Summer coolant - physics to the rescue!

Abstract

To mark the start of National Ice Cream week, Dr Peter Barham of Bristol University took part in the second in a series of public lecture, exhibition and reception evenings for the general public organized by the Institute. His talk was entitled: `Frozen assets: from baked alaska to banking' and provided an entertaining look at why a knowledge of the laws of thermodynamics can be vital in the manufacture of high quality ice cream. There were also comparisons with the movement of money in the money markets! Ice cream is an interesting mixture of three physical states - solid, liquid and gas - which are present as solid ice and fat crystals, a thick sugary solution and air bubbles. Dr Barham demonstrated the importance of producing crystals small enough to be unnoticeable when you bite into your ice cream and a sugar solution thick enough to bind it all together but soft enough to allow the mixture to be scooped! Getting the right balance for all these properties depends on physics, including the temperature at which the mixture is frozen, how much it is stirred and the amount of solid impurities present. Figure 1. A young guest enjoys her ice cream concoction at The Institute of Physics on Thursday 23 July. Figure 2. A young entrant in the ice cream sundae-making competition puts the final touches to her entry under the watchful eyes of Johnny Ball and two of the Ice Cream Alliance demonstrators. At the end of the lecture, Dr Barham made ice cream in a matter of minutes for the audience to try. Later, those present had a chance to create their own ice cream from a range of bizarre flavourings and to make their own ice cream sundaes. The evening was supported by the Ice Cream Alliance, the trade association for the UK ice cream industry.