Less bitter, just as satiating
New study on pea protein hydrolysates delivers surprising findings
image:
First author Katrin Gradl at work in the cell culture lab of the Leibniz Institute for Food Systems Biology
view moreCredit: photo: Joseph Krpelan / Leibniz-LSB@TUM
A recent study by the Leibniz Institute for Food Systems Biology at the Technical University of Munich shows that less bitter-tasting pea protein hydrolysates can induce just as strong satiety signals in stomach cells as their more bitter counterparts. The key factor is that new bitter-tasting protein fragments are formed in the gastric juice during digestion, which stimulate the release of gastric acid and the neurotransmitter serotonin – both signals contribute significantly to the feeling of satiety in the body. The study results open up new perspectives for the development of plant-based foods that combine health, pleasant taste, and sustainability in a useful way.
Pea protein hydrolysates are powders made from enzymatically or chemically broken down pea proteins. They consist of a mixture of small protein fragments, known as peptides, and free amino acids. They are currently gaining importance in food production because they are considered easily digestible, have a high-quality amino acid profile, and promote satiety.
“However, a major drawback is their often intense bitter taste, which many consumers dislike,” explains Katrin Gradl, first author of the study and doctoral candidate at the Leibniz Institute. “Our goal was therefore to find ways to overcome this taste barrier without losing the satiating effect of the products,” adds principal investigator Veronika Somoza.
The challenge
However, bitter peptides can trigger signals in the stomach that increase the feeling of satiety. Simply reducing the bitter taste of protein hydrolysates could therefore also reduce the satiety effect. “However, our previous studies with milk proteins had shown that such bioactive, bitter-tasting peptides do not necessarily have to be present in the starting product, but can also be formed in the gastric juice during digestion,” explains co-author Phil Richter from Veronika Somoza's team.
Against this background, the research team simulated the gastric digestion of a bitter and a less bitter protein hydrolysate using artificial gastric fluid and then analyzed the newly formed peptides.
Digestion products with a satiating effect
Using chemical and computer-assisted analysis methods as well as sensory tests, the research team identified three bitter peptides in each of the two digestion products. All six peptides stimulated the secretion of gastric acid and the release of serotonin in a human stomach cell line, regardless of the original bitterness of the product. “It was remarkable that the peptides from the less bitter-tasting hydrolysate stimulated serotonin release particularly strongly,” reports Katrin Gradl. In addition, the researchers demonstrated that two types of bitter receptors were involved in inducing satiety signals in the cellular test system.
Conclusion: Even less bitter-tasting pea protein hydrolysates can form bioactive peptides during digestion in gastric fluid, which induce satiety signals via bitter taste receptors. However, Veronika Somoza emphasizes: “Human studies are needed to definitively assess the influence of these peptides on human eating behavior and weight control.” Nevertheless, the study already reveals molecular mechanisms that can be used to optimize the taste of protein hydrolysates in a targeted manner—without limiting the satiating effects triggered by bitter-tasting compounds.
Publication:
Gradl, K., Richter, P., and Somoza, V. (2025). Bitter peptides formed during in-vitro gastric digestion induce mechanisms of gastric acid secretion and release satiating serotonin via bitter taste receptors TAS2R4 and TAS2R43 in human parietal cells in culture. Food Chem 482, 144174. 10.1016/j.foodchem.2025.144174. https://doi.org/10.1016/j.foodchem.2025.144174
Funding:
The IGF project 21916 N of the research association Forschungskreis der Ernährungsindustrie e.V. (FEI) was supported by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) as part of the program for promoting Industrial Collective Research (IGF) based on a resolution of the German Parliament.
More Information:
Plant proteins are considered an environmentally friendly alternative to animal proteins, as their production requires about five to ten times less energy and water and around 80 percent less agricultural land.
