Why is it necessary to use salt in ice cream
Why is it necessary to use salt in
ice cream
Almost everyone likes ice cream. This food is sweet, soft and
cold. Ice cream is a frozen cream mixture. In large-scale industries, special
freezers are used to freeze ice cream dough. In small-scale industries, for
example ice-puter sellers and ice-kegs, ice cream dough is frozen not with
freezer, but with ice cubes mixed with kitchen salt (NaCl). In this simple way,
salt functions to lower the temperature of ice cubes so that it is cold enough
to freeze ice cream dough. Without the addition of salt, the temperature of ice
cubes will not be cold enough to freeze the ice cream mixture.
Why adding salt can reduce the temperature of ice cubes?
Actually many blog articles have discussed this, but most are
only general and do not answer the root of the question. It is only said that
adding salt will reduce the freezing point (melting point) of water, but the
temperature reduction mechanism is not explained.
I will describe a clue to explain this mechanism. In a 4-season
country, sometimes snow accumulates too thick to cover the road. Local
residents usually sprinkle salt powder on the snow to melt. So, salt has the
ability to melt (melt) ice. How does salt do it?
When salt is sprinkled on ice, salt particles interfere with
the stability of the bonding of water particles that are in the solid phase
(ice). Salt particles break into the ice particle bond so that they break the
bonds. As a result, ice particles that are on the surface can separate from the
trapping force of the ice particles which are on the side and below. The ice
particles that manage to break away then move to the liquid phase.
Ice has an average temperature below 0o C. In the case of the
addition of this salt, ice melts without the addition of heat, so that the
water formed from the fusion also has temperatures below 0o C. This is why it
is said that adding salt can reduce the melting point of water , because ice
can melt below its normal melting point (0o C).
So, salt particles are triggers for melting ice. On the other
hand, as we know, ice fusion requires energy (absorb heat). Now, because heat
is not supplied from the outside, the ice absorbs heat from itself, so the
temperature of the ice drops further. The ice whose temperature has become very
cold will then absorb a lot of heat from the ice cream mixture, so the ice
cream mixture can freeze.
This phenomenon is what helps street vendors to make icecream without a freezer. Cheap.