Faux gras? Scientists craft 'more ethical' version of French delicacy

Foie gras — the fattened liver of ducks or geese — is a French delicacy prized for its rich, buttery flavor. But its production, which involves force-feeding the animals, has led to bans in several countries.

Now, a team of scientists says they've developed a more ethical alternative: one that mimics the taste and texture of the dish, minus the controversy.

The results have been published in the journal Physics of Fluids.

"It was always a dream to make foie gras more accessible and better for animal welfare," said lead author Thomas Vilgis, a professor of food science at the Max Planck Institute for Polymer Research in Mainz, Germany. "It's good to stop these force-feeding practices - or at least reduce them."

Vilgis and his colleagues from his own institute and the University of Southern Denmark were adamant about one thing: their creation should include no outside additives.

They initially tried cooking collagen from the birds' skin and bones into the liver-fat emulsion, but the result lacked the signature silky texture.

Then came the breakthrough: treating the fat with the bird's own lipases: enzymes the body naturally uses to break down fats. This tweak replicated a key part of the foie gras formation process, without resorting to force-feeding.

"At the end of the process, it allows the fat to recrystallize into the large crystals which form aggregates like the ones we see in the original foie gras," Vilgis said.

According to the authors, the elegance of the method lies in its simplicity: harvest the liver and fat, treat the fat with lipases, mix and sterilize.

Laser microscopy helped provide the new product's emulsion structure, fat droplet size, and shape so it closely matched traditional foie gras. 

To test texture, the team turned to industrial compression devices - machines that gently press on food samples to measure firmness. The researchers said the new foie gras held up well, offering a mouthfeel strikingly close to the original.

"We could really see the influence of these large fat particles, which we call in the paper 'percolating clusters,'" Vilgis said.

"At the beginning of the 'bite,' these large clusters have a high resistance, creating a similar mouthfeel of elasticity - without being too rubbery like after the collagen or gelatin addition."

Vilgis has filed a patent for the process and now hopes to partner with companies to bring this kinder foie gras to market.