indigo

Safer Ways To Be Blue | Earth Wise

May 5, 2020 By EarthWise Leave a Comment

Creating blue fabric has always been desirable for people. It has never been easy, but the original way to do it – by using indigo from plants – has been around for 6,000 years. Natural indigo is a rare commodity, often referred to as blue gold. In the 19th century, synthetic indigo was developed and ultimately replaced the natural substance.

Synthetic indigo dye is not an environmentally friendly substance. In order to get it to adhere to fabrics, substances called mordants are required. These are commonly made from metals like chromium and aluminum, are generally toxic, and kill off plants exposed to factory wastewater, destroy ecosystems, and poison drinking water. The dye itself is slow to decompose and is bad for the environment.

Recently, an organic chemist in Brazil named Erick Bastos has figured out a new way to produce blue dye using, of all things, a pigment from beets. By extracting the pigment and tweaking its molecular pattern, he has managed to transform the red color of the pigment to a brilliant blue.

Beet roots contain pigments called betalains and just a tiny amount of beetroot juice can render a lot of dye. By mixing these pigments with a couple of ingredients, a chemical reaction occurred, and the color transformed from red, to yellow, then green, and finally blue.

Testing so far on human liver cells, retinal cells, and developing zebrafish has revealed no toxicity. The results suggest that the new dye – dubbed BeetBlue – is safe. Further testing is needed to know if it is truly safe and whether it will last in the wash. Meanwhile, Professor Bastos is not patenting the dye and hopes it will provide a better way to be blue.

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How Do You Make a Less Toxic Blue Dye? Start With Red Beets

Photo, posted November 7, 2005, courtesy of Lain Buchanan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Green Way To Turn Blue

August 5, 2019 By EarthWise Leave a Comment

Indigo dye is what is used to color denim cloth and blue jeans. Historically, the dye came from a tropical plant most often found on the Indian subcontinent. Eventually, it became economically favorable to synthesize the dye instead and almost all of the 50,000 tons of the dye used annually is synthetic.

The processes used to make synthetic indigo are efficient and inexpensive, but they often require toxic chemicals and create a lot of dangerous waste. Researchers at the Department of Energy’s Joint BioEnergy Institute have now developed an eco-friendly production platform for a blue pigment called indigoidine. It has a similarly vividly saturated blue hue as synthetic indigo.

The researchers were investigating the ability of various fungal strains to express large enzymes known as NRPSs. They chose an NRPS that converts two amino acid molecules into indigoidine – a blue pigment – in order to make it easy to tell if the strain engineering had worked. Having the culture turn blue was an effective indicator.

Their primary interest was not the pigment but when they saw just how blue the culture was for one particular fungus, they realized that the fungal strain did not just produce indigoidine; it produced large amounts of it.

Thus they have found a way to efficiently produce a blue pigment that uses inexpensive, sustainable carbon sources instead of harsh chemicals. There is already a great deal of interest from the textile industry, where many companies are eager for more sustainably sourced pigments because customers are increasingly aware of the impacts of conventional dyes.

Thanks to a talented fungus called Rhodosporidium toruloides, there may now be a green way to turn blue.

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Blue Pigment from Engineered Fungi Could Help Turn the Textile Industry Green

Photo, posted March 7, 2006, courtesy of Willi Heidelbach via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.