A substance called skatole is responsible for the characteristic smell of feces, which in Greek skatos means droppings, feces. These are colorless crystals with a very unpleasant odor, they are found in coal tar, some essential oils, and are formed during the decay of protein substances.
However, in small doses, skatole has a pleasant floral scent and is used in perfumery, in the manufacture of cigarettes, and also as a component of some food essences.
An aggravating circumstance is the considerable stench of the substance. It is clearly recognizable by most tasters when the food contains 0.15 ppm (1ppm = 1 ppm), or 0.00001%. As an indicator, this is comparable to 10 cm in relation to the distance from Moscow to St. Petersburg. In other matters, for fragrant substances this is far from a record, but the value is even very average.
And let it not be scary that this substance can be contained in food, because it is necessarily contained there. You don't even have to add, nature took care of us. The smell of skatole is present in all meat and dairy products. Moreover, everywhere the content of skatole exceeds the threshold of sensitivity to it, in other words, when we eat these products, we distinctly taste / smell this skatole.