Fats and Oils

Introduction to Fats and Oils

  • Fats are solid at room temperature, while oils are liquid. This is primarily due to their different triglyceride structures.
  • Both fats and oils are types of lipids, organic compounds that are insoluble in water but soluble in organic solvents.
  • They are important sources of energy, provide insulation and protect vital organs in organisms.

Chemical Structure of Fats and Oils

  • Fats and oils consist of glycerol (an alcohol) and three fatty acids (carboxylic acids).
  • Glycerol is a three-carbon alcohol, each carbon bearing a hydroxyl (-OH) group.
  • Fatty acids are long-chain carboxylic acids, typically containing an even number of carbon atoms and a terminal carboxyl (-COOH) group.

Esterification and Hydrolysis

  • The bond between the glycerol and the fatty acids is an ester link, formed by a condensation reaction.
  • The process of forming an ester link is called esterification, which is a reversible reaction.
  • Hydrolysis is the reverse of esterification, breaking ester links by the addition of water, often catalysed by an acid or base.

Types of Fatty Acids

  • Fatty acids can be classified into saturated and unsaturated types.
  • Saturated fatty acids contain no double bonds between carbon atoms, hence are ‘saturated’ with hydrogen. This mainly contributes to fats being solid at room temperature.
  • Unsaturated fatty acids contain one or more double bonds, resulting in fewer hydrogen atoms and bending of the molecule. This is mostly why oils are liquid at room temperature.

Role of Hydrogenation

  • Hydrogenation is the process of converting unsaturated fats (oils) into saturated fats by addition of hydrogen in the presence of a nickel catalyst.
  • The process is used to increase the shelf life and change the consistency of food products. However, it can result in the formation of trans fats, which have been linked to health problems.

Physical and Chemical Properties

  • The physical properties of fats and oils such as melting point and viscosity are influenced by the length of the fatty acid chains and the degree of unsaturation.
  • Fats and oils can undergo combustion, hydrogenation, and oxidation reactions. Iodine value is a measure of the degree of unsaturation of a fat or oil.

Analytical Techniques

  • Techniques such as chromatography and mass spectrometry are used to analyse the structure and composition of fats and oils.
  • Infrared spectroscopy is used to identify functional groups present in fats and oils, thus providing information about their chemical structures.