A research team has investigated how protein structures derived from fava beans affect a cellular model of human oral tactile cells. The new findings could help improve how the F&B industry understands texture and mouthfeel, particularly plant-based food.

Scientists from the Leibniz Institute for Food Systems Biology at the Technical University of Munich examined how to optimize the sensory acceptance of plant-based foods. They found that sensory cells respond to mechanical stimuli such as pressure.

Lead author Dr. Sanjai Karanth speaks to Food Ingredients First about trying to close the “knowledge gap” of how food is processed in the mouth.

“While taste and aroma perception have been studied in detail, the physical properties of food and how it’s perceived (mouthfeel), along with its interaction with oral cells and other oral sensory key players have been poorly addressed so far,” he says. 

“This requires a detailed nanoscale approach, which our team is currently undertaking. Finding the right key players. For example, receptor molecules such as mechanoreceptors, and contributors will help to better design food formulations, which can lead to increased acceptance of plant-based foods.”

“Texture perception and mouthfeel is not specific to plant-based foods, but in general to all types of food formulations. For example, we prefer to eat foods that are softer and more comfortable to bite into or chew, and many parameters contribute to this.”

One of which is water retention or hydration. Optimized hydration significantly improves mouthfeel and makes the food product more palatable. However, currently there are several limitations, including processing methods, plant composition and fat, which are holding it back for greater consumer acceptance.

Dr. Sanjai Karanth flags that more detailed research is needed in this regard.

Protein molecules

Protein nanofibrils are special protein molecules organized into tiny structures. They have unique physicochemical properties that can have a lasting effect on the texture and mouthfeel of foods.

Much is known about their formation and physical properties in liquid media, but research has been lacking on how these fibrils affect cells under physiological conditions. There is a lack of studies on cellular model systems that would allow future conclusions to be drawn about the texture perception of protein nanofibrils.

This is what led to the Leibniz Institute’s research.  

The research group leveraged state-of-the-art technologies to investigate how protein nanofibrils from fava beans affect cells of a human cell line of so-called mechanoreceptor cells.

When studying the model cells under physiological conditions, the researchers first found using atomic force microscopy that the nanofibrils roughened the surface structure of the cells without changing their overall elasticity. They further investigated what was happening at the molecular level.

Tests showed that adding the nanofibrils to the cells’ culture medium altered the activity of receptor genes that play a role in the perception of food texture. These included mechanosensitive ion channels such as piezo receptors, and receptors that detect fatty acids. 

Alternative protein sources

Further studies on artificial cell membranes also showed that the fibrils interact with the membranes via lipids, which affects membrane elasticity in this test system.

“We first started our research journey by looking at the biophysics of mouthfeel and the oral receptors involved. However, based on our previous experience in processing proteins as biomaterials, we felt that we could also come up with a plant-based solution that could support mouthfeel and be beneficial to human health, says Dr. Karanth. 

Our main challenge was the selection of the plant protein, as we were looking for the type of protein that is currently integrated into the food supply chain. Fava beans seemed to be an appropriate choice.” 

“We need to remember that we depend on nature for our survival and not vice versa. The current environmental constraints highlight this. Adaptation is the need of the hour, and plant-based proteins are perfect solutions as they have a smaller environmental footprint and are healthier than animal proteins.” 

Although the research is still in its early stages, the biophysical and biochemical results already suggest how nanofibrils can influence the perception of texture and fat. 

“We plan to map the rheological properties of fava bean protein nanofibrils with textural mouthfeel and its contributors. We also aim to explore these fibrils in a multifunctional role so that it can be tuned depending on the type of food formulation but also their plant-based source,” he concludes.