Recently I’ve read an article: “The science of meringue” written by Fine Dining Lovers. They have many articles about food on their website, including this one. This one precisely is about what happens during churning proteins with sugar and why it's happening.

I have always found cooking fascinating. That's because we can change the whole dish by just making a few changes in the recipe. For example, whipping cream for too we can produce butter or add more or less of specific ingredients can change the whole structure of meal. That is why I think that this article is so absorbing. They are explaining what chemical changes are taking place during making meringue and what to do to make perfect meringue.

Sources:

https://www.finedininglovers.com/article/science-meringue?fbclid=IwAR1DJO9NsDYeKfHYmsWwixRpwQhTU96iExSKmpqI8ggbSE-7xYsGw-2zjKk