When should food be thrown out?
“It’s very important to understand the difference between ‘best before’ and ‘use by’ dates,” says Rokx, R&D project coordinator at Storex, a company that specialises in protective atmospheres to extend the shelf life of foods. The first is an indicator of quality, showing when a product is at its peak in terms of taste and texture. Food can often be safe and edible after this date, notes Rokx, and these dates can be stretched a little. The second is related to safety, and is used for perishable goods such as meat and dairy, foods that could be harmful to human health if expired. One of the most useful ways to decide whether to chuck out food is to use your senses, adds Rokx. Our smell and taste are finely tuned detectors of chemicals for food and air, honed over millions of years of evolution. If something is past its best before date but still smells OK, it’s probably still OK to consume. If it looks and smells bad, it’s likely time for it to go. An apple in your fruit bowl can have a bruise or soft spot sliced out, and the rest will still be good. But past a certain point, the rot may have developed to the point that it affects the taste of the whole fruit. (Though hopefully one bad apple won’t spoil the lot). In the EU-funded MAX-FRESH project, Rokx and his colleagues developed the first automated sensor able to detect and warn of volatile gases given off when produce is ripening, fermenting or rotting. The team are working to improve the sensor to calibrate it for each of the roughly 300 gases known to be related to aroma – an important indicator of food quality. The researchers hope they will soon be able to detect between 80 and 100 volatiles. Could such a system exist in our home fridges to guide our decisions? Not in the near future, remarks Rokx, as the sensors are pretty expensive. But he offers a few tips to keep food fresh for longer. Storing products in their correct locations in the fridge can help maintain their freshness – something Rokx adds isn’t always explained clearly enough. Filling a fridge up completely – and all at once – means it will take longer to cool down to the right temperature, which could affect some products. Even leaving the door open for a minute (while making a cup of tea, say) could also have an impact. Planning meals mindfully is a good idea too, to avoid having a lot of half-eaten and increasingly questionable items left at the end of the week. Rokx suggests producers could also put some guidelines on the packaging of certain foods to deduce if things are still edible. “Sometimes you can do a quick test and see if something is still consumable,” he says. For example, eggs that have gone bad will float to the surface in a glass of water – a quick, easy way to avoid ruining breakfast. Click here to find out more about Eugene Rokx’s research: The automated sensor that can sniff out rot in stored food.