What makes ice cream smooth and creamy?

The challenge
To understand how the microstructure of ice cream changes after temperature abuse.

Background
The microstructure of ice crystals and air bubbles is critical to ice cream’s quality and sensory properties. Ice cream is of course inherently unstable, and temperature increases during transport, storage or even on exit from the customer’s freezer can all play a factor in destroying the microstructure of small ice crystals, leading to recrystallisation and a coarser structure.

Results
Using the X-ray tomography setup of ID19 at low temperature, the microscopic structure of the ice cream became clear, showing the variations in structure of several samples, comparing fresh ice cream with samples that had undergone temperature abuse.

How did the synchrotron help?
The Unilever research was a challenge for the ID19 team, requiring a specialised in situ sample environment and highly-reduced acquisition times. The beam intensity at ID19, the detector system and the low temperature device compatible with high resolution (sample rotation over 180º) led to the high-quality 3D images with a voxel size of just 0.56 micrometres.

Figure 1. Comparison between a) fresh ice-cream and b) “temperature-abused” ice cream clearly showing the larger ice crystals and air bubbles after temperature cycling. Image sizes = 725*725 px2 = 0.41x0.41 mm2.