Skip to 0 minutes and 11 secondsWe are back in the pilot plant, and we are looking into pasteurisation. So this is a pasteuriser, and it will help us pasteurise apple juice. The idea of pasteurisation is to inactivate pathogens and ensure the safety of the product. So what we do normally is that we have our liquid. In our case, this is apple juice, which we'll fill in the tank. Then this goes into a sort of preheating stage. So the idea is that we want to ensure that the liquid is getting warmed gently before we actually subject it to the temperature of the pasteurisation. In our case, this is 78 degrees Celsius.

Skip to 0 minutes and 45 secondsThe liquid entering into the preheating stage is our first point of monitoring in terms of temperature. Then as the liquid exits that preheating stage, it normally goes into the heat exchanger, where we actually increase the temperature of the liquid to the desired one, so 78 degrees Celsius. And the point of reference for this process is to ensure that we have reached our temperature, so a sensor is always placed at the exit of the heat exchanger to ensure that we have reached the desired temperature. Then the most important thing is this part here, which is a holding tube.

Skip to 1 minute and 17 secondsSo these holding tubes actually hold the liquid for a given amount of time that we want in order to ensure that we have accomplished the lethal effect on the pathogen. This can change according to the dimensions of the instrument, the flow of the liquid, as well as the properties of the liquid itself. Then after this stage, the liquid enters into a cooling stage in which we cool down the liquid so that we can actually have it either in room temperature or chilled temperatures. It then exits through here and enters into aseptic filling stage. This pasteuriser is pilot scale, which means that it is a bit smaller than in the industry.

Skip to 1 minute and 51 secondsIn a usual industrial setting, you would have a series of processes that will end up in the final product being bottled and then it will be dispatched to retailers and consumers. A smaller scale of that pilot product helps us to understand and probably research about different types of microorganisms and how we can inactivate them by testing different times and different temperatures to ensure that, regardless of the liquid or the product, we ensure the safety of it before it gets dispatched to people and consumers. With this instrument, we apply high temperatures for a short time to confer the pasteurisation effect. However, we can also use it for ultra high temperatures.

Skip to 2 minutes and 27 secondsAnd the idea is that that gives us another added benefit of that we can process more liquids, such as juices, milk, smoothies, purées, and beverages. And we have the sterilisation effect at this point, which aims to inactivate even spores for microorganisms. So in that case, in case of sterilisation, we go as high as 140 degrees Celsius, whereas with pasteurisation, we aim at around 70 to 78 degrees Celsius, depending on the product that we process.

Pasteurisation

We continue our exploration of frequently used, traditional food processing techniques with a look at pasteurisation. This is an extremely useful method of eliminating potentially harmful microorganisms and is used for a range of liquid products. The video mentions ‘pathogens’, which are a group of microorganisms that cause disease in humans.

Can you think of items in your weekly shop that are pasteurised? Please share your product lists in the comments section below. The list of commonly pasteurised products is longer that you’d think and includes honey.

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This video is from the free online course:

How is Food Made? Understanding Processed Food

EIT Food