Bake off finalist examines festive favourites under the microscope

Bake off 2023 finalist Josh Smalley got a unique close-up of his festive bakes using a powerful microscope to examine the structure of his Christmas cake and desserts, and see the difference between vegan and non-vegan sweet treats.

Josh, who is postdoctoral researcher in the University of Leicester Institute for Structural and Chemical Biology, joined scientists from the Nanoscale and Microscale Research Centre (nmRC) at the University of Nottingham to create images of vegan and non-vegan meringues to see in detail how the structure differs. They also put Christmas cake slices under the microscope showing the different structures of the fruit cake, marzipan and icing.

The images were created using a technique called Scanning Electron Microscopy (SEM). This is a powerful tool used to visualise the micro- and nano-structures of materials. It works by using a beam of negatively charged particles, called electrons, to scan the surface of the material, creating high-resolution images that show details as small as a few nanometres. One nanometre is approximately one hundred thousand times smaller than the width of a single human hair.

In order to be imaged each bake had to first be covered in gold particles to make it conductive for the electrons.

Josh commented: “I have always had a great fascination in understanding how everything works and what's happening on a molecular scale - none more so than when it comes to baking. Following my appearance on the Great British Bake Off I've been able to combine my passion for chemistry and baking and present to audiences about the science of baking; showcasing how chemistry is fundamental to the flavours and colours of our food, achieving the perfect texture and structure to our bakes/dishes, along with the transformations taking place as we prepare and bake it.”

The images showed that the traditional meringue had a more varied range of sizes of the bubbles (air) but when cream of tartar was added there was more consistency in air bubble size giving a more even rise in the bake. The vegan meringue had a larger air bubble size than either of the two previous ones - suggesting a far foamier, more aerated mix.

The Christmas cake images showed the sugar crystals in the icing, the oily surface of marzipan and the fruit mixture of the cake.

Josh continued: “The images created were incredible. Firstly, it was awesome to be able to see the microstructure of something which I had baked myself. But the level of detail really was breath-taking as it's my first time using a SEM. The imaging went a long way to reaffirming the reason why I add a little acid (e.g., cream of tartar) to my meringue as I've now seen first-hand how it does ensure a more uniform and larger bubble size, hence why the meringue itself is always stiffer and fluffier with this addition. The vegan meringue was the one I was most interested about because as a baker I want to be able to use substitutes in my baking but still generate the same looking and tasting product. The microstructure of the vegan meringue was pleasingly very similar to the normal meringue, but air bubbles slightly larger, which makes sense as it does always feel a little more like a foam when you pipe it out onto baking sheets. All-in-all, a brilliant experience and I have taken so much away from it. Now to decide what to image next...”

Luke Norman, Knowledge Exchange Fellow at the University of Nottingham has been running the ‘Under the Microscope’ initiative for two years to showcase the work of nmRC, items imaged throughout the year have included hedgehog spines, Nottingham lace and pollen and he’s taken the imaging to outreach events across the City. He said: “Working with Josh to look at his bakes was a fantastic way to round off a great year of imaging and outreach. Finding fun and engaging ways to showcase the important research that happens at nmRC is really important in reaching new audiences and engaging them in scientific discovery.”