The world of cheese is so extraordinarily diverse that there is no consensus regarding the number of varieties of this food produced since ancient times. But all hundreds of typesor even Thousands, have something in common: they are full of bacteria, yeasts and molds. Although science knows in depth the activity of these microbes during the milk fermentation process that gives rise to cheese, it remains a mystery how they determine its aroma and flavor. An international research team has set out to unravel how microorganisms make cheddar, one of the most popular cheeses in the world, so peculiar. And the results of that scientific effort were made public this Thursday in the magazine Nature Communications.
Knowing exactly the role of microbes in both the functioning of our body and the properties of food is a field of growing interest for science. We already knew that lactic acid bacteria, for example, produce compounds called acetoin and diacetyl, which are also found in butter, which is why some cheeses taste that way. Also that the yeast Geotrichum candidum It produces a mixture of alcohols, fatty acids and other compounds that is responsible for the fruity aroma, characteristic of cheeses such as brie or camembert.
Now the focus of the research is placed on cheddar, originally from the English county of Somerset, which has become a gastronomic classic in many countries and accompanies all types of dishes, melted into hamburgers and sandwiches or gratin on pasta. To address the secret of the flavor of the popular cheddar, microbiologists Chrats Melkonian, Ahmad Zeidan and their colleagues at the food science company Chr. Hansen in Denmark did experiments for a year with batches of this cheese, using variants of a culture with combinations of bacteria strains.
“It's a novel approach,” he says. Baltasar Mayoresearch professor at Institute of Dairy Products of Asturias (CSIC), which has not participated in the study. Mayo explains that microorganisms in food are constantly studied, but it is not common to do so over 12 months during the production of cheese. Thanks to this way of approaching it, the authors of the study discovered the crucial role of Streptococcus thermophilus in the growth of other bacteria, Lactococcuswhich in turn turned out to have a significant impact on flavor: the presence of Lactococcus cremoris limited the formation of unpleasant compounds and, on the other hand, the elimination of certain strains of Lactococcus revealed the presence of specific compounds, highlighting the importance of each component in the flavor palette.
Throughout the experiment, the researchers observed a specific population dynamic, within which they highlight the relevance of Streptococcus thermophilus in the microbial community, especially between two weeks and three months. The absence of this bacteria resulted in notable differences in compound concentration over time, evidencing both its critical role in growth during fermentation and its long-term effect on flavor development. Francisco Zorrilla, co-author of the study from the University of Cambridge, highlights that they also identified another competitive interaction (between Lactococcus cremoris and the Lactococcus lactis) for the nutrients available in milk, which is associated with fruity, creamy and nutty flavors of the final product.
How to mix bacteria and predict flavor
According to Mayo, “it is complex to decipher what function each thing has within the matrix where many types of chemicals and reactions are found.” Regarding this complexity, Zorrilla highlights that flavor depends not only on individual microbes, but also on the interactions between them: “This represents an important consideration for future applications,” he says, adding that the findings of his study can provide tools to the Rational design of microbial communities for a wide range of cheeses.
This research, however, not only sheds light on the secrets of cheddar cheese flavor, but also opens the door to new applications in the food industry in general. Mindful manipulation of microbial combinations could improve flavor consistency and quality in growing fields such as novel plant-based foods. According to another of the study's authors, Chrats Melkonian, the elimination of unwanted flavors and toxic compounds, “is essential to achieve a pleasant and safe final product.” Francisco Zorrilla points out that more experiments and research are needed, but anticipates that in the future “artificial intelligence can be used to predict which organisms and in what quantities can produce desirable flavors.”
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