(Laboratory) Expt. 3 - Physical and Chemical Properties of Lipids

Lipid

is a term given for a diverse group of naturally occurring organic compounds which are grouped together

Triacylglycerols

structurally defined as triester of glycerol and 3 fatty acids

solid

Fats are _____ at room temperature

liquid

oils are _____ at room temperature

Steroids

molecules containing a 4-ring nucleus

Miscibility

term used to describe the possibility of forming a solution between a __liquid solute and a liquid solvent__

solubility

the term used to describe the possibility of forming a solution between a __solid solute and a liquid solvent__

Spot test

simplest test for the presence of fats and oils which is based on the fact that fats and oils leave a translucent spot on papers

Acrolein test

used to determine the presence of glycerol. This test is done by heating fats or oils with dehydrating agent

Test for Unsaturation

The test to be used for this is Iodine Number. This is based on the principle that carbon-carbon double bonds undergo addition reaction with halides, such as iodine as illustrated in the reaction below.

Rancidity

is the development of unpleasent smell in fats and oils

hydrolysis

liberates free fatty acids

oxidation

oxidizes carbon-carbon double bonds into volatile aldehydes and ketones

Salkowski’s Test

is a qualitative test for the presence of cholesterol. This is done by adding concentrated sulfuric acid in a cholesterol solution.

Liebermann-Burchard test

is a quantitative test for the presence of cholesterol. It is done by adding acetic anhydride and concentrated sulfuric acid in a cholesterol solution

(mass of beaker + lipid — mass of empty beaker)

formula for mass of lipid extracted

(mass of lipid extracted/mass of food sample x 100)

formula for weight percent of lipid