Why does milk take more time to cool than tea or coffee?
Tiruchirapalli, Tamil Nadu
Answer 1: Milk takes more time to cool than tea and coffee because of the casein (i.e. the fat present in the milk) that differentiate milk from other liquids. Milk (raw) is a emulsion of casein and water.
If the milk is not heated these fats and water separates which makes the fats to form a giant molecule of fats which makes milk useless.
When the raw milk is heated, initially the water starts heating thenthe fats starts heating. When fats are heated they combine with water molecules to form a saturated liquid.
Milk in tea and coffee is added with powder which contains the chemical caffeine which acts as an emulsifying agent. Emulsifying agent are used to break the fats to smaller components .These small molecules are easily heated as well as cooled compared to higher molecules.
Answer 2: Milk consists of proteins, fats, some water and many nutritional values. Proteins are chains of amino acid molecules connected by peptide bonds.
Milk contains saturated fatty acids i,e. Myristic acid which is 14 carbon atom andhas double bonded molecules. When the milk is heated the water contained in it will get evaporated then bonds present in it become more stronger as it contain more amount of proteins and fats as we know fats are saturated.
In Saturated fatty acids melting point depends on boiling point. So, more we boil the milk more the time to cool it. But when tea/coffee powder are added to the milk the Saturated fats becomes less Saturated then the melting point will be more faster. So, at room temperature milk cools less faster then tea/coffee.
Secunderabad, Andhra Pradesh