The phrase "rotten food" refers to food that has gone bad or spoiled. It is no longer safe to eat and usually has a bad smell and taste. Full definition
During the house cleaning he finds a container of severely rotten food. (nerdlocker.com)
A more likely explanation for the Minorcan's addiction to Datil peppers was that the Florida heat caused food to spoil faster, and adding spice to their dishes would mask the taste of rotten food. (fieryfoodscentral.com)
In my case during my first run of the game, I ate rotten food found in a house and my character began vomiting to the point of my food and drink stats plummeting to zero and blacking out soon after as I tried to return to the only water source I had found. (thelatenightsession.com)