Have you ever employed the 'sniff test' to tell if something is past its use-by-date? Do you prescribe to the 'five-second rule' when food gets dropped? And just how dangerous are burger patties that are still pink in the middle? We put all three to the test with science.
There are many rules in food safety lore, some that have a basis in fact, and some that are purely grounded in convenience. But it’s important to look at the evidence to see which category common rules fall under.
#1 The ‘sniff’ test
Often when a food has spoiled, it will smell bad. This leads many to believe “no stench = OK to eat”. But this isn’t always the case. The microorganisms (bacteria, yeasts and moulds) that spoil food by making it smelly, slimy or mouldy might not give you food poisoning.
But pathogenic (disease-causing) bacteria, such as salmonella, campylobacter, E.coli and listeria, which do make people sick, don’t always cause obvious changes in food when they grow. Sometimes simply being present at low numbers and then consumed is enough to result in illness.
Having said that, this isn’t an invitation to consume obviously spoiled food. Spoilage is a good indicator food has been left too long and “bad” microorganisms, including pathogens, may also have grown.
In order to steer clear of nasty bugs in food, observe “use by” dates, refrigerate foods that need to be kept cold (this slows down the microbes), cook foods properly (this kills the microbes) and prevent contact and cross contamination between ready-to-eat foods such as salads, with raw food such as meat that still needs to be cooked.
#2 The ‘five second’ rule
Whether it’s one, three, five seconds or some other number, we’ve all heard some version of this call when someone has dropped food on the floor. But is it true harmful bacteria need a few seconds to hitch a ride on your dropped slice of pizza?
I saw this open tin of stuffed vine leaves in our office fridge and immediately freaked out. I'd always been told that leaving food in an opened tin risked food poisoning, and I believed that. But then I realised I'd never bothered to question why this rule applied. Time to investigate.