Researchers at the Technical University of Munich (TUM), the Leibniz-Institute for Food Systems Biology, and the University of Hohenheim have developed a new methodical approach that allows for the faster identification of flavour-giving protein fragments in foods such as cheese or yoghurt, thus optimising production processes.

The taste of fermented foods, such as cheese, yoghurt, beer, yeast dough or soy sauce, is very popular with consumers worldwide. In addition to volatile aroma compounds, non-volatile substances also significantly contribute to their characteristic taste profile.
Above all, these include fragments of long-protein molecules that are produced, for example, during microbial or enzymatic conversion (fermentation) of milk or grain protein.

At present, however, it is still unclear which of the over 1,000 different protein fragments in fermented milk products are responsible for the flavour. One reason being that previously used analytical methods are very labour-intensive and time-consuming.

New analytical approach provides a solution

A team of scientists led by Thomas Hofmann, head of the chair, food chemistry and molecular sensory science, TUM, has developed a new analytical approach to address this problem.
What makes the approach so innovative is that researchers combined existing methods of proteome research with methods of sensory research to efficiently and quickly identify the decisive flavour-giving protein fragments from the totality of all fragments.

“We coined the term sensoproteomics for this type of procedure,” said Andreas Dunkel of the Leibniz-Institute for Food Systems Biology, the lead researcher for the study.

The team of scientists tested the effectiveness of the newly-developed procedure for the first time on two different varieties of cream cheese with different degrees of bitterness.

The objective was to identify the specific protein fragments responsible for a bitter off-flavour in cheese that occurs under certain production conditions.

An approach to reduce 1,600 possibilities to 17

The researchers started their work with an extensive review of the literature. They concluded that a total of approximately 1,600 different protein fragments contained in dairy products could theoretically be responsible for the bitterness.
Subsequent liquid chromatography-coupled mass spectrometer investigations assisted by in-silico methods reduced the number of potential protein fragments to 340.

Finally, comparative spectrometric, sensory and quantitative analyses reduced the number of fragments responsible for the bitter cheese flavour to 17.

Hofmann, director, Leibniz-Institute for Food Systems Biology, TUM, was convinced that the sensoproteomics approach they developed will in the future contribute to the rapid and efficient identification of flavour-giving protein fragments in a wide range of foods using high-throughput methods — a significant help in optimising the taste of products.

Funding
This research project by the Research Association of the German Food Industry (FEI) received funding from the Otto von Guericke Federation of Industrial Research Associations as part of the Industrial Collective Research programme by the Federal Ministry for Economic Affairs and Energy pursuant to a parliamentary resolution by the German Bundestag.