system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the milk in my coffee not spoil after hours in my thermos?
gpt
The spoiling of milk products is due to the growth of certain strains of microbacteria that cause fermentation byproducts. It takes a reasonable amount of time with the ideal conditions (room temperatures, proper oxygen..etc) to grow these bacteria. WIthin a few hours these bacteria may grow in minimal amount of numbers, although not enough to spoil milk in a (most likely still warm) thermos.