Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
November 26, 2002
Kopi luwak coffee safe, U of G study finds
Kopi Luwak coffee — the $600-a-pound delicacy collected from the backside of an Indonesian feral cat called the luwak — is safe, according to a University of Guelph food scientist. After examining the chemical and physical properties of Kopi Luwak coffee, Massimo Marcone found it has lower bacterial counts than regular coffee.
Known as the palm civet in its native country, the luwak feeds on coffee beans. Its stomach acids and enzymes digest the beans' cherry-like covering and ferment the beans themselves, before they're excreted. It's believed that fermentation process could give Kopi Luwak coffee a unique flavour.
The big question is whether passing through the gastrointestinal (GI) tract of the luwak really makes Kopi Luwak coffee beans different from regular beans. So, Marcone and other members of his department completed a series of tests on the Kopi Luwak beans and compared them with Colombian beans.
First, they examined if there was any colour differences between unroasted samples of the two beans. Using a colorimeter – an instrument that detects different colours – they found that the Kopi Luwak beans had more red and yellow tones, whereas the Colombian beans were more greenish in colour.
The surfaces of the two beans were examined using a scanning electron microscope. The Kopi Luwak beans were found to be smoother, indicating that the gastric acids and/or enzymes of the luwak were exfoliating the surface of the bean, said Marcone.
Pitting was also observed on the surface, and the next step was to determine if the acids and enzymes were actually penetrating the Kopi Luwak beans, affecting them in some way. Electrophoresis – a method that "fingerprints" proteins – was used to determine differences in the protein content of Kopi Luwak and Colombian beans. The Kopi Luwak beans were found to be lower in total protein, meaning that proteins were partially broken down and leached out during their travel in the GI tract of the luwak.
The protein composition has the potential to affect the flavour and aroma of the beans, said Marcone. Proteins are responsible for much of the flavour, particularly bitterness. Since Kopi Luwak beans have less protein, they may produce a less bitter coffee, he said.
Analysis of the volatile compounds – also responsible for flavour and aroma – showed they were significantly different than those of the Colombian beans, further indicating the potential for Kopi Luwak coffee to have a different flavour than ordinary coffee.
Formal taste tests were not performed, but Marcone wants to do them in the future. If Kopi Luwak beans produce a taste that consumers enjoy, the digestion occurring in the GI track of the luwak could be mimicked by chemical means, he said. Since only 500 pounds of Kopi Luwak coffee are produced each year, creating the same taste by chemical means could decrease cost and increase production.
"People are buying this product for the mystique, not necessarily for the flavour," he said. "More tests need to be completed to determine if, in fact, a flavour difference is occurring."
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