system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If a Snack Pack pudding is dairy, how does it have a shelf life of 12+ month?

I checked my snack pack today and noticed the ‘sell by’ date. To say the least I was surprised when I saw it was almost a year away. 

Please ELI5 how a dairy product can have such a long shelf life!
gpt
Back in the 1800s a guy named Louis Pasteur figured out that food spoiled due to the actions of microscopic living creatures called bacteria. These living creatures didn't spontaneously appear out of nowhere but reproduced from other living bacteria in the environment.

He had the idea that if a container could be sealed and all the living creatures within killed, such as with the careful application of heat, then the food within wouldn't spoil. This process is called "pasteurization" and is in use today on dairy products of all kinds.