When you boil milk you have to be very careful to ensure that it does not boil over and spill on the burner There is no such problem when you boil water Why?
When you boil milk you have to be very careful to ensure that it does not boil over and spill on the burner There is no such problem when you boil water Why?
Unlike water, milk is not a simple liquid.
Milk is a colloid and constituents 85 per cent, water and the rest is distributed among fat, protein, sugar and salts. The boiling point of milk, therefore, is slightly higher than that of water (about half a degree more than 100 degree Celcius). However, before milk is brought to boiling the relatively less dense constituents like the fat and the proteins partially segregate and mostly float up to form the layer of cream. This is a covering layer and does not allow water vapour to pass through it normally.
When milk is boiled in an ordinary vessel, the temperature of the liquid rises, even above the boiling point and a large quantity of water vapour is generated below the cream cover. This makes the cream layer bulge out and causes to spill out. But in the case of water, the vapor bubbles break immediately after forming, and hence the cream does not occur and will not spill over.
Unlike water, milk is not a simple liquid.
Milk is a colloid and constituents 85 per cent, water and the rest is distributed among fat, protein, sugar and salts. The boiling point of milk, therefore, is slightly higher than that of water (about half a degree more than 100 degree Celcius). However, before milk is brought to boiling the relatively less dense constituents like the fat and the proteins partially segregate and mostly float up to form the layer of cream. This is a covering layer and does not allow water vapour to pass through it normally.
When milk is boiled in an ordinary vessel, the temperature of the liquid rises, even above the boiling point and a large quantity of water vapour is generated below the cream cover. This makes the cream layer bulge out and causes to spill out. But in the case of water, the vapor bubbles break immediately after forming, and hence the cream does not occur and will not spill over.
