Food color overhaul: Scientists unlock innovative fermentation process to formulate betanin from yeast

06 Dec 2023 --- Betalanins — pigments that give red beets their distinctive hue — find a host of applications in F&B, ranging from meat substitutes to candies and ice creams. However, traditional methods of extracting betanin — the most recognized betalanin — are wasteful as their concentration in the root vegetable can be as low as 0.2% of its wet weight.

Now, scientists in Denmark have developed an alternative method to overcome this hurdle — an innovative fermentation process that produces natural betalain-type food colors using Yarrowia lipolytica, an oleaginous yeast commonly found in cheese.

The researchers metabolically engineered the yeast to optimize its cellular metabolism, thereby formulating enhanced betalain-type food colors and reduced by-products, in turn staving off undesirable browning.

"We produce betanin by fermentation of an engineered microbe. Betanin is secreted into the broth and purified. The resulting pigment solution will not contain sugars, as is the case with beetroot extract and could be made in a more concentrated form if desired," Irina Borodina, professor at the Technical University of Denmark, Novo Nordisk Foundation Center for Biosustainability (DTU Biosustain) in Denmark which conducted the study and one of the authors of the research, tells Food Ingredients First. 

"The manufacturing process is analogous to the numerous existing processes for the production of enzymes, insulin, lactic acid for polylactide plastic, vitamins, and so on."

Betanin is a red colorant extracted from red beetroots and marketed as the food additive “beetroot red” (E162)."Betalain colors are diverse healthy pigments with antioxidant properties. Yet, their abundance in edible plants is low and the alternative for fermentative production was not developed. So it was both a useful and technically interesting problem to solve," she informs.

What’s truly "revolutionary" about the process is not just its sustainability and potentially lower cost, but also its capability to produce a higher purity product. 

“Furthermore, the current process presents a platform from which we can expand to making other betalanin-type colors, which are currently too expensive to be extracted from plants,” she adds.

The technique — published in Nature Microbiology — is touted to “revolutionize” the food color industry by offering a more sustainable and efficient alternative to traditional extraction methods similar to brewing beer.

During the study, beetroot red was formulated in water or as a spray dried maltodextrin powder with a betanin concentration of 0.4–1.2%.

Pigment extraction challenges
The study describes betanin as a red colorant extracted from red beetroots and marketed as the food additive “beetroot red” (E162). 

“Beetroot red is increasingly being used to replace synthetic pigments, such as Allura Red AC (E129), which is banned in several EU countries. Although natural dyes can be extracted from cultivated plants, extraction is inherently wasteful and inefficient owing to the low content of pigments natively found in these plants,” detail the authors.

For instance, red beets contain ~20–210 mg betanin per 100 g fresh weight, depending on the cultivar. Moreover, pigment extraction is challenging, with a typical product recovery of only 60%, underscores the study.

Further, while extracting colors from nature, harsh processing conditions like pH instability and prolonged exposure to high temperatures impact the color’s visual and sensory appeal. 

 "Betanin is secreted into the broth and purified," explains Borodina (Image credit: DTU).Additionally, certain colors can bleed or create stains, while ingredients in highly colored foods may produce off-notes when processed.

Nature pays the price 
Awareness of the health implications of consuming artificially colored foods is driving consumers to look for clean label colors that satisfy their conscience about making eco-friendly choices.

The DTU team’s findings warn that the arable land required to satisfy the food industry’s demand for the natural red pigment is predicted only to increase.

“Biosynthetic production of betanin from renewable feedstocks using microbial fermentation could provide a more sustainable and lower-cost alternative to extraction of the pigment from plants,” underscores the study.

Further, GNT also stresses that sustainability is first, even if it is a challenge. There is no room for greenwashing, with manufacturers now expecting hard data to support environmental claims.

Previous attempts at extracting the red pigment targeted Nicotiana benthamiana, Solanum lycopersicum (tomato) and Oryza sativa japonica (rice), producing up to 270 mg betanin per 100 g fresh weight — notably more than typically found in red beets, states the study. But these plant-based betanin production systems are similarly dependent on arable land and climate and seasonal variations impact yields. 

“For microbially produced betanin to be a viable alternative to plant-extracted betanin, it must be cost-competitive, which requires efficient production,” underscores the study.

Ecological impact assessment
To ascertain the method’s ecological impact, researchers from the Sustainable Innovation Office at the university conducted a comprehensive life cycle assessment of the new fermentation process.

“Our findings indicate that the fermentation-based process uses significantly fewer resources, energy and land when compared to traditional betanin extraction from beets,” details Dr. Sumesh Sukumara, senior researcher at the Novo Nordisk Foundation Center for Biosustainability and one of the co-authors of the study.

“In effect, if we harness the potential of this fermentation-based color production fully, we can satisfy the world’s demand with just one-tenth of the equivalent land area.”

Comparison of the supply chain of extraction-based betanin production with that of the proposed fermentation-based process (Image credit: Nature Microbiology).

Market potential
Betalain colors are already widely used natural food colors in candies, beverages and ice cream. The availability of fermented natural pigments of higher concentration and purity than plant extracts will likely expand the application areas, flags Tue Rasmussen, business developer at Tura Consult, which is helping DTU commercialize the technology.

"We already see interest from color houses and ingredient producers, so the market is already reacting at this early stage."

Earlier this year, California banned red dye No. 3 used in processed food and drink."Precision fermentation techniques have the potential to supply bright and intense natural colors with an improved environmental footprint compared to plant extraction. And that at an attractive cost structure, so we foresee a shift towards fermentation derived natural colors over the coming years," he concludes.

Phasing out artificial dyes
Artificial dyes have been facing the heat of regulators for quite some time. Earlier this year, California banned red dye No. 3, along with three other food additives used in processed foods and drinks, over their potential link to cancer and behavioral problems in children.

As previously reported by Food Ingredients First, F&B’s innovation efforts regarding natural colors have gathered pace amid greater scrutiny of specific color sources, such as TiO2 and Red No. 40.

For instance, Danish biotech company Chromologics’ has formulated Natu. Red, a natural color formulated from a non-GMO filamentous fungus via precision fermentation, which it says has a “stable cost structure and a better sustainability profile than betanin and carmine.”

By Insha Naureen