Question: how long would it take for a roast dinner to rot

Rachel Edwards-Stuart answered on 11 Mar 2013:

Wow, that’s certainly not something I have ever thought about! Bacteria cause both spoilage (ie foods to go rotten) as well as food poisoning (which makes you sick). Bacteria need food to grow, so will grow in foods with lots of sugar and protein, like a roast dinner. I think if you left your roast dinner out, it would actually take a week or two before the spoilage bacteria were actually able to break down the food in significant numbers and start to rot. (Remember that bacterial numbers grow by doubling, so it starts as one, which becomes two, which becomes four, which become eight etc, so they can grow to quite big numbers in a short amount of time and start decaying food very quickly – think of how a piece of fruit that starts slightly bruised can go very rotten almost overnight!). It would obviously rot quicker in a warmer climate, because the bacteria would multiply quicker, and all the processes causing the deterioration would happen more rapidly. It would also be quite a disgusting experiment to do, and I can think of other things to do with a good roast!