Question: Why does food go off and what bit of dna in the fruit make it go off

Grant Campbell answered on 12 Mar 2013:

Food goes off mostly because we are at war! We are at war with other things that want to eat our food! Micro-organisms (bacteria, moulds, fungi) and insects also need food, and they want to eat the same things we want to eat. On their side they have enormous numbers – trillions and trillions – and great flexibility. On our side we have cleverness and technology, which we use to kill off bugs and/or to slow them down, so that the food stays edible (by us) for long enough to feed us when we need it. (For example, most of our food is grown in the summer, but we need to eat throughout the winter, so we need to preserve it.)

The main tools our cleverness has given us for preserving food are:

Temperature – heat to kill bugs (sterilisation and pasteurisation, as well as ordinary cooking), cold to slow them down (chilling and freezing).
Removing access to water – by drying or concentrating or by using high concentrations of salt or sugar.
Chemicals that stop bugs growing – alcohol and acids are the main ones.
Radiation (very occasionally, for things like spices)

I don’t know about the dna in fruit, sorry!