A sweet treat

A sweet treat

From Unexpected Elements by BBC World Service

February 27, 2026 · 51 min

About this episode

This episode explores the science of chocolate, the search for dark matter, and the influence of taste.

A dip in global cocoa prices got the Unexpected Elements team wondering about chocolate science. First, we look at how the microbial communities in cocoa beans fine tune the taste of chocolate. Also, could table sugar help us detect the missing bits of the universe? We look at how three elements in sugar were used in the hunt for dark matter. We’re then joined by Professor of Experimental Psychology Charles Spence, who explains the myriad ways that taste can be influenced – including the shape and name of chocolate, and even the music we listen to as we eat it. Plus, we hear about the rediscovery of a moth in South Africa that was lost to science for 150 years. And finally, why we cry when we chop onions and the insects that pollinate the cocoa tree. That’s all on this week’s Unexpected Elements. Presenter: Marnie Chesterton, with Candice Bailey and Sandy Ong Producers: Sophie Ormiston, with Lucy Davies, Tim Dodd, Imy Harper and Margaret Sessa-Hawkins

People in this episode

Host: Marnie Chesterton

Guest: Charles Spence

Topics covered

  • chocolate science
  • microbial communities
  • dark matter
  • taste influence
  • cocoa tree pollination
  • onion tears
  • moth rediscovery

Keywords

  • cocoa
  • chocolate
  • dark matter
  • taste
  • microbial communities
  • pollination
  • onions
  • moth

Mentioned in this episode

Organizations: BBC World Service

Places: South Africa

More episodes of Unexpected Elements

Explore listener stats, chart rankings, contacts and more on the Unexpected Elements podcast page.