Scientists invent ‘cruelty-free’ foie gras

By Stephen Beech

A cruelty-free way of making foie gras has been devised by scientists.

Made from the liver of a duck or goose, the buttery, fatty dish is considered a delicacy, and is prized in many parts of the world.

But traditionally made foie gras has been the subject of protests by animal welfare activists as its production involves the force-feeding of birds.

It was taken off the mune at London's Playboy Club in 2019 following complaints led by former Baywatch icon and vegan campaigner Pamela Anderson.

Several countries and regions have laws against force-feeding or the sale or importation of foie gras.

For example, foie gras production has been banned in Switzerland since 1978, and, even where it is legal, some retailers have ceased selling it.

Now researchers have come up with a way of making it without force-feeding.

The team has patented the recipe, described in the journal Physics of Fluids.

They explained that foie gras is distinct from regular fowl liver thanks to its high-fat content, which is traditionally achieved by force-feeding ducks and geese beyond their normal diets.

Professor Thomas Vilgis, himself a lover of foie gras, wondered if there was a more ethical way to enjoy the dish.

He and colleagues at the Max Planck Institute for Polymer Research in Germany and the University of Southern Denmark created a process to replicate the dish without force-feeding.

Vilgis said: “It was always a dream to make foie gras more accessible and better for animal welfare.

“It’s good to stop these force-feeding practices - or at least reduce them.”

It was important to the research team not to add external ingredients or additives to the foie gras.

They tried adding cooked collagen from the bird’s skin and bones to the liver and fat emulsion after it was harvested, but that didn’t leave them with the correct consistency.

The team then came up with the idea of trying to treat the fat with the bird’s own lipases - enzymes that help digest fat in the body, mimicking the activities that occur naturally in the duck’s body.

Vilgis said: “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."

He described the recipe as "extremely simple and elegant".

Vilgis says the liver and fat are harvested from the duck or goose, the fat is treated with lipases, both are mixed and sterilized, and it’s good to go.

But while the structure of the foie gras looked correct with non-invasive laser microscopy - and even smelled like the original foie gras - Vilgis and his team needed to confirm the physical properties of the dish.

By conducting stress-deformation tests, they found that the treated foie gras had a similar "mouthfeel" to the original, due to its mechanical properties.

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

“At the beginning of the ‘bite,’ these large clusters have a high resistance, creating a similar mouthfeel of elasticity without being too rubbery as after the collagen or gelatin addition.”

Vilgis has already filed a patent for the recipe, and he hopes to partner with companies interested in helping scale up the production.

He also wants to work with sensory scientists who can help refine the taste and smell of the foie gras.

Vilgis added: “Everything in our process is controlled, which is a positive thing.

“We never considered adding anything additional to the foie gras, because we wanted pure duck - nothing else.”