system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: McDonald's unmistakble smell.
gpt
The reason that McDonald's (or any other fast food joint's) restaurants and foods have such a distinctive taste/scent can be summed up in a single word: consistency.

Fast food companies are incredibly fastidious when it comes to their product. The patties have to be of a very specific thickness, weight, fat/lean content, etc. The fries have to be of a fairly uniform girth. Hell, they even measure the dispersal of sesame seeds on each bun.

So they deliver all of that remarkably uniform food to their franchises, who prepare them with identical equipment, much of which is specifically designed to cook specific food items.

So the result is a distinct, brand-wide smell/taste.

Source: A few long conversations for an acquaintance who used to be a meat supplier for small/mid-sized fast food joints, and a pair of friends who worked in procurement and QA for McD's in Europe.