“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,” says Associate Professor Jens Risbo, Department of Food Science at the University of Copenhagen, Denmark. He is one of the authors of a recently-published scientific paper in Food Structure, which deals with the new groundbreaking insight into the 3D structure of food.
The researchers used a cream based on vegetable fat for the research. The cream system is a good test material, since it can represent the structures of a large group of food systems, for example cheese, yogurt, ice cream, spreads, but also the more solid chocolate. All the aforementioned products contain liquid water or fat as well as small particles of solid materials, which stick together and form three-dimensional structures – i.e. a network that provides the consistency that we like about cheese, yogurt or chocolate. In cheese and yoghurt the casein particles form the network. In chocolate it is the fat crystals and in ice cream and whipped cream it is the fat globules.
“If you understand the structure, you can change it and obtain exactly the texture you want,” says Jens Risbo.
Electrons with close to speed of light generate intense X-rays
To create a three-dimensional model of the food and convert it into images and video, the scientists have been in Switzerland, where they have used the Swiss Light Source (SLS) synchrotron at the Paul Scherrer Institute. In the synchrotron electrons are accelerated to near speed of light. The synchrotron is used for research in materials science in areas such as biology and chemistry. The method the researchers used is called “Ptychographic X-ray computed tomography.” This is a new method for creating images on the nanometer scale, which also provides a high contrast in biological systems. The synchrotron in Switzerland is one of the leading places in the world in this area, and it was the first time ever that it was used within food science.
“We have been using the tomography principle, also known from an X-ray CT (computed tomography) scanner. The sample of the food system is rotated and moved sideways back and forth with nanometer precision, while we send a very strong and focused X-ray beam through it. 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. The patterns are combined in a powerful computer, which reconstructs a 3D image of the sample. The Swiss scientists of the team have created a device that can move and rotate the sample with ultra-high precision, allowing us to see the small details,” says Research Assistant Mikkel Schou Nielsen, who has recently completed his Ph.D. in tomographic methods applied to food at the Niels Bohr Institute in Copenhagen.