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Describe the composition of fat.

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Sarah Richards 13F Essay 11 Describe the composition of fat. (4) Fats and oils, also known as lipids, are formed from glycerol and fatty acids, which combine to create triglycerides. A triglyceride consists of one molecule of glycerol combined with two molecules of fatty acid. The fatty acids are either saturated or unsaturated fat and the proportions and combination of these produce a solid fat or liquid oil. Lipids contain the elements carbon, hydrogen and oxygen. Explain the difference between a saturated fat and a polyunsaturated fat, and describe the working characteristics of each type of fat. (8) All fats contain the elements carbon, hydrogen and oxygen. ...read more.


In relation to plasticity, fats such as soft margarine are useful in all -in -one cake mixtures and for spreading straight from the fridge. Explain the terms hydrolytic and oxidative rancidity. (6) There are several differences between oxidative and hydrolytic rancidity. Oxidative rancidity occurs as a reaction between unsaturated triglycerides and oxygen from the air. However, during hydrolytic rancidity enzymes known as lipases hydrolyse fats, thus breaking them down into glycerol and fatty acids. In oxidative rancidity, oxygen molecules join across the double bond of the triglyceride molecule and form a variety of compounds, which give an unpleasant and rancid taste. This reaction is accelerated by heat, light and traces of metal, such as copper and iron. ...read more.


This is particularly dangerous because not only does it lessen the quality of life, but also obesity can lead to class two diabetes and coronary heart disease. Although all fats and oils have the same calorific value (that 1g = 9Kcals) they vary in quantity of saturated, monounsaturated and polyunsaturated fat. Even though only about 2% of the total energy supplied, as fat is needed to meet the essential fatty acids, normal fat intake is much greater than this. This has caused growing concern, as society gets more obese. In addition to this, although people are starting to realise that saturated fats such as butter are "dangerous" to their health, they are still lacking in general knowledge about other "danger" fats such as fats which have undergone hydrolysis. ...read more.

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