Kopi Luwak beans cost over ,000 a kilogram.© Photodisc

A food scientist has cracked the secrets of the world's most expensive coffee, Kopi Luwak, whose beans pass through the intestinal tract of an Indonesian civet before being roasted and savoured. But the elusive blend looks unlikely to be copied any time soon.

The beans, which cost over US$1,000 a kilogram, are eaten and passed by the Asian palm civet (Paradoxurus hermaphroditus), which is a musky, tree-climbing cat-like creature. The supply of Kopi Luwak has always been tiny, but political turmoil in Indonesia has strangled production even further: less than 230 kilograms of the coffee are now being made each year.

Massimo Marcone, a researcher at the University of Guelph in Ontario, Canada, wondered whether it might be possible to reproduce the effect that the Indonesian civets have on the coffee. He searched the world for another place with both coffee plants and civets, and hit upon Ethiopia, where coffee itself was born.

"It was something I was just dreaming up," he says. "Where else do we have coffee and the cat in a similar place?" In a forthcoming issue of Food Research International¹, Marcone describes how he brewed coffee from beans that he personally picked out of the faeces of African civets (Civettictis civetta) and compared it with a mug of Kopi Luwak.

Marcone found that in both cases the civets' digestive action broke down proteins in the beans into smaller molecules that added to the flavour and aroma of the coffee on roasting. Some proteins were leached out of the beans completely, making the resulting coffee less bitter.

Bragging rights

Kopi Luwak was not as easy to copy as Marcone had hoped: the guts of the Indonesian civets did a much more thorough job of breaking down the proteins than did the digestive systems of the African civets.

But Marcone also discovered that the slow passage through the bacteria and enzymes in the civet's gut is similar to a method of fermenting coffee called the wet process. They even use the same agent: lactic acid bacteria.

He is sure that he could tweak the wet process to be a better approximation of the inside of a civet, perhaps by using the same strains of lactic acid bacteria. But he is not sure the simulation is worth it. "If we were able to develop it, you would lose the bragging rights that this is the rarest and most expensive coffee in the world," he says.

And ultimately, it is those bragging rights that matter. Despite being described by some as "earthy, musty, syrupy, smooth and rich, with both jungle and chocolate undertones", Marcone admits that Kopi Luwak is "different from, but not better than, other coffees". 

• References

  1. Marcone M. . Food Research International, in press, (2004).