Eating is an extremely complex activity, according to Stefan Baier, Motif FoodWorks' head of food science.
Once food enters the mouth, it gets broken down at different rates by different teeth during chewing. The tongue is constantly in motion, moving the food around to be chewed, tasted and swallowed. And while that's going on, the mouth produces saliva, which is a complex biological fluid important in lubrication and tasting.
The process is similar for everyone, but different in terms of how the mouth, teeth, tongue and saliva interplay. And while this process is really where much of the science of eating and taste happens, there is not much really known about it, and no generally accepted and uniform ways to measure and talk about it, Baier said. It's often a forgotten aspect in product development, and a really important one. After all, he said, if someone eats a juicy steak, they likely won't talk much about how it felt in their mouth. A dry steak, however, will bring many chewing texture-related complaints.
Motif FoodWorks, which uses biotechnology to develop ingredients to mimic properties naturally found in meat, dairy and eggs, is launching a new research partnership with King’s College London and Imperial College London to study how the mechanics of eating impact sensory perception of food. Plant-based meat and dairy analogs have historically had issues with drier mouthfeels when chewed.
"A lot of these issues that we are trying to solve are longstanding problems that are embedded in understanding texture perception," Baier said. "And so we have quite a lot of effort put into the space to start understanding what are the material properties and the physical, chemical attributes that promote positive and negative sensory attributes. Because sensory, at the end of the day, will only tell you that the product is failing, and maybe at what point the product is failing. But the journey does not really tell you why the product is failing."
For such a complicated process as chewing, studying and quantifying that "why" is a daunting task. But Motif is approaching it as both a mechanical and biological process with this partnership. The company is bringing together oral biology and dental experts from King’s College London, with automotive and mechanical engineers from Imperial College. These disciplines are rarely tapped for food science research, much less for the same project.
The partnership is supported by two U.K. grants: one from the London Interdisciplinary Doctoral Program and an Imperial SME grant — with funds from the Imperial College London Careers Service supporting research at a small- or medium-sized business enterprise. Baier is leading the research, in partnership with Thomas Reddyhoff, senior lecturer in Imperial College's department of mechanical engineering and a member of its Tribology Group; Connor Myant, senior lecturer at Imperial College and head of its Advanced Manufacturing Group; and oral biology professor Guy Carpenter at King’s College. The four-year Ph.D. project at King’s will continue through 2025, and the two-year postdoctoral project at Imperial will continue through 2023.
The research centers on determining how astringency — the natural delubrication effect that many plant-based proteins have when eaten — impacts the sensory experience of consuming plant-based food. Baier said solving for this issue would be extremely helpful when formulating plant-based analogs. The study is going to determine through rheology — the area of physics that looks at the flow of matter — and tribology — the branch of science that studies wear, friction and lubrication — a single way to quantify and measure the astringency factor for plant-based proteins.
Baier said that, so far, much of the work to make plant-based proteins less dry when eaten has been a trial-and-error approach. Sensory testing shows that something is or is not palatable, but it provides no measurement of how an item feels and what can be changed, he said.
"Texture is a very complicated phenomenon. The process that happens in your mouth is also very complicated," Baier said. "So I generally like to decouple things and simplify them to understand what the background is so that I can build on that background."
In this research, Baier plans to use a tribometer — a machine used to simulate and measure wear, friction and lubrication — to develop a measuring methodology for the process of mastication. And then, further research will be done to create more of a methodology, adding in variables like how long food is chewed and tasted, as well as the production and function of saliva.
Being able to quantify the impact of all that goes into chewing, tasting and swallowing food will help Motif figure protein astringency into the calculation when developing future ingredients, Baier said. After all, mouthfeel and texture are extremely important to consumers' satisfaction, even though it may be hard for them to explain how these sensory aspects figure into eating plant-based proteins.
Baier compared the issue of solving for astringency issues in plant-based protein with playing the lottery.
"Nobody is excited when they get one number right in the lottery. I don't think you're going to call home," he said. "Texture perception is the same thing. Matching the material properties across one ... scale: fairly easy. Trying to match against multiple dimensions is a lot harder. And so, like in the lottery, in order to get the jackpot, you need to hit several."