1.0048 ± (2 Ã- 10-6)] Ã- (151 ± 0.5)

Canola Oil = [0.9221 ± (2 Ã- 10-6)] Ã- (6144 ± 0.5) = 37.33 ± 0.2

———————————————

[1.0048 ± (2 Ã- 10-6)] Ã- (151 ± 0.5)

Mustard Oil = [0.9140 ± (2 Ã- 10-6)] Ã- (7628 ± 0.5) = 45.95 ± 0.2

———————————————–

[1.0048 ± (2 Ã- 10-6)] Ã- (151 ± 0.5)

Coconut Oil = [0.9215 ± (2 Ã- 10-6)] Ã- (9952 ± 0.5) = 60.44 ± 0.2

———————————————-

[1.0048 ± (2 Ã- 10-6)] Ã- (151 ± 0.5)

ANALYSIS

From the above graphs, we see that there is an inverse relationship shared between the degree of unsaturation and the value of the viscosity

Unsaturated oils are those that have carbon carbon double bonds because it lacks hydrogen atoms. Poly unsaturated oils are those that contain more than one carbon double bond. They are also called the polyunsaturated fatty acids or PUFA’s and sometimes, they are also known as “Essential fatty acids”

The degree of unsaturation can be found out by finding out the amount of mass that is used to overcome the carbon-carbon double bonds.The amount of iodine that reacts is used to find the iodine number of the oil and this is used to indicate the degree of unsaturation in the oil.

A carbon double bond consists of one σ bond and one Ï€ bond. σ bonds are formed by the “end on” interaction of the electrons in a s-orbital. When they react they produce a bond in which the electron density is at its greatest on the internuclear axis ( imaginary line joining the nuclei) and is symmetric about it.

Ï€ bond is formed by the “side on” interaction of the electrons of the p-orbitals at right angles to the internuclear axis. This bond has low electron density on the inter nuclear axis . The electron density for this type of bond is at the highest on the sides opposite to the internuclear axis.

The presence of the double bond in the hydrocarbon chain makes the short. And hence there is greater number of electrons causing greater amount of repulsive forces. This is called the Bayer’s strain. The more the number of double bonds the greater the strain and shorter the length of the hydrocarbon. These types of hydrocarbon chain undergo addition reactions faster when compared to those that are longer with less number of double bonds. When they undergo addition reaction they get relived of the stress and the strain causing the length of the hydrocarbon to expand. Hence, the greater mass of Iodine use, the greater the number of carbon double bonds and greater the Iodine number and greater the degree of unsaturation.

Therefore, greater the iodine number greater the degree of unsaturation

The carbon in the double bond is sp2 hybridized. Hence the shape is trigonal planar and the molecule comes into one plane. Therefore, the molecules in a double bonded carbon are spaced out. When the carbon bond is saturated, that is, having only single bonds, the bonds are sp3 hybridized. The shape therefore is tetrahedral and hence molecules become spread in two planes. As a result, the molecules become more tightly packed, thus becoming denser. Therefore, lesser the amount of double bonds, the more tightly it will be packed when it becomes saturated and hence it will become more denser. This brings out a relationship between the iodine value, the degree of unsaturation and the viscosity. Greater the iodine value, greater the degree of unsaturation and lower the value of the viscosity.

Greater the degree of unsaturation, lower the melting point. This is because in unsaturated oils there are carbon-carbon double bonds. The presence of these double bonds makes the hydrocarbon chain less straight. This weakens the strength of the Van Der Waal’s forces because there is less contact between the chains. Therefore, greater the degree of unsaturation, lower the melting point.

Also, unsaturated oils are less stable than those that are saturated. Therefore, greater the degree of unsaturation, the less stable it is.

CONCLUSION

From the above experiment and analysis, we observe various number of things. Greater the Iodine value of the oil, greater the degree of unsaturation and lower the viscosity. Using this analysis, we can say that Canola Oil has the highest iodine value, that is, and the least Viscosity value, that is . This means that Canola Oil is the safest to cook and use because it provides a lot of health benefits when compared to the sample of the other oils. Mustard oil, which has an iodine value of and Viscosity value of is the comes second in the four oils that have been used for the experiment. Olive oil, that has an iodine value of and a viscosity value of is not recommended to use because out of the four oils that are were used for the experiment this falls under the third category. Coconut oil is very hazardous for the health because its iodine value is and the viscosity value is. It is recommended not to use coconut oil for cooking purposes.

Sources of Error

Error might have occurred when transferring the oil from one beaker to another. This might have lead to minor errors occurring in the process of the experiment

The analytical balance did measure the mass of the oil to an accuracy of four significant figures, but there were few disturbance like noise and the shaking of the table around the analytical balance that made the digit in the balance to waver between one number to another.

There might be some ICl (Iodine Monochloride) left behind when it was transferred from the beaker to the Iodine Flask.

After the one hour in the dark, KI was to be added to the iodine flask by opening the lid slowly and making the KI to drip slowly into the flask. During this short period where the lid of the flask was opened, there might have been chances where the iodine vapors could have escaped from the reaction in the Iodine Flask causing errors in the experiment.

During the process of titration, there are chances that there was excess amount of Sodium Thiosulphate was added for the color to turn colorless. This might have caused the wrong reading being taken which in turn can lead to the wrong calculation that can increase the difference between the original Iodine value and experimentally calculated Iodine Value

While measuring the amount of starch solutions, Wij’s solution etc, to be added in the process of the experiment, there are chances of parallax errors that could have caused errors in the process of the experiment

There are chances that the apparatus had some tiny unwanted particles that might have been mixed with the other chemicals causing errors in the experiment

While measuring the volume of the sodium thiosulphate used for the experiment from the burette, there are chances that there was a tiny difference between the reading that was recorded and the actual reading.

The solution f Potassium Iodide was prepared in the lab by diluting the KI powder into water. Therefore, there might have been an error in the diluting the Potassium Iodide like for example, adding extra Potassium Iodide powder or adding extra amount of water.

In some of the apparatus, there were readings that were not very clear. This might have caused errors in the experiment.

For the experiment to determine the Viscosity of the oils, the experiment had to be carried out in similar atmospheric conditions. There could have been variations in the chemistry lab hence leading to errors in the experiment.

Evaluation:

To reduce the weighing error, the sample should be weighed repeatedly. This will reduce the random errors caused because of the weighing. This will also give an accurate mass that will reduce the errors in the experiment.

While transferring chemicals, care should be taken so as to avoid the chemicals from spilling

Repeated measurements could have been conducted while measuring the “BLANK” value and the “SAMPLE” value. This would have reduced the random as well as systematic errors that are caused by incorrect readings and unclear readings in the apparatus.

The apparatus used in the lab for the process of experimentation should be of good quality so as to minimize the errors and increase the accuracy in the experiment.