Got Milk?

I know I said that I wouldn't get involved in entrapment, but sometimes I think Susan needs some inspiration and I'm happy for history to judge me as her muse as she achieves immortality. To that end I've been stupid-fishing. The other day as I was making my coffee, I started pondering the subject of long-life milk and what they do to extend milk's famously ephemeral existence. Some of you may already know why and think I'm stupid for not knowing*. Perhaps you can start a website mocking me? Anyway, I thought I would put my question to the oracle, and as i was bringing the tea and coffee in I asked if anyone knew. Susan did.

Apparently the reason long-life milk is so, is because...

"it's to do with the carton"

Brilliant. Of Course it is. Please explain, Susan

"well, you know how cereal is kept fresh in the box, it's the same with milk"

What Susan is saying is that the carton being sealed is what stops it from going off. I don't know whether she thinks that other milk cartons have holes in. Sometimes I can't hope to understand, and all I can do is document.

*for those who also don't know- long-life milk is, as I'm sure you're aware, also known as UHT milk, UHT standing for Ultra-High Temperature. They heat the milk up to a very high temperature over a short period of time (1-2 seconds) thus killing some of the thermoresistant spores that pasteurisation doesn't. It's then placed in sterilised cartons. So I guess it is to do with the carton. Shit.