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South à£à£Ö±²¥Ðã State University's Ananda Nanjundaswamy is developing a natural and safe alternative to synthetic food dyes.  

In April, the U.S. Department of Health and Human Services and the Food and Drug Administration announced a forthcoming

The announcement, while expected, will require most of the nation's food companies to make systemic changes in their food production processes. Synthetic dyes are prevalent in the U.S. food supply and are found in candies, ice cream, drinks and even medications. These synthetic dyes do not add any flavor or nutritional value and are solely used to give foods and other products the colors consumers are long accustomed to.

But a growing body of research links synthetic dyes to significant health problems. Of particular concern is Red No. 3 — a widely used synthetic dye that gives food and drinks a bright, cherry-red color. According to the FDA, Red No. 3 has been linked to cancer in male lab rats and is already banned in food products in Europe, Australia and New Zealand. Other synthetic dyes, like Red No. 40, have been linked to hyperactivity and neurobehavioral problems in children.

Food manufacturers will have until January 2027 to completely phase out synthetic dyes from their foods. Until then, companies may be looking toward innovative biotechnologies — like the one being developed by a lab in South à£à£Ö±²¥Ðã State University's Department of Biology and Microbiology — as a replacement.

Natural pigments

Ananda Nanjundaswamy is SDSU's Richard and Janice Vetter Endowed Associate Professor of Biotechnology and Bioprocessing. His research is focused on bioprocessing and fermentation for product development. In recent years, he has focused his efforts on using microbes — microscopic organisms like bacteria, fungi and algae — for the source material of compounds that may be used in human food and à£à£Ö±²¥Ðã feed.

"In the last few years, my research focus is on natural food color production," Nanjundaswamy said. "Natural food colors are the next alternative to synthetic food dye."

As Nanjundaswamy explains, microbes live naturally on plant surfaces and in the soil and are known to be nature's producers of natural colors. are a class of molecules that are responsible for the naturally occurring pigments in plants and à£à£Ö±²¥Ðãs.

"Carotenoids are a group of molecules which fall into the category of simple lipids," Nanjundaswamy said. "They are produced by fungi, yeast and sometimes bacteria."

There are over 1,100 identified carotenoids, and they can be categorized into two classes: xanthophylls and carotenes. Different carotenoids provide different colors. For example, salmon have a distinct pink or reddish color. This is thanks to the carotenoid astaxanthin, which salmon acquire after consuming algae or krill. Flamingos have a similar response to consuming microbes with astaxanthin.

But it’s not just coloring that carotenoids provide. The molecules also have antioxidant properties, meaning they prevent some types of cellular damage and offer pro-vitamin A activity, adding nutritional value to foods.

"There are two ways these molecules can be used," Nanjundaswamy said. "One is natural colors. The second is as a nutritional molecule."

Using ag byproducts

The Upper Midwest is the U.S.'s largest sugar beet-producing region, and molasses is a byproduct of sugar beets. For most, molasses is a little-used, bulk commodity that can be purchased rather cheaply. In Nanjundaswamy's lab, researchers are using molasses as the carbon source to grow different microorganisms that are known producers of carotenoids.

In benchtop bioreactors, Nanjundaswamy and his team are optimizing the conditions for fungus and yeast to be grown in molasses. As the fungus and yeast grow, the research team is extracting the colorful carotenoids and other useful "goodies" produced by the microbes.

"Carotenoid-producing yeast are also very good producers of lipids," Nanjundaswamy said. "Lipids are very useful for à£à£Ö±²¥Ðãs as well as humans."

Nanjundaswamy's lab is focused mainly on red and yellow colors, which means they are focused on astaxanthin, beta-carotene and other molecules under the carotenoid umbrella. The extracted carotenoids are the end-product of Nanjundaswamy's research, and they can be mixed into different foods to give them rich colors.

In ancient times, natural ingredients were used to add colors to foods. In the middle of the 19th century, scientist William Henry Perkin was credited with discovering the first synthetic dye. By the turn of the century, it was extremely common for foods, drugs and cosmetics to have synthetic dyes in them.

One of the major reasons synthetic dyes became so popular is because they are cheap to produce — far cheaper than natural food colors. This represents one of the major challenges Nanjundaswamy faces in developing commercially viable natural food dyes. Extracting natural pigments is an expensive, inefficient process. But using molasses as a carbon source is one of the ways Nanjundaswamy is circumventing the cost challenges.

"We use these inexpensive agricultural products, like molasses, for our work," Nanjundaswamy said. "The inexpensive coproduct you are generating from one industry can serve as a feedstock for another industry. That's what is known as the circular economy, and that's what's happening here."

Another byproduct Nanjundaswamy is exploring is high fructose corn syrup. In the Midwest, high fructose corn syrup is produced in very high quantities and could be used as a nutritional base to grow carotenoid-rich microbes.

Scaling up

In Nanjundaswamy's lab, scientists have proven they can successfully grow and extract naturally occurring pigments. But for this research to have an impact at a societal level, Nanjundaswamy is now working to scale up his research for commercial use.

In 2023, opened at the Research Park at SDSU. This state-of-the-art bioprocessing facility is precisely the space Nanjundaswamy needed to move his work from the lab to the marketplace. à£à£Ö±²¥Ðã BioWorx has a variety of bioreactors with capacity ranging from 30 to 3,000 liters and downstream processing equipment, that will allow Nanjundaswamy to produce large quantities of carotenoid-rich microbes.

These bioreactors will also allow Nanjundaswamy to gain a better understanding of the processes taking place inside production containers of different sizes.

"From an engineering point of view, what happens in a seven-liter flask will be totally different than what happens in a 3,000-liter bioreactor," Nanjundaswamy said. 

Last year, the researchers produced a 70-liter batch at à£à£Ö±²¥Ðã BioWorx, which provided them vital information on the processes and challenges in scaling up their work.

Currently, Nanjundaswamy and the research team are looking to acquire additional funding that will allow them to conduct scale-up feasibility studies.

"These studies will provide cost-benefit ratios and techno-economic analyses," Nanjundaswamy added.

Nanjundaswamy is studying a number of processes and conditions for his product development. They are trying to better understand product stability and suitable storage conditions as well as downstream processing. The team has even filed U.S. provisional patents on the processes and the end products they have developed.

"These are all very important in product development," Nanjundaswamy said. "These products have a lot of commercial potential."

Applications beyond food

Nanjundaswamy's research team is not solely focused on natural food coloring production. He started this work with the intention of using it in à£à£Ö±²¥Ðã feed and believes the same processes and products could be used to make naturally sourced color additives for à£à£Ö±²¥Ðã feeds.

Currently, the ban on synthetic dyes only applies to the food industry, but some believe the U.S. Department of Agriculture could ban synthetic dyes in à£à£Ö±²¥Ðã feed in the future.

Aside from food and à£à£Ö±²¥Ðã feed, Nanjundaswamy's products could potentially be used in personal care products.

Synthetic dyes currently make up roughly 70% of the color additive market. The forthcoming ban, and potential bans in other like industries, will open up the market for new products, like the ones Nanjundaswamy aims to produce. It's an especially exciting time for his lab as he believes he has a leg up on potential competitors in the market.

"I think we are way ahead of others," Nanjundaswamy said. "My lab has already optimized these material processes. Now it’s just a matter of scaling up."