Foie gras, made using the livers of ducks or geese, is famous as one of the world's three most luxurious delicacies, but it is also notorious for being made using cruel farming techniques, which constitute animal abuse. Recently, there has been a growing awareness that livestock should be raised humanely, leading to movements to eliminate foie gras from menus.
German researchers have succeeded in recreating the taste and texture of foie gras without employing cruel farming techniques. Foie gras flavors and textures can now be produced using the livers of ducks or geese raised in standard methods, thus avoiding controversies surrounding animal abuse.
Thomas Vilgis, a researcher at the Max Planck Institute for Polymer Research, noted on the 26th, "We successfully created flavors and textures similar to foie gras by mixing specific enzymes into the livers of standard ducks or geese." The research results were published in the international journal 'Physics of Fluids.'
Foie gras is typically made using the livers of ducks or geese raised via a specific method called gavage. Gavage involves confining the ducks or geese in a narrow cage and forcibly feeding them through a tube connected to their esophagus to ensure fat accumulates in their livers. This method results in the liver's size increasing approximately tenfold compared to standard farming methods and provides the appropriate flavors and textures for making foie gras. However, this method is quite cruel, which has spurred strong movements in Europe, particularly in the UK and Netherlands, to eliminate foie gras.
Researchers at the Max Planck Institute investigated methods for producing foie gras using livers from ducks or geese that were not raised through the gavage method. They created a pâte, an emulsified food containing beef at the same fat-to-liver ratio as traditional foie gras, but it fell short of replicating the foie gras flavor. Following this, they attempted to recreate the texture of foie gras by adding collagen, but again, it did not achieve the desired smoothness.
Professor Vilgis realized through further research that the flavor of foie gras lies more in the fine distribution of fat rather than in high fat content. The researchers discovered that ducks or geese raised via the gavage method secrete specific enzymes from their pancreas that break down fat. These enzymes effectively chop large fat molecules into smaller crystalline forms within the liver, thus recreating the flavors and textures of foie gras.
The research team found an enzyme similar to the enzymes secreted by the pancreas of ducks or geese raised through the gavage method. They determined that a fat-degrading enzyme extracted from a specific yeast (Candida rugosa) serves a similar role. Professor Vilgis explained, "The yeast's fat-degrading enzyme cuts through fatty tissue like molecular scissors."
The researchers mixed the yeast's fat-degrading enzyme with the livers of ducks and geese raised through standard methods to create foie gras. Analysis of the resulting foie gras using experimental equipment such as nuclear magnetic resonance spectroscopy (NMR) revealed no significant differences compared to foie gras made through the gavage method. Professor Vilgis stated, "Both the taste and aroma were almost indistinguishable from actual foie gras," and added, "When collagen or gelatin were previously added, the texture resembled rubber, but incorporating the fat-degrading enzyme produced a texture similar to foie gras."
References
Physics of Fluids (2025), DOI: https://doi.org/10.1063/5.0255813