Novel 3D imaging may help curb food wastage

Scientists have for the first time created a 3D image of food on the nanometre scale, an advance that may potentially save the food industry large sums of money by reducing food wastage that occurs because of faulty production.
The method called Ptychographic X-ray computed tomography may help gain detailed knowledge of the structure of complex food systems, researchers said.
"There is still a lot we don't know about the structure of food, but this is a good step on the way to understanding and finding solutions to a number of problems dealing with food consistency, and which cost the food industry a lot of money," said Jens Risbo of the University of Copenhagen in Denmark.

For the study, the researchers used a cream based on vegetable fat. The cream system is a good test material, since it can represent the structures of a large group of food systems, such as yogurt, ice cream, spreads, but also the more solid chocolate.
All these products contain liquid water or fat as well as small particles of solid materials, which stick together and form 3D structures.
"If you understand the structure, you can change it and obtain exactly the texture you want," said Risbo.

To create a 3D model of the food and convert it into images and video, the scientists used the Swiss Light Source (SLS) synchrotron at the Paul Scherrer Institute in Switzerland.

Ptychographic X-ray computed tomography is a method for creating images on the nanometre scale, which also provides a high contrast in biological systems.
"The sample of the food system is rotated and moved sideways back and forth with nanometre precision, while we send a very strong and focused X-ray beam through it," said Mikkel Schou Nielsen, former PhD student at the Niels Bohr Institute in Copenhagen.
"The X-rays are deflected by colliding with electrons in the food, and we shoot a lot of pictures of the patterns that the defleted X-rays form," Nielsen said.
"The patterns are combined in a powerful computer, which reconstructs a 3D image of the sample," he said.

The reconstructed 3D image can be described as a 3D table of numbers describing the electron density (the number of electrons per volume) through the entire sample.
The various food components, such as water and fat, have different densities and hence different electron density.
One may now use the electron density to identify the various food components and study their location and structure.
"If we eventually come to understand the structure of chocolate, we can change it and obtain exactly the consistency that we want," said Risbo.
"It is certainly a possibility that tomographic methods could be developed so we would be able to understand the mysteries of chocolate," he said.

The study was published in the journal Food Structure.