That sour taste may lead to riskier behaviour Sam Diephuis/Getty

Most of us are reluctant to take chances when it comes to out-of-date food. Yet rather than put us off, a mouthful of sour milk might increase our appetite for risk-taking in future.

Marianna Obrist at the University of Sussex, UK, and colleagues have investigated how the five principal flavours affect risk-taking. Seventy participants in the UK were given a drink to sip which contained plain water, or water flavoured to be salty, sweet, sour, bitter or umami – the savoury flavour offered by MSG.

Immediately afterwards, the volunteers played a video game, the aim of which was to inflate a balloon by clicking on it. Each click delivered a monetary reward, but the pot was wiped out if the balloon burst.


Sweet and umami flavours were associated with more conservative strategies, with fewer balloons bursting overall. Those given a sour drink were the riskiest gamblers, clicking 40 per cent more than the sweet drinkers.

Influencing the brain

The experiment was repeated with 71 participants in Vietnam, where the umami flavour is more popular, but still got the same result, suggesting this might be a universal effect.

Obrist says she doesn’t know why sour flavours might do this, but we know that our sense of taste has been linked to a range of cognitive effects – not only guiding food choice, but also predicting personality traits, influencing social behaviour, working memory and even our relationship with alcohol.

Obrist and her colleague Chi Thanh Vi say their results hint that flavours could provide a new way to help manage mental health issues – for example, sour chewing gum might encourage people with anxiety disorders to be more adventurous.

Journal reference: Scientific Reports, DOI: 10.1038/s41598-018-26164-3

Read more: Bitter tastes make you more judgemental