Food structure and image analysis
Alix Cornish, Senior Scientist
Many foods and food materials have a non–uniform structure and composition. They may contain bubbles, emulsions, multiple components such as fruit pieces in yoghurt, structures such as marbling fat in meat, or gradients of fat, water or salt.
As well as measurements of average composition, aspects of the structure, appearance and distribution of components are also important. There are several techniques available to study these as Alix Cornish explains.
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Food structure is important because it relates directly to texture and the consumer perception of food. It's very important for things like crispiness and creaminess - they're directly related to the food structure.
During new product development manufacturers often want to make a particular texture. In order to do this they need to create a particular structure. Also, during reformulation trials, for example, if they're trying to reduce the fat or sugar in a product they're going to want to create a new product that has the same texture as the previous products. In order to do this they need to match the structures.
Food structure analysis allows you to make measurements of the internal structure of food without destroying the sample. This can be useful for quantifying food structure, and changes over time, and this can be backed up by measurements from sensory panels.
We do see problems relating to food structure, a lot of these problems relate to changes in shelf-life over time. For example, for chocolate mousses they might start off with quite a high volume and over time we lose the bubble structure and therefore the volume decreases over time. Other problems we see relate to moisture migration, particularly in products of multiple components, particularly a high moisture component and a very dry component next to it. We see moisture migration from the high moisture component into the dry component, often this loses its crunchiness and goes soggy.
We are actively researching food structure - we've got an ongoing project looking at the structure of bread and another project about to start looking at the structure in cake. Both of these projects look at how the ingredients we use and the processing conditions we use affect the structure of the cake or the bread.
X-ray micro-CT can also be used to look at food packaging and is particularly helpful when there's a problem with a food packaging so a defect somewhere. X-ray micro CT can look inside without having to destroy the packaging sample look at where the defect is and how that has affected the product inside it.