Morbid obesity (adiposity) is considered a widespread disease with serious consequences such as type 2 diabetes and certain types of cancer. A protein-rich diet can help to better control body weight as it increases satiety and thus counteracts excessive energy intake. Studies have also shown that encapsulated bitter tasting compounds induce satiety in healthy adults by activating extraoral bitter taste receptors.
Serotonin is one of the most important hormones that regulate food intake. More than 90 percent of the serotonin in our body is found in certain cells of the gastrointestinal mucosa and the nervous system.
Both the intestines and the stomach are involved in hormonal hunger and satiety regulation. Some bitter-tasting compounds can stimulate gastric acid secretion, increase serotonin release from stomach cells, delay gastric emptying, and have a satiating effect. Interestingly, protein fragments such as bitter-tasting peptides and amino acids are also among the bitter-tasting compounds with a satiating effect.
Read also:
Tracking down satiety mechanisms in the stomach / Bitter protein fragments stimulate gastric acid secretion https://www.leibniz-lsb.de/en/press-public-relations/translate-to-englisch-press...
Information about the Institute:
The Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM) comprises a new, unique research profile at the interface of Food Chemistry & Biology, Chemosensors & Technology, and Bioinformatics & Machine Learning. As this profile has grown far beyond the previous core discipline of classical food chemistry, the institute spearheads the development of a food systems biology. Its aim is to develop new approaches for the sustainable production of sufficient quantities of food whose biologically active effector molecule profiles are geared to health and nutritional needs, but also to the sensory preferences of consumers. To do so, the institute explores the complex networks of sensorically relevant effector molecules along the entire food production chain with a focus on making their effects systemically understandable and predictable in the long term.
The Leibniz-LSB@TUM is a member of the Leibniz Association, which connects 96 independent research institutions. Their orientation ranges from the natural sciences, engineering and environmental sciences through economics, spatial and social sciences to the humanities. Leibniz Institutes address issues of social, economic and ecological relevance.They conduct basic and applied research, including in the interdisciplinary Leibniz Research Alliances, maintain scientific infrastructure, and provide research-based services. The Leibniz Association identifies focus areas for knowledge transfer, particularly with the Leibniz research museums. It advises and informs policymakers, science, industry and the general public.
Leibniz institutions collaborate intensively with universities – including in the form of Leibniz ScienceCampi – as well as with industry and other partners at home and abroad. They are subject to a transparent, independent evaluation procedure. Because of their importance for the country as a whole, the Leibniz Association Institutes are funded jointly by Germany’s central and regional governments. The Leibniz Institutes employ around 21,300 people, including 12,200 researchers. The financial volume amounts to 2,2 billion euros.
Original publication:
Gradl, K., Richter, P., and Somoza, V. (2025). Bitter peptides formed during in-vitro gastric digestion induce mechanisms of gastric acid secretion and release satiating serotonin via bitter taste receptors TAS2R4 and TAS2R43 in human parietal cells in culture. Food Chem 482, 144174. 10.1016/j.foodchem.2025.144174. https://doi.org/10.1016/j.foodchem.2025.144174
More information:
Tracking down satiety mechanisms in the stomach / Bitter protein fragments stimulate gastric acid secretion https://www.leibniz-lsb.de/en/press-public-relations/translate-to-englisch-pressemitteilungen/pm-20221011-press-release-bitter-peptides-gastric-acid
Journal
Food Chemistry
Method of Research
Experimental study
Subject of Research
Cells
Article Title
Bitter peptides formed during in-vitro gastric digestion induce mechanisms of gastric acid secretion and release satiating serotonin via bitter taste receptors TAS2R4 and TAS2R43 in human parietal cells in culture.
COI Statement
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Katrin Gradl and Veronika Somoza (corresp. author) reports financial support, administrative support, article publishing charges, and equipment, drugs, or supplies were provided by Leibniz-Institute for Food Systems Biology at the Technical University of Munich. Veronika Somoza reports a relationship with the Leibniz Institute for Food Systems Biology at the Technical University of Munich that includes employment.
