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Peptides formed during cheese ripening are crucial for the full-bodied flavor of aged cheeses, known as kokumi. A research team led by the Leibniz-Institute for Food Systems Biology at the Technical University of Munich has now developed a new method to analyze these flavor-relevant peptides precisely, quickly, and efficiently. Based on more than 120 cheese samples, the team has also created a database that can be used in the future to predict flavor development during cheese ripening.
The term kokumi derives from Japanese and refers to a full-bodied and long-lasting taste experience. The taste impression is particularly pronounced in aged cheeses, mainly due to the increasing concentration of gamma-glutamyl dipeptides. These are small molecules that consist of a link between glutamic acid and another amino acid.
Depending on how the two amino acids are linked, researchers distinguish between gamma-, alpha-, and X-glutamyl dipeptides, with the latter two not contributing to the kokumi effect. The high polarity of the glutamyl dipeptides, as well as their great structural similarity with different flavor contributions, represent a major challenge for food analysis.
Efficient analysis method developed
Nevertheless, the team led by principal investigator Andreas Dunkel of the Leibniz Institute has succeeded in developing a new efficient analysis method based on ultra-high performance liquid chromatography-mass spectrometry. For the first time, it can precisely and selectively determine the concentrations of all 56 gamma-glutamyl dipeptide variants in just 22 minutes. Optimized sample preparation makes it possible to analyze 60 cheese samples per day.
“This is a significant improvement compared to other methods. Our tests have shown that our method is faster, more efficient, and yet reliable – it delivers reproducible results and detects even the smallest concentrations,” says first author Sonja Maria Fröhlich, a doctoral student at the Leibniz Institute. To further investigate the influence of ripening time on gamma-glutamyl dipeptide concentrations, the researchers applied the method to 122 cheese samples from Europe and the USA after the test phase. The ripening times of the cheese ranged from two weeks to 15 years.
Mold cultures accelerate flavor development
The results show that, as expected, the concentrations of glutamyl dipeptides increase with increasing ripeness. “Interestingly, the addition of blue and white mold cultures led to significantly higher gamma-glutamyl dipeptide concentrations, even at shorter ripening times,” says Andreas Dunkel, who heads the Integrative Food Systems Analysisresearch group at the Leibniz Institute.
The food chemist adds: “The concentration profiles we have determined for different stages of ripening and different types of cheese can be used in the future as a database for prediction models. The latter could, for example, be used to objectively monitor flavor development during cheese ripening, to shorten ripening times, or to develop new plant-based cheese products with high consumer acceptance.”
“In the sense of an interdisciplinary, food systems biology research approach, one of our goals is to combine analytical research results with bioinformatic methods to develop predictive models suitable to support sustainable food production. This is also the starting point of the project led by Andreas Dunkel,” concludes Veronika Somoza, director of the Leibniz Institute.
Publication: Fröhlich, S.M., Jünger, M., Mittermeier-Kleßinger, V.K., Dawid, C., Hofmann, T.F., Somoza, V., and Dunkel, A. (2025). Towards prediction of maturation-dependent kokumi taste in cheese by comprehensive high throughput quantitation of glutamyl dipeptides. Food Chem 463, 141130. 10.1016/j.foodchem.2024.141130.
https://doi.org/10.1016/j.foodchem.2024.141130
Funding: This IGF project of the research association FEI was funded 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. IGF project 20776 N.
More Information:
About cheese
Cheese is an integral part of the Western diet, with more than 1,000 types currently available. Further studies show that 54 percent of consumers prefer aged cheese to products with a shorter aging period. Only 16 percent prefer shorter-aged varieties.
According to Statista, Gouda, Edam and quark are among Germany's most produced types of cheese. In 2022, the total consumption of Germans was around two million tons, corresponding to a per capita consumption of around 24 kilograms of cheese per year.
Kokumi
Kokumi does not refer to a distinct taste quality such as sweet, sour, bitter, salty, or umami but rather denotes a full-bodied, lasting, rounded, and balanced taste. Etymologists, who study the origin and development of words, ascribe three different meanings to the word kokumi: 1. heavy, dark (as in colors, e.g., dark blue), 2. thick (as in thickened liquids, e.g., sauces), 3. strong (as in espresso).
Contacts:
Scientific Contact:
Dr. Andreas Dunkel
Leibniz-Institute for Food Systems Biology
at the Technical University of Munich (Leibniz-LSB@TUM)
Head of the research group Integrative Food Systems Analysis (ad interim) &
Head of the technology facility Databases
Phone: +49 8161 71-2903
E-mail: a.dunkel.leibniz-lsb(at)tum.de
Sonja Maria Fröhlich
Research group Integrative Food Systems Analysis
Phone: +49 8161 71-2925
E-mail: s.froehlich.leibniz-lsb(at)tum.de
Director of the Leibniz-LSB@TUM:
Prof. Dr. Veronika Somoza
E-Mail: v.somoza.leibniz-lsb(at)tum.de
Press contact at Leibniz-LSB@TUM:
Dr. Gisela Olias
Knowledge Transfer, Press and Public Relations
Phone: +49 8161 71-2980
E-mail: g.olias.leibniz-lsb(at)tum.de
www.leibniz-lsb.de
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.
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Dr. Andreas Dunkel
Leibniz-Institute for Food Systems Biology
at the Technical University of Munich (Leibniz-LSB@TUM)
Head of the research group Integrative Food Systems Analysis (ad interim) &
Head of the technology facility Databases
Phone: +49 8161 71-2903
E-mail: a.dunkel.leibniz-lsb@tum.de
Sonja Maria Fröhlich
Research group Integrative Food Systems Analysis
Phone: +49 8161 71-2925
E-mail: s.froehlich.leibniz-lsb@tum.de
Director of the Leibniz-LSB@TUM:
Prof. Dr. Veronika Somoza
E-Mail: v.somoza.leibniz-lsb@tum.de
Fröhlich, S.M., Jünger, M., Mittermeier-Kleßinger, V.K., Dawid, C., Hofmann, T.F., Somoza, V., and Dunkel, A. (2025). Towards prediction of maturation-dependent kokumi taste in cheese by comprehensive high throughput quantitation of glutamyl dipeptides. Food Chem 463, 141130. 10.1016/j.foodchem.2024.141130.
https://doi.org/10.1016/j.foodchem.2024.141130
https://de.statista.com/themen/3091/herstellung-und-konsum-von-kaese/#topicOverv... According to Statista, Gouda, Edam and quark are among Germany's most produced types of cheese. In 2022, the total consumption of Germans was around two million tons, corresponding to a per capita consumption of around 24 kilograms of cheese per year.
Loading sample material into a mass spectrometer
J. Krpelan
Leibniz-LSB@TUM
Sonja M. Fröhlich and Dr. Andreas Dunkel in the lab
G. Olias
Leibniz-LSB@TUM
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Loading sample material into a mass spectrometer
J. Krpelan
Leibniz-LSB@TUM
Sonja M. Fröhlich and Dr. Andreas Dunkel in the lab
G. Olias
Leibniz-LSB@TUM
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