Fat Determination


Lipids are a family of naturally occurring compounds grouped together on the basis of their relative insolubility in water and solubility in nonpolar solvents. These are naturally occurring molecules that can be isolated from cells and tissues by extraction using nonpolar organic solvents.There are two classes of

i) those with ester linkages that can be hydrolysed, for example, fats and waxes

ii) those without ester linkages and so cannot be hydrolysed, for example, cholesterol and steroids.

Fats and oils are triacylglycerols. They are triesters of glycerol (propane-1,2,3-triol) with three long chain carboxylic acids. Reaction with aqueous sodium hydroxide yields glycerol and the three fatty acids. Fatty acids are usually unbranched and contain an even number of carbon atoms, usually from 12 to 20. If there are any double bonds, they tend to have cis geometry. Fats containing one double bond are monounsaturated and those with more than one double bond are polyunsaturated.Saturated fats have a uniform shape that allows them to pack together in a crystal lattice. Unsaturated fats have double bonds that introduces kinks into the hydrocarbon chain making crystal formation more difficult. This is why saturated fats have higher melting points and are solids at room temperature compared to unsaturated fats that tend to be liquids (oils).The most abundant lipid in olive oil is glyceryl trioleate, a triester formed from glycerol and oleic acid, a mono-unsaturated fatty acid with a cis double bond in the middle of the C18 chain

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