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Now you will focus on the methods to determine the fatty acid profile of a food (in this case margarine). At the end of this part you will finalize your database.

The fatty acid profile of the margarine was determined by using GLC.

Principle:

GLC is a separation technique that can be used to separate fatty acids in a sample. All forms of chromatography separation techniques involve a stationary phase, often hold in some type of tube called “column” and a mobile phase, a gas (such as helium or hydrogen) flowing through the column. In GLC, the components in the sample are first volatilized at a high temperature and then passed on a column which is held in an oven. The stationary phase is a high boiling point liquid coated on support material. How fast a particular compound of the sample travels through the column depends on the affinity of the compound for the stationary phase. Different components travel with a different speed. This depends on the (chemical) structure of the component. Play the animation to learn more about GLC.

Before GLC analysis it is necessary to prepare non-polar volatile derivatives of fatty acids (most often methyl esters). There are several chemical procedures to prepare methyl esters. Acylated lipids are transformed by a transesterification reaction by which the glycerol is displaced by another alcohol (in case of methyl esters this is methanol). This transesterification can be acid catalyzed or base catalyzed.