An artificial tongue that can work out exactly how spicy something is has been developed by researchers.
In good news for those who can’t handle the heat, a simple transparent square can quickly detect whether a curry is mild or likely to blow your head off.
A prototype was able to detect capsaicin – the compound that provides the ‘spice’ in chili peppers – at levels comparable to human detection.
It could also identify other compounds that produce stinging, tingling or burning sensations, often found in the likes of black pepper and garlic.
‘Our flexible artificial tongue holds tremendous potential in spicy sensation estimation for portable taste–monitoring devices,’ lead author Weijun Deng, from the Shanghai Institute of Technology, said.
The team utilised a familiar trick – using milk to neutralise spiciness – when designing the tongue.
For example, when someone has a spicy curry and follows it with a spoonful of mint yoghurt, the spicy capsaicin compounds are bound by casein proteins in milk, nullifying them.
They used this phenomenon to inspire their prototype – with promising results.
This transparent square acts like an artificial tongue, reacting to capsaicin and similar pungent compounds in proportion to a food’s spiciness
Comparison of the artificial tongue with human taste testers, showing results were closely matched
The researchers created a thin film using an electrochemical gel material and added casein in the form of skimmed milk powder.
They discovered that when spicy capsaicin compounds were added to the ‘tongue’, the electrical current running through it decreased.
Initial tests showed that the material responded to spice concentrations ranging from below human detection to beyond levels perceived as painful.
It also successfully detected pungent–flavoured compounds found in common hot sauce ingredients such as ginger, horseradish, garlic and onion.
The scientists then tested their prototype on eight pepper types and eight spicy foods, including a range of hot sauces.
A panel of taste testers rated the spiciness of the same items. Analysis showed results from the artificial tongue and the tasting panel matched well.
The researchers said their device could be used to quickly test a food’s spiciness level – without putting your taste buds at risk.
‘The gel–based artificial tongue in this study is simple to prepare with low cost, providing a convenient way to detect the concentration of various pungent compounds,’ they wrote in the journal ACS Sensors.
Peppers and related products can range in spice levels from ‘mild’ to ‘dangerous’, the researchers said (left). Taste testers also evaluated their pain level when trying different spicy foods as part of the study (right)
Currently, measuring flavour compounds in foods requires trained taste testers and complex laboratory methods.
Other scientists are also developing artificial tongues which can measure sweet and umami tastes.
The team said their design could one day be transformed into a portable taste–monitoring device, used by people with a real aversion to spice.
It also has potential for use in movable humanoid robots or patients with sensory impairments such as ageusia – a loss of the sense of taste – they said.
