Wednesday, March 26, 2025

 FOOD CHANNEL PHYSICS  NEWS

Making foie gras without force-feeding



Authors patent recipe using existing fats after harvest to improve animal welfare for luxury dish.



American Institute of Physics

A stress test of the researchers’ foie gras pâté, which is created without the need for force-feeding. 

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A stress test of the researchers’ foie gras pâté, which is created without the need for force-feeding.

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Credit: Thomas A. Vilgis




WASHINGTON, March 25, 2025 — Foie gras is a unique delicacy made from the liver of a duck or goose. While it can be an acquired taste, the buttery, fatty dish is an indulgent cuisine prized in many parts of the world.

Foie gras is distinct from regular fowl liver thanks to its high fat content, which is traditionally achieved by force-feeding the ducks and geese beyond their normal diets. Researcher Thomas Vilgis is a lover of foie gras, but he wondered if there was a more ethical way to enjoy the dish.

In Physics of Fluids, by AIP Publishing, Vilgis, as well as researchers from Max Planck Institute for Polymer Research and the University of Southern Denmark, created a process to replicate the delicious dish without force-feeding.

“It was always a dream to make foie gras more accessible and better for animal welfare,” Vilgis said. “It’s good to stop these force-feeding practices — or at least reduce them.”

To Vilgis and his team, it was important 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.

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

“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.

The recipe is extremely simple and elegant — 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.

However, while the structure of the foie gras looked correct with noninvasive laser microscopy — and even smelled like the original foie gras — Vilgis and his team needed to confirm the physical properties of the dish. By doing stress-deformation tests, they found that the treated foie gras had a similar mouthfeel to the original, due to its mechanical properties.

“We could really see that 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 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 smell of the foie gras.

“Everything in our process is controlled, which is a positive thing,” Vilgis said. “We never considered adding anything additional to the foie gras, because we wanted pure duck — nothing else.”

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The article “Foie gras pâté without force-feeding” is authored by Mathias Baechle, Arlete M.L. Marques, Matias A. Via, Mathias P. Clausen, and Thomas A. Vilgis. It will appear in Physics of Fluids on March 25, 2025 (DOI: 10.1063/5.0255813). After that date, it can be accessed at https://doi.org/10.1063/5.0255813.

ABOUT THE JOURNAL

Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex fluids. See https://pubs.aip.org/aip/pof.

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The best butter for a vegan shortbread


Experimental tests determine the optimal fat content of vegan butter to bake the Scottish staple.



Peer-Reviewed Publication

American Institute of Physics

Scottish shortbread and vegan butter 

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Scottish shortbread, one of the region’s most well-known desserts, served as the perfect testing ground to explore the effects of fat content in vegan butter alternatives. Credit: Avery Thompson/AIP

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Credit: Avery Thompson/AIP




WASHINGTON, March 25, 2025 – Butter is a key ingredient in many baked goods, but for those who are lactose intolerant, finding a good alternative can be a challenge. Vegan butters can sometimes have the wrong consistency, or produce bakes that are not quite right, leaving bakers frustrated or unwilling to try dairy-free alternatives.

In Physics of Fluids, by AIP Publishing, researchers from the University of Strathclyde examined the properties of several vegan or dairy-free butter alternatives inside one of the region’s most well-known snacks: Scottish shortbread.

“We have a Ph.D. student in the group who is a vegan, and he turns all of our baking habits upside down,” said author Juliane Simmchen. “One day I bought some vegan butter alternatives, and I thought, ‘This doesn't look anything like it should.’”

Perplexed by the difference in consistency, Simmchen and her colleagues decided to test these alternatives using the equipment in their lab. They selected three types of vegan butter substitutes with different levels of fat and compared their consistencies and responses to heat. Following those experiments, they moved on to taste testing with actual biscuits.

The researchers gathered a few dozen volunteers to sample shortbread cookies baked with dairy butter and the vegan alternatives. Their goal was to find the vegan butter that produced a biscuit closest to the traditional shortbread, and here there was a clear winner.

“When comparing the vegan alternatives, the one with the highest fat content gave the most positive results from the testers,” said Simmchen. “It behaved very similar to butter, which also has a high fat content. The one with the lowest fat content made a very different dough. It didn't bake that well, and was more doughy and less crumbly. Many people strongly disliked it.”

Butter typically has a fat content around 80%, and Simmchen recommends choosing a vegan butter with a similar consistency.

As for why people should bake vegan cookies in the first place, Simmchen believes that baked goods are better when they can be shared with everyone. If she has a choice, she now prefers vegan bakes.

“I really like the traditional Scottish shortbread, but I'm adapting my recipes with vegan options because they’re more inclusive,” said Simmchen. “If I can make something of a similar quality and have more people participate, then I go for the vegan option.”

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