SCHOOL OF FOOD SCIENCE & NUTRITION
NT20903 FOOD CHEMISTRY AND BIOCHEMISTRY
Determination of free fatty acid(FFA) and iodine value (IV)in oil
LECTURER NAME : MOHD NAZRI BIN ABDUL RAHMAN
LAB SESSION : 3 OCTOBER 2011 (GROUP 4, MONDAY)
Title: Determination of free fatty acid (FFA) in oil and determination of iodine value (IV) in oil Introduction
Acid value or free fatty acid content is an important characteristic commonly used in quality control of fat and oil. Fats and oils are one of the large variety and important sources in the world. It contains acidity which is the result of the degree of breakdown of the triacylglycerols by a chemical reaction known as hydrolysis or lipolysis generally. Fresh and healthy oils or fats may also have significant amounts of acidity. This fact is usually due to the errors during the biosynthesis or extraction of oils from fruits. Oils and fats that produced from low quality fruit or through a careless process will consequences in breakdown of the triacylglycerides into fatty acid. These fatty acids are called free fatty acids (FFA). Free fatty acids can used as an immediate source of energy by many organs and can be converted by the liver into ketone bodies. Free fatty acid form during the breakdown of lipid by hydrolysis and oxidation. Thus, free fatty acid is hydrolyses from dietary lipid for absorption or utilize for lipid synthesize. Free fatty acid play important role in food system and our body system also too .Free fatty acid is same with unsaturated fatty acid, which is giving help to our body .
To verify the quality of fats and oils, acid value or free fatty acid can be used. Acid value is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance. Acid value is normally calculated in order to determine the amount of free fatty acids. This method is applicable to all normal fat and oil. Titration with sodium hydroxide is use to determine acid value by to neutralize free fatty acid in 1g of fat. The percentage of free fatty acid is expressed in the term of acidity. While for the free fatty acid, it is calculated by a method which the molecular weight of a particular fat is used in it. The molecular weight is vary depends on different type of fat.
Type of fat or oil| Expressed as| Molecular weight (g/mol)| Coconut, palm oil kernel and any resulting fractions| Lauric acid| 200| Palm oil and any resulting fractions| Palmitic acid| 256| Other liquid oil| Oleic acid| 282|
The process of breakdown of lipid by hydrolysis and oxidation generated free fatty acid. However, acid value is not possible used to differentiate between the free fatty acid formed during the process of hydrolysis and oxidation. But it still can widely used to determine the quality of fat and oil in food system. This is an appropriate method to all fat and oil. Oil or fat that made carefully from freshly or unspoiled fruits generally will have lower acid value under 0.5% of free fatty acid. But for extra virgin olive oil will have less than 0.8% of free fatty acid. Based on the titration result, we can conclude the relationship between acid value and free fatty acid in the oil. The higher result of acid value we get, we can determine how higher value of free fatty acid in the oil. Therefore, the test will carry out with carefully to avoid mistaken appear in the test. However, sometime it is hard to use acid value to differentiate between the free fatty acid formed during the hydrolysis process and oxidation process.
Halogenation is one of the addition reaction. Fat or oil generally consists of double bonds between carbon atoms which inclined to undergo addition reactions. Halogen such as chlorine, bromine, iodine monochloride and iodine monobromide will across the double-bonded carbon atoms in the fat or oil during halogenation. As a result,...