PROJECT 4: LIPID

Title: Saponification of triglycerides

Introduction

            Fatty acids are straight chain monocarboxylic acids with hydrocarbon chains of 4-36 carbons. Fatty acids can be either saturated or unsaturated. In saturated fatty acids, all carbon-carbon bonds are single bonds while all carbon-carbon bonds in unsaturated fatty acids has at least one double bonds.

            The simplest lipids constructed from fatty acids are triglycerides. Triglycerides are composed of three fatty acids each in ester linkage with a single glycerol. Liquid triglycerides are oils while solid triglycerides are fats.

            Saponification is the hydrolysis of triglycerides under basic condition to produce glycerol and salt of fatty acid. The salt of fatty acid is called soap. In saponification, the ester linkage is broken down to produce glycerol and soap.

            Saponification number can be used as an indicator of fatty acid chain length in triglyceride. The value is a measurement of milligram of KOH required to complete hydrolysis of one gram of fat or oil. The long chain of fatty acids have low saponification value as they have a relatively fewer number of carboxylic functional groups per unit mass of fat. 

Material

Triglyceride samples (palm oil, corn oil, sunflower oil, butter, margarine), solvent (1:1 ethanol/ether), 0.5M KOH, 0.5M HCl, phenolphthalein

Procedure

1. Hydrolysis for sample (sunflower oil)

2. Hydrolysis for control

Result

 

 

Discussion:

On refluxing with alkali, triacylglycerol (fatty acid esters) are hydrolysed to give glycerol and potassium salts of fatty acids (soap), such process id known as saponification. The saponification value is the number of milligrams of KOH required to neutralize the fatty acids resulting from the complete hydrolysis of 1 g of fat. The saponification values gives an indication of the nature of the fatty acids constituent of fat and thus, depends on the average molecular weight of the fatty acids constituent of fat. The greater the molecular weight (the longer the carbon chain), the smaller the number of fatty acids is liberated per gram of fat hydrolysed and therefore, the smaller the saponification number and vice versa.

In this experiment, there are few sample that have been tested to determined its saponification value, which are butter, sunflower, corn oil, margarine and palm oil. All these samples have different saponification number after being tested. Based on this experiment, corn oil and palm oil have the lowest saponification number which is 28.06. This number indicates that both corn oil and palm oil have a long fatty acid chain length in triglycerides. While, the saponification number for sun flower, margarine, and butter is 33.67, 84.17, and 98.19 respectively. Butter have the highest saponification number in this experiment, this means fatty acid in butter lower than fatty acid in other sample. 

Conclusion: 
Based on this experiment, we have studied saponification of triglycerides. 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. The process is called saponification or soap formation, since the potassium salts of fatty acids are in fact. While, the saponification number used to indicates the fatty acid length in triglycerides.

Reflection:

1. TING MEE PING (D20141067055)

From the experiment, I have observed that sunflower oil has the highest saponification number. Saponification number indicates the of fatty acid chain length in triglyceride. The long chain of fatty acids have low saponification value as they have a relatively fewer number of carboxylic functional groups per unit mass of fat.

  

2. LENDRA NALAT ( D20141067021)

In this experiment, I have learned about saponification of triglyceride and how to determine its saponification number. Besides that, I also learned to always be careful especially when handling chemical substances which is corrosive. 

3. CHRIS ROXA ANGELLA SUPAIN (D20141067094)

From this experiment that we had conduct, I have learned about saponification. I was able to make our own soap with our own creativity by using some ingredients. It was my very first experience to make a soap and I found it was very interesting mini project. Beside that I also learned that sunflower have the highest saponification number due to the shortest length of fatty acid chain in triglyceride compare to the other oils. 

Reference:
Mary K. Campbell, Shawn O. Farrell (2015) Biochemistry.8th Ed. Cengage Learning

Garret, R.H., & Grisham, C.M. (2013). Biochemistry (3^rd ed.). USA: University of Virginia

Nelson, L.D and Cox, M.M. (2012) Principles in Biochemistry (6^th Ed). Lehninger. W.H. Freeman. 




 

  

The making of soap

Soap