If you’re watching our little video, you’re among the first to see this very common, naturally occurring, nano-sized structure.
This is a 3D transmission electron tomogram of a single assembly of milk proteins, called a casein micelle.
In our last blog on food structures, we talked about food at the micro scale. A micrometre is one millionth of a metre. This post looks deeper into food and talks about food structures at the nano scale – that’s billionths of a metre! This micelle is around 160 nanometres in diameter. Many viruses are a similar size.
Why is this video important, you ask? It shows us the structure the micelle arranges itself into, and we can see that it forms a cross-linked, interconnected network. Knowing this will help us do things like better understand how the network holds and releases water molecules. This, along with understanding the size variation of micelles, can hopefully help with processing efficiency for manufacturers (like using less energy and water and reducing waste) and product quality of everyday dairy foods like yoghurt, cheese and milk powder.
Tomography is a type of microscopy and it works like a hospital CT scan, except it’s with electrons instead of x-rays. A powerful electron microscope takes a lot of pictures as it moves around the sample and then it is turned into a 3D movie. The black and white at the start of the movie is just the image building.
But milk’s not blue!
We know that casein micelles are a suspension type food structure. We don’t actually know the colour of a single casein micelle, so the scientist who created this image arbitrarily chose to colour it a pretty shade of blue (adding colour helps to bring out the detail). We know of course what the colour is of a population of them together – that’s how milk gets its white!
Nature’s wonder thickener
This tomography video shows a pectin system, which is a gel structure. Pectin forms a strong network giving it properties as a thickener. It’s what sets jams and marmalades and fruit like apples, citrus and plums are packed with it.
Pectin also has a health function because it’s soluble dietary fibre. One benefit of understanding this structure better is to help the manufacturing industry use naturally-derived ingredients to make our food healthier.
We are hosting the Food Structures, Digestion and Health Conference on 24 – 27 October, which will discuss the role of structure in designing foods for nutrition and wellbeing.