Hardening

Hardening is the last stage in making ice cream. When the mix becomes thick and difficult to stir, only about half of its water has frozen into ice crystals. Agitation is then stopped, and the ice cream is finished with a period of quiescent freezing, during which another 40% of its water migrates onto existing ice crystals, leaving the various solid components less lubricated. If hardening is slow, some ice crystals take up more water than others and coarsen the texture. Hardening can be accelerated by dividing the newly frozen ice cream into several small containers whose greater surface area will release heat faster than one large container.