My mom was telling me that if I put the unfinished bowl of milk and cereal back to the fridge, the saliva that has been stuck to the spoon gets passed to the milk. The saliva in milk will make milk go bad faster than if there were no saliva inside. Is that true? If so, how comes? It would be great if there are scientific evidences or references to back it up.
I have found a Quora post having some people saying that it will make the food go bad faster. I was not able to find any other references