How do they pasteurise an egg without it coagulating?

There’s an article in a magazine called ‘the scientist’ that describes a machine that does it. (Not sure that isn’t somewhat promotional). But the gist of it is they head the egg internally for a specific length of time to a controlled temperature 62 C (145 F) to 72 C (161 F). The time will vary based on the mass of the egg.

One can reasonably assume that the energy required for pasteurization must be less than the energy required to begin (significantly) cooking the egg.

Also, based on my very scant knowledge of proteins, I believe that proteins tighten up and coagulate when they experience a quick rise in temperature, as opposed to a slow and gentle one.

Maybe this information on egg curdling can shed some more light. Also, I’m seeing online that it is generally considered safe to eat something that has been heated to between 140–160 degrees. It seems like an egg could flirt with 140 briefly and not become scrambled.

@Grisson :s/head/heat/ (What happened to my ability to edit!?)

Thanks for both your responses. So Grisson by “internally heating” the egg are we talking some kind of microwave?

@lexicon That wasn’t clear from the article (nor the georgiaeggs web page I also found), though that’s how I would interpret ‘internally heating’, too.

It is interesting. I was expecting that the answer would be irradiation (non-microwave) of some sort. But I guess that’s not ‘pasteurization’ technically and apparently there is some resistance to irradiation from the consumer community.

The pasteurization regime is a combination of time and temperature, so that the higher the temperature that is used, the less time is required. Fortunately, the main pathogen that you’re trying to kill in eggs is Salmonella, which is not very heat-resistant. They can be killed in 60 seconds at 63C. Most guidelines specify more than that though, typically 4 minutes at 64C.

That would be enough heat to curdle egg white alone, but whole beaten eggs will just barely tolerate this without curdling.