Why does food go off! – Hydrogen Zone

Question: Why does food go off!
- Keywords:
  food
Asked by ryankelly to Aggelos, Andrew, Eileen, Naomi, Shane on 13 Nov 2012.
- Andrew Jackson answered on 13 Nov 2012:
  
  hi
  
  food goes off because microbes like bacteria or fungus tend to like eating our food too and they grow on it, and in the process digest it and leave it all nasty. One of the greatest discoveries of medicine was made this way – Alexander Fleming discovered antibiotics by accident one day when he found peniciliin growing on some food for the microbes he was growing was left out on a bench! The agar food (which is made from seaweed extract and is used to feed and grow bacteria) he left out had little circles of bacteria in it with places where they wouldnt grow. In the centre of these circles he found a fungus that makes the antibiotic penicillin that was poisoning the nearby bacteria staphlococcus. In doing so he made a discovery that would save millions of lives of people and is still a very common first choice antibiotic for many people (except me… im one of the few that are allergic to it so i have to take something else!)
  
  you can read more about Alexander Fleming, his discovery, penicillin and how antibiotics work here http://en.wikipedia.org/wiki/Alexander_Fleming#Accidental_discovery
  
  cheers
  andrew
- Aggelos Zacharopoulos answered on 13 Nov 2012:
  
  @ryankelly
  food goes off when micro-organisms commonly called “bacteria” start feeding on it, growing and multiplying. The bacteria themshelves can then enter our body and cause infections if we eat the food or the bacterial “waste” can be poisonous to humans.
  
  One way to pevent that is by pasteurising the food once it is produced. We basically heat it to around 80 C for a few minutes which kills off any existing bacteria (pasteurisation) and then seal it to prevent any new bacteria getting into it.
- Eileen Diskin answered on 14 Nov 2012:
  
  Like Andrew and Aggelos say, food goes off because of the bacteria that feed on it grow and multiply – which are pretty gross, making our food go funny colours and smells.
  
  But not all food goes off, especially when the scientists who help make certain foods put preservatives into it – so it lasts forever. I saw an experiment online where a woman had her McDonalds hamburger in a tupperware for TWELVE YEARS and it still didn’t get moldy!!!! (Apparently it just got a bit dry and had a little bit of a smell – but I still wouldn’t want to eat it!) I think thats maybe even grosser than the food that DOES go off…it makes you wonder what sorts of things they’re putting into that meat to make it last so long!
- Naomi Elster answered on 14 Nov 2012:
  
  Food goes off when other things – microbes – get to eat it before we do! Bread mould is caused by a fungus which feeds on the bread and then turns it into its home, spreading out to make a green carpet along the crust of our sandwich! (Actually, I learnt once that bread mould is harmless to us if we eat it, but I’ve never tried to myself).
  
  There are lots of ways to prevent food from going off. Bacteria and fungi can’t survive in lots of salt, which is why some foods, like olives, come in brine, and why a lot of meats are salted or spiced. Heat kills off microbes as well, which is why we cook our food. Milk and fruit juices can’t be boiled or the quality diminishes, which led to Louis Pasteur developing a special technique where they would be heated slowly to 80 degrees. This means that bacteria are killed but the flavour stays.

Question: Why does food go off!

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