>>15029093
Cooking doesn't kill all bacteria and they grow back very quickly, and very little starter culture is needed. Plus, most of you use spoons to stir occasionally, which in of themselves will have a bigger flora. Again, leaving the pot with the lid on top, not cooling it down asap (throwing it onto the bacony or whatever) leads to that pot cooling down slowly and remaining at comfy 40-20°C long enought to make it foam, especially if you're cooking onions and meat. You think you prevent pathogens from entering your soup by leaving th lid closed, which is ridiculous. The bacteria want high humidity and warm temperatures. You're incubating them.
The good thing is, you will know when something spoils, as it's mostly bacteria which create lactid acid bacteria. Your soup will fizzle like champaigne and taste like sour. Next time you want to let your pot cool down as quickly as possile, which means opening the lid, to let hot air out, stiring regularly and than putting it into the fridge or if that isn't possible, somewhere cool like a garage. Letting it stay on the heating element, only prolongs the warmth.
t. chef with a background in microbiology