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Homogenisation

Video demonstrating the homogenisation process and what it is used for.
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Food processing is a core part of food sciences that aims to preserve food products for longer. One of the processes that we have in terms of food processing is the homogenisation step. Homogenisation is an important part, especially for the sector of dairy. Milk is an oil-water emulsion, and normally when it comes to milk processing, we would separate the cream from the milk, then we would pasteurise these two streams independently. And then we would do a process which is called standardisation. So the idea is that we produce different milk products with different fat content.
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However, fat globules at this point are large, so we need to ensure that we decrease the particle size so that they can be stable for longer, this being part of the dispersion phase in the serum. That is why we use the homogenisation step as a process that aims to reduce the fat globules by allowing the milk to flow with high pressure into a homogenisation valve that will break these fat globules into much smaller ones. Of course, this process can also be extended into other products, such as solids. And there are other ways of homogenisation, like colloidal mill or extrusion. When it comes to these facilities, –so, this is part of an extended process, looking into a semi-continuous ice cream.
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So after the homogenisation step, we’ll move into ageing and freezing. When it comes to milk production after the homogenisation step, we would move into packaging and distribution of milk. In terms of visual appearance of a homogenised milk, if you were to compare a non-homogenised and a homogenised one, you wouldn’t be able to see the differences with the naked eye. However, if you had the chance to put a drop under the microscope and compare the two milks, you will see that in the unprocessed milk, you will see big, larger fat globules floating about in the serum, whereas in the homogenised one, this will be far smaller.
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Nowadays, due to modern life, we need to ensure that milk stays homogenised and it’s extended so that we can reach the consumers at any part of the globe. That is why we need the homogenisation step to ensure that this happens for an extended time period. So in terms of setting in the pilot plant, we will have an individual unit operation, as in the case of the homogeniser. However, on a commercial scale, this will be part of a continuous line that will follow on from separation and pasteurisation, and then will lead to packaging. Of course, the mechanisms and the objective are the same. The thing that changes is the volumes, which will be much larger.

This video is filmed in the University of Reading Pilot Plant, part of the Department of Food and Nutritional Sciences. It’s purpose is to provide students with experience of industrial processes and also to enable pilot processes to be tested for research purposes.

This film featured milk being homogenised but the process applies to other products too, for example, mayonnaise. Can you think of food items you commonly buy that are homogenised? Does it say so on the packaging? Please share your findings with other Learners in the comments.

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How Food is Made. Understanding Food Processing Technologies

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