Food Science & Food History – Pasteurization

One of my favourite hobbies, as you might have discovered by now, is figuring out the science behind cooking and baking. Trying out recipes, explaining why they worked out, or why they didn’t… Nothing more fun than that to be honest. You’ll find a lot of posts on my website trying to do just that, either through an ultimate cookie series or by making nice infographics explaining one specific topic in more detail.

There is however another topic that I find very interesting, it’s food history. More specifically, food history of the past 150 years or so. When you link the development of food with social changes it becomes mightily interesting!

This hit me once when I read a book about the history of hot dogs, hamburgers and pizza. As well as a great book linking social developments of the past 5 or 6 decades with developments in food (industry), unfortunately I cannot find this book back…

So, I thought I’d also start writing posts about changes in food (industry) and here’s my first one! What’s great, I can link a lot of sciency things to history as well!

History of pasteurization

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All examples of dairy products that have undergone heat treatment to extend the shelf life.

Recently I posted a new one-page infographic, explaining the science behind milk. One of the topics described on this infographic is heat treatment of milk to preserve the milk longer: pasteurization. Since that’s been one of the main inventions for food, I decided to zoom into this invention for my first history post.

Louis Pasteur was born in 1822 and was to become a micobiologist and chemist who would do a lot of world changing discoveries. He developed vaccines and found out that micro-organisms cause fermentation, improving understanding for processes such as the yeast rising process of dough.

The process that actually got his name though, is the pasteurization process. At the time of Louis Pasteur it was known that micro-organisms exist, they’d been seen with a microscope. However, scientists still commonly believed in ‘spontaneous generation’, thus that micro-organisms could just appear. Louis Pasteur was the first one to prove that this is not the case. He proved that some sort of germ should be present.

This discovery made him come up with the pasteurization process (as well as other processes) around 1864. He figured that if he would be able to kill micro-organisms and then be able to prevent new ones from entering, a product could be protected from spoilage.

Up to that moment in time a lot of children (and adults) were killed by drinking raw milk which contained pathogens, micro-organisms that cause disease. The pasteurization of milk was able to drastically reduce this number.

In the years after the invention is has been refined to the process it is today. With current analysis techniques we are able to determine very accurately for how long and how warm the milk has to be heated to kill off all disease-causing bacteria. These settings for milk are heating to 65°C for 30 minutes or 75°C for 10 seconds.

As you might know, pasteurized milk still has to be stored in the fridge, why is this? Well, the described heat treatment does kill all disease causing micro-organisms, however, not all spoilage micro-organisms. So, to prevent these from growing too fast, milk has to be stored cool.

 

Sources:

Harold McGee, On Food & Cooking; Lebensmittelmikrobiologie, J. Krämer, 5. Auflage, Brittanica, Wikipedia, ChemHeritage

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