A research team transformed plant-based proteins from dry to juicy and fat-like by creating microgels that trap water and enhance texture and mouthfeel without adding any chemicals. The findings are expected to increase consumer interest in plant-based proteins and contribute to global climate change goals by reducing reliance on animal products.
One of the biggest barriers to adopting plant-based meat alternatives is that they often taste dry and astringent when eaten. A team of scientists, led by Professor Anwesha Sarkar from the University of Leeds, is pioneering the idea of changing the texture of plant proteins. They are working to change people's perception of plant protein from a slimy, dry feel to a juicy, rich feel, similar to fat. And the only thing they add to the plant protein is water.
Plant protein microgel
To achieve this change, scientists created plant protein microgels through a process called microsolization.
The vegetable protein starts out dry and has a rough texture, it is put into water and heated. This changes the structure of the protein molecules so that they clump together, forming an interconnected network or gel that traps water around the plant proteins.
The gel is then homogenized, breaking down the protein network into tiny particles that cannot be seen with the naked eye. Under pressure, as when consumed, the microgels ooze water, creating a lubricating effect similar to single cream.
Analysis using an atomic force microscope revealed that the plant protein microgels did not clump together but were filled with water. Image source: Ben Kew, University of Leeds
Professor Sarkar said: "What we do is convert dry plant protein into hydrated plant protein, using the plant protein to form a spider web that holds water around the plant protein. This provides much-needed moisture and a juicy feel to the mouth. Using technology now widely used in the food industry, we can create plant protein microgels without adding any chemicals or formulations. The key ingredient is water."
Revitalize consumer interest
The team published their findings in the scientific journal Nature Communications and said the dryness of plant proteins has been "...a key bottleneck in consumer acceptance".
With this breakthrough, the team hopes to revive consumer interest in plant-based proteins and encourage people to reduce their reliance on animal products for protein intake, a necessary step to meet global climate change goals.
More than half of the 18 billion tons of carbon dioxide equivalent produced by food production each year comes from the raising and processing of animal products. The researchers say the protein microgels "...provide a unique platform for designing the next generation of healthy, tasty and sustainable food products".
Throughout the study, the team mathematically modeled the behavior of the plant protein microgels and were confident that their approach would work.
But visualizations produced at the Atomic Force Microscopy Suite at Leeds' School of Engineering and Physical Sciences prove this point. Atomic force microscopy uses a tiny probe to scan the surface of a molecule to obtain an image of its shape. These images amount to a proof of concept.
Plant proteins start out clumpy and poorly hydrated. Add water and heat it. The protein changes shape and traps water around itself, forming a gel. The gel is broken down into plant protein microgels, with plant protein particles surrounded by water. Image source: Ben Kew, University of Leeds
Professor Sarkar added: "Seeing the atomic force microscopy images was an exciting moment for us. The visualization showed that the protein microgels were essentially spherical in shape and did not aggregate or clump together. We could see independently spaced plant protein microgels. Our theoretical studies had said this was what would happen, but there was nothing like seeing it happen firsthand."
Dr Mel Holmes, associate professor in the School of Food Science and Nutrition at the University of Leeds and one of the paper's authors, said: "This research reveals the ingenuity and depth of the science involved in modern food technology, from the chemistry of proteins and how food is sensed in the mouth to an understanding of tribology - the friction between materials and sensory cells in the mouth. Solving big questions in food science requires interdisciplinary science."
Given the lubricity of microgels (similar to that of single cream), this means they could be used for other purposes in the food processing industry, such as replacing fat that has been removed from foods to develop healthier foods.
Ben Kew, a PhD student in the School of Food Science and Nutrition at the University of Leeds and lead researcher on the project, said: "This is a really remarkable finding. Surprisingly, the microgels have lubricity similar to that of a 20% fat emulsion without adding a drop of fat, and we are the first to report this."
"Our experimental data are supported by theoretical analysis, which also means we can start using these plant protein microgels in foods where fat must be removed, reformulating into healthier next-generation plant protein foods."