From Crop to Consumption

Making cheese & co. taste better

Researchers at the Technical University of Munich, the Leibniz-Institute for Food Systems Biology, and the University of Hohenheim have developed a new methodical approach.

It 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 more than one thousand 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.

A team of scientists led by Professor Thomas Hofmann, Head of the Chair of Food Chemistry and Molecular Sensory Science at 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 from 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.

The researchers started their work with an extensive review of the literature. They concluded that a total of approx. 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.

Prof. Hofmann, who is also the Director of the Leibniz-Institute for Food Systems Biology at TUM, is convinced that “The sensoproteomics approach we have 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.”