Cheese hues: UK researchers unlock novel fungal strain for varied cheese colors

(Image credit: University of Nottingham).

19 Feb 2024 --- Scientists at the University of Nottingham, UK, have formulated a variety of different fungal strains that could be used to make cheese with colors ranging from white to yellow-green to red-brown-pink and light and dark blues.

Using a combination of bioinformatics, targeted gene deletions and heterologous gene expression, the research team discovered how the classic blue-green veining in fungus Penicillium roqueforti is created to manufacture blue-veined cheese such as Stilton, Roquefort and Gorgonzola.

The researchers found that a biochemical pathway gradually forms the blue pigments, starting at a white color, which progressively becomes yellow-green, red-brown-pink, dark brown, light blue and finally dark blue-green.

The team then employed food-safe (non-GM) techniques to “block” the pathway at certain points, leading to strains with new colors that can be used in cheese production.

“We’ve been interested in cheese fungi for over ten years and traditionally when you develop mold-ripened cheeses, you get blue cheeses such as Stilton, Roquefort and Gorgonzola which use fixed strains of fungi that are blue-green in color. We wanted to see if we could develop new strains with new flavors and appearances,” says Dr. Paul Dyer, Professor of Fungal Biology at the University of Nottingham, UK, who led the study.

The team used non-GM methods to create new fungal strains for varied color derivatives (Image credit: University of Nottingham). “The way we went about that was to induce sexual reproduction in the fungus, so for the first time we were able to generate a wide range of strains which had novel flavors including attractive new mild and intense tastes. We then made new color versions of some of these novel strains.”

The study findings are published in the journal NPJ Science of Food.

Exploring fruity tangy flavors
After formulating the cheese with the new color strains of fungi, the team used lab diagnostic instruments to examine its flavor.

“We found that the taste was very similar to the original blue strains from which they were derived,” reveals Dr. Dyer. “There were subtle differences but not very much.”

The researchers also conducted taste trials with volunteers from the university.

“We found that when people were trying the lighter colored strains they thought they tasted more mild. Whereas they thought the darker strain had a more intense flavor.”

We recently spoke with Dr. Dyer and Dr. Cleere about the tech and potential applications of their innovation.On tasting the more reddish brown and light green cheese, the tasters reported a “fruity, tangy” element to them. In contrast, according to the lab instruments, they were “very similar” in flavor.

“This shows that people do perceive taste not only from what they taste but also by what they see,” he explains.

Testing commercialization
Given the iconic status of P. roqueforti as the “blue-cheese fungus,” the scientists worked to produce strains with new altered spore coat colors, which could exhibit public and commercial appeal for cheese production.

The researchers, which included Matt Cleere, a lead postgraduate student at the university, are now aiming to work with cheese makers in both Nottinghamshire and Scotland in the UK to formulate the color variants of blue cheese.

The university has also established a spin-out company called Myconeos to explore the commercialization potential of the innovation.

“It will give people a really satisfying sensorial feeling eating these new cheeses and hopefully might attract some new people into the market,” concludes Dr. Dyer.

P. roqueforti is commonly used as starter culture in blue cheese, although other fungi may be used in artisanal style blue-veined cheeses.Blue cheese has also caught the attention of industry giants like Lallemand, which recently leveraged Leuconostoc mesenteroides bacteria for optimizing blue cheese production. The culture efficiently and robustly opens the curd, allowing for optimal blue mold development.

Microbes and F&B
Scientists have been examining microbial species for NPD and innovation to develop products that help F&B manufacturers bring novel products for consumers.

In Denmark, researchers leveraged Yarrowia lipolytica, an oleaginous yeast commonly found in cheese to formulate natural betalain-type food colors using metabolic engineering techniques.

Patulin, a harmful mycotoxin produced by fungi found in damaged fruits like grapes, was also targeted last year, when scientists discovered a fungal species that can transform the toxin into less toxic byproducts.

But some microbes are harmful too, such as the fungus, Fusarium TR4, which infects the Cavendish banana plants’ circulatory system and can even wipe out the species. Last year, biotech company Elo Life Systems turned to gene-editing to tackle the issue.

By Insha Naureen

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