When your bottled water tastes like plastic, it may not mean you are swallowing toxic chemicals, but it's far from refreshing. Find out what jars, tins and bottle do to your food
Food packaging has become a new whipping boy. Its excessive use devours our planet's resources, while toxic chemicals lurking within it might be quietly poisoning us. Both of these worries only serve to add to the unpleasantness of being able to taste the damn stuff.
Flavour contamination from packaging is a big, much-studied commercial issue. A company in America called ScentSational Technologies have, for example, devised methods for scenting food packaging, partly as a means of mitigating what is known in the industry as "flavour scalping". This is when some of the food's flavour is lost to the packaging, or when the food absorbs aromas from the packaging.
The taste of plastic
You're in a hot car. You're thirsty as hell and risk a swig from an ancient half-drunk bottle of mineral water. Ugh, it tastes how you would imagine a plastics factory to taste. Dieter Schrenk, professor of toxicology and food technology at the University of Kaiserslautern, says that this assault on the senses is due to: "the four enemies of food packaging: light, oxygen, time and heat". These are the "bad guys", he says, that cause volatile compounds (the quick-to-evaporate chemicals from which we determine smells and flavours) to be released. They can also cause plastics to degrade.
No one should expect bottled water to taste of plastic, unless, perhaps you have left it half-drunk in a hot car for a long, long time. But while a plastic flavour in a fresh bottle would be grounds to complain to the manufacturer, says Schrenk, it might not necessarily indicate the leaching of dangerous chemicals. "In cases where hazardous chemicals may be released from packaging material into food, or even from a plastic toy or new shoes and so on, you cannot smell them. Many of the toxic compounds have no odour." And in any case, he says, the volatile compounds are released in seriously low concentrations. "A very good example is trichloroanisole," he says, "which gives the off flavour of corked wine. The amounts of the compound released into the wine are extremely low, but the receptors in our noses are able to smell these things in extremely low concentrations, which are harmless. But of course the taste of the wine is spoiled."
With chilled foods, the plastic taste is less of an issue, although wrapping foods up in plastic can lead to an unwanted sweaty quality. This is why meat aficionados consider it criminal to remove a steak from vacuum packaging and whack it straight in a hot pan (they would of course eschew vacuum packaging, and unfold the old-fashioned butchers' paper from around their dry-aged cuts well ahead of cooking, unless they were sous-viding it first, in which case, they'd probably vac-pack it again). Wet meat does not brown well (browning being what makes meat delicious). It steams itself, instead.
The taste of metal
Metallic taste, says Schrenk, is very complex: "It doesn't necessarily mean you swallow some metal". Metals act like catalysts and contribute to the degradation of some chemicals in foods, such as lipids. This reaction produces a metallic taste, but it's not the metal you're tasting. "You can easily experience this if you take a few coins into a sweaty hand," says Schrenk. "You detect a metallic aroma but you don't inhale metals, it's just a reaction product between the coins and your skin." However, metals are still a major contributor to off flavours in food, which is why most cans are coated inside with a film of plastic.
The taste of cardboard
In food packaging circles, plain old cardboard and paper are considered a joke. They let flavours in and out without so much as a by your leave. "For example," says Schrenk, "if you store food items next to soap or washing powder, off flavour volatile components may enter the food." Even cornflakes, he points out, are sealed in plastic bags inside the box these days.
The taste of glass
How often do you find yourself bemoaning that horrid glassy taste in your jam? Never. Glass is so very inert, it's just brilliant. It is considered the safest and the best material for preserving flavour. It needs a lid, of course, which will involve metal and/or plastic. And it's heavy and breakable. But you never taste it, which is why I favour used jars over Tupperware-type food containers at home (wild and crazy times over at our house, folks).
Avoiding packaging tastes
You know when it says on a package, "store in a cool, dark place"? That. If you do not expose your foodstuffs to the four nasties: heat, light, oxygen and time, good tastes lay ahead. Heavily dented cans should probably be avoided, to be on the safe side, although Schrenk says the coating in cans is "quite solid and does not crack easily", so the odd dink shouldn't pose a problem. You could, of course, stop buying bottled and canned drinks and refill your own glass bottles instead. And purchase fresh, unpackaged foods daily as required, thus avoiding the need for protective and shelf-life extending wrappings.
Is that even possible in this day and age? What packaging types do you taste the most?
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Food packaged in glass, metal and plastic in a deli. Photograph: Iain Sarjeant/Alamy