Question: Can you make food not expired by adding chemicals or substances

Simone Sturniolo answered on 25 Jun 2013:

Yes. That’s what food preservatives are for. After all, the very first food preservative in history was simply salt! Salt was used to dry out certain foods, since it absorbs its water. Without water, they would become harder to attack for moulds and other microorganisms, which need moisture of some kind to prosper. The absence of water also stops some chemical reactions.
In general, food preservatives are either some kind of antibiotic – to kill bacteria and moulds that would attack the food – or some kind of antioxidant – a substance that “sacrifices itself” by oxidizing in place of the food, allowing it to last longer! The problem with preservatives is that, of course, they need to be non-toxic, or they would kind of miss the point… for example, adding a bit of hydrochloric acid to fruit pulp will make it last for months even in open air, but it will also make it poisonous, so it’s not a good preservative! In general, some people prefers to eat foods without too many preservatives, because they feel like they are more natural. Personally I don’t think there’s something wrong with the idea, but I’m for using technology and science in the least amount necessary and not abusing it, so if one food works well without preservatives, I’d say to just leave it alone ;).