My boss was arguing that this is true and that it's a well known fact amongst culinary professionals that you should never put hot food in the refrigerator (he used to be a baker and had restaurants and such.)
A quick Google search seems to suggest this is a widely held belief that I've never heard of before:
I remember my grandmother would let food cool down on the counter before storing it in the refrigerator. Someone told me that you should never put hot food in the refrigerator as germs/bacteria would multiply. Is this true? Is this an urban myth?
If you put food that's still hot in the fridge, it will raise the temperature of the fridge. Unless you have a huge commercial refrigerator with a strong motor, it will take awhile for the temperature to go back down to the safe level. This means that every single thing that is is the fridge will be at risk for bacterial growth.
My girlfriend and I constantly disagree about this. She was always told, growing up, that you have to wait until recently-cooked food has cooled to room temperature before you can put it in the fridge. If you don't, she says, bacteria will grow on it much more easily and you will get sick.
Has this been investigated properly?