May 28, 2024

I, Science

The science magazine of Imperial College

by Mikayla Hu (6 February 2023)

Take a look at a sun-dried tomato or chili and examine their surface with close attention. Notice anything interesting? Staring at the two you may notice that the wrinkles, which resulted from dehydration, have quite distinctive patterns.  

The wrinkles on the tomatoes forms round dimples, whereas those on chilies form stripe structures on the surface. You may be curious about what has resulted in such a difference, this question does not have an easy answer, but physicists have recently developed a model to explain the theories behind it.

The 3D structural patterns that occur on ageing fruits can be determined by mechanical properties that are, in fact, not dimensional: the stiffness and the curvature of the system. This is according to research published in Physical Review Journals, which discusses specifically toroidal structures, but it’s applying to food like tomatoes and chilies.

The results of applying this model to other fruits showed that a lower stiffness of the core leads to hexagon-shaped dimples on the shell, as in the tomatoes, while a higher stiffness leads to linear patterns, as in the chillies. The curvature, on the other hand, determines where these patterns occur on the surface.

Scientists also claimed that the core-shell model could also shed light on multifunctional surface design to realize specific patterns and structures of interest. But for now, let us stick with the natural origin of this pattern formation. Next time when you cook with a sun-dried fruit, try exploring its morphology for a bit before throwing it into your stew.