Protein microgels: Researchers develop colloidal technique to unlock plant-based juiciness without adding fat

14 Aug 2023 --- A new technique developed by researchers at the University of Leeds in the UK could make plant-based meat alternatives more appealing to consumers by enhancing their texture and mouthfeel. The method involves creating tiny gel-like particles from plant proteins and water, which mimic the sensation of fat and juiciness when eaten.

The technique is proposed as a solution to overcome the dry and astringent mouthfeel of some plant-based foods. Nonetheless, more studies are needed.

“We believe continuous processing is indeed feasible. We also envisage that this can be integrated within a food product processing flow for manufacturing a food, for instance, converting the plant proteins into a microgel and adding them into the food product during formulation,” Anwesha Sarkar, Professor in the School of Food Science and Nutrition at the University of Leeds, tells Food Ingredients First.

“However, since the microgel contains a significant proportion of water, it can be challenging to handle. Hence, a systematic study is needed to understand the upscaling and distribution challenges.”

Scientists use microgels in a process called microgeletion.

What is microgeletion?
The researchers start with plant proteins that are dry and coarse. They soak them in water and heat them. This changes the shape of the protein molecules, which stick together and form a gel that holds, “traps,” water around the plant proteins.

The gel is then homogenized, splitting into tiny particles invisible to the eye. These particles release water under pressure, such as when they are chewed. This gives them a smooth and creamy feel in the mouth.

How the plant protein microgels were developed. (Image Credits: University of Leeds.)“We have converted the dry plant protein into a hydrated one, using the plant protein to form a spider-like web that holds the water around the plant protein. This gives the much-needed hydration and juicy feel in the mouth,” explains Sarkar.

 “Plant-based protein microgels can be created without using any added chemicals or agents using a widely available technique and currently used in the food industry.”

“The key ingredient is water.”  

Dryness a bottleneck
The scientists flag in the study findings, published in the scientific journal Nature Communications, that the dryness of plant proteins is a “key bottleneck for consumer acceptability.”

Scientists hope the better taste will revitalize the plant-based sector, with microgels at the forefront to “offer a unique platform to design the next generation of healthy, palatable and sustainable foods.” 

Plant-based has gathered pace for several years, however, the category has hit some roadblocks recently, underscored by Innova Market Insights’ Top Ten Trends for 2023. Trend #4 “Plant-Based: Unlocking a New Narrative” highlights how the sector requires a refocus on consumer demands for high-quality, flavorful products. 

Having matured considerably over the last decade, the plant-based sector is continuously refined and reimagined through new ingredient discoveries. 

Among the latest solutions rolled out this year are heat-activated natural colors that enable a visual transformation similar to that seen in real meat. Other introductions include multifunctional ranges, such as white vegetable bases that reduce sugar content while also providing texture.Some roadblocks in plant-based make it necessary to explore how to refocus on consumer demands for high-quality, flavorful products.

Last week, Franklin Farms unveiled its latest plant-based offering with the launch of Chickpea Tempeh. The launch taps into consumer trends toward legumes such as chickpeas, beans and lentils which are emerging as the preferred ingredients for plant-based food, indicating a desire for familiar natural protein sources.

Replacing fats in plant-based
Microgel’s lubricity and creaminess could allow them to have other uses in the food industry. For example, they could replace the fat from some foods to make them healthier.

“This is what was quite an interesting finding. Indeed our results show that the microgels offer similar lubricity to 20% oil-in-water emulsions without adding any fat. Based on the tribology and rheology data, we can say that the microgelation offers a great strategy for reducing fat. However, to be definitive, this needs testing when microgels are incorporated in food products via sensory studies,” Sarkar explains.

 “Our experimental data supported by theoretical analyses also mean we could begin to use these plant protein microgels in foods where fat has to be removed to reformulate into healthier next-generation plant protein food options,” adds Ben Kew, doctoral student in the School of Food Science and Nutrition at Leeds University and lead researcher of the project.

Examining mathematical models
The research team used math to predict how the plant protein microgels would behave. But they needed to see it for themselves.

They used a special microscope in the Leeds engineering faculty to zoom in on the molecules. The microscope has a tiny probe that scans the surface of a molecule and creates an image of its shape.

According to the scientists, the images confirmed what the team had expected and what the photos revealed amounted to a proof of concept.

“Seeing the images from the atomic force microscope was an exciting moment for us. The visualizations revealed that the protein microgels were pretty much spherical and not aggregating or clumping together. We could see individually spaced plant protein microgels. 

How the microgels look under a high-powered force microscope. (Image Credits: University of Leeds). “Our theoretical studies had said this is what would happen, but there is nothing quite like seeing it for real.” 

 “This study reveals the ingenuity and depth of science involved in modern food technology, from the chemistry of proteins, the way food is sensed in the mouth to an understanding of tribology – the friction between materials and sensory cells in the mouth,” adds Dr. Mel Holmes, associate professor in the School of Food Science and Nutrition at Leeds and one of the authors of the paper.

 Making food science interdisciplinary
Tackling the key questions in food science requires interdisciplinary science, according to the researchers. Particularly, in this work, Sarkar explains that a combination of food colloid science, physics, mathematics and mechanical engineering was used to not only design these microgels, characterize their properties but also to understand the fundamental mechanism behind how these microgels reduce friction. 

“Such theoretical modeling gives confidence to the observed data and also allows us to think beyond this study to apply such underpinning science to solve other challenges that involve lubrication failure,” she notes.

“The entire food safety area relies on understanding chemistry, microbiology and identifying relevant processes through various mathematical modeling approaches. Nevertheless, in recent times there has been increased attention to solve various issues in food science, which definitely needs further focus on interdisciplinary sciences.”

“Going forward, there is now increased attention in data science and machine learning and therefore computer science to predict and streamline processes,” Sarkar concludes. 

By Marc Cervera