ICE CREAM CHEM­ISTRY

From gelato to soft serve, what makes our favourite frozen treats?

How It Works - - FRONT PAGE -

Ice cream is made from three main in­gre­di­ents: milk, cream and sugar. How­ever, you need to do more than just mix and freeze them to cre­ate the per­fect dessert. Be­hind this seem­ingly sim­ple sum­mer treat there is some com­pli­cated chem­istry at play.

Ice creams are an ex­am­ple of an emul­sion; a com­bi­na­tion of two liq­uids that would nor­mally not mix to­gether and are dis­persed through­out each other. In ice cream, tiny droplets of fat are dis­persed through the wa­ter. The fat comes from the cream, mostly in the form of triglyc­erides. Dur­ing ice cream pro­duc­tion they are aerosolised and bro­ken down into tiny droplets. Milk pro­teins, which are also added dur­ing the pro­duc­tion process, coat the fat droplets and prevent them from in­ter­act­ing with one an­other. This stops them be­com­ing large droplets again, be­cause the pro­teins stuck to the sur­face of the fat droplet re­pel one an­other.

Many ice creams also con­tain emul­si­fiers, which sur­round the fat droplets and re­place some of the milk pro­teins. This means that the droplets will mix more evenly when they are whipped. As the ice cream is frozen – usu­ally with the help of liq­uid am­mo­nia – it is also aer­ated, and the air be­comes trapped in the dessert by the ar­range­ment of the fat, pro­tein and emul­si­fy­ing in­gre­di­ents.

The fi­nal and ar­guably most im­por­tant in­gre­di­ent is sugar. Not only does this make your ice cream taste great, it also low­ers the freez­ing point of the wa­ter so you don’t end up with chunks of ice in your scoop. Add in some colour­ings and flavour­ings and your ice cream is ready to be en­joyed.

When ice cream melts its molec­u­lar struc­ture breaks down and the air bub­bles es­cape

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.