• They are insoluble in water and soluble in
• Pure triacylglycerols are tasteless,
odourless, colorless and neutral reaction.
• They have lesser specific gravity (density)
than water and therefore float in water.
• Through fats are insoluble in water, they can
be broken down into minute droplets and
dispersed in water. This is called
• They contain hydrophilic coloidal particles
such as proteins, carbohydrates and
phospholipids which act as stabilizing agents.
• Fat is hydrolysed to yield three
molecules of fatty acid and one
molecule of glycerol. The hydrolysis of
fat is effected by alkali and enzyme.
• The process of alkali hydrolysis is
• The alkali salt of fatty acid
resulting from saponification is
• Hydrolysis of triacylglycerol may
be accomplished enzymatically
through the action of lipases.
• Development of disagreeable odour and
taste in fat or oil upon storage is called
rancidity. Rancidity reactions may be due
to hydrolysis of ester bonds (hydrolytic
rancidity) or due to oxidation of
unsaturated fatty acids (odative rancidity).
• The partal hydrolysis of the triacyglycerol to mono
and diacylglycerol is called Hydroytic rancidity. The
hydrolysis is hastened by the presence of moisture,
warmth and lipases present in fats or air. In fats like
butter which contains a high percentage of volatile
fatty acids, hydrolytic rancidity produces disagreeable
odour and taste due to the liberation of the volatile
butyric acid. Butter becomes rancid more easily in
• The unsaturated fatty acids are
oxidised at the double bonds to form
peroxides, which then decompose to
form aldehydes and acids of
objectionable odour and taste