Making colors is not easy. Actually, seeing colors isn't easy either - most creatures don't see the rainbow the way we do. There's even plenty of humans who can't "see" certain colors, blue being the last to be recognized and named in most cultures (if this is the first time you're hearing about this, just search this site with the term "color" and learn more).
Colors are not easy to make, not by nature and certainly not by humans. If a tree, for example, makes a vibrant, jewelescent red color, it might be bright, but it won't last long. To make a color that's strong but that also lasts a long time, it usually takes either a lot of effort, or a lot of toxic materials, and usually both. Tyrian purple? Not easy. Fire engine red? Toxic.
But once in a while, we figure out a way to break those rules, because humans are pretty good at that, in fact, it's kind of one of the things we do best.
Nature's palette reinvented: New fermentation breakthrough in sustainable food coloring
Dec 2023, phys.org
It's a fermentation process that produces "betalain-type" food colors (betalanins give red beets their distinctive bright pinkish red color).They used an oleaginous yeast Yarrowia lipolytica found in cheese, then performed metabolic engineering to optimize the cellular metabolism.
via Danmarks Tekniske Universitet Novo Nordisk Foundation Center for Biosustainability DTU Biosustain: Philip Tinggaard Thomsen et al, Beet red food colourant can be produced more sustainably with engineered Yarrowia lipolytica, Nature Microbiology (2023). DOI: 10.1038/s41564-023-01517-5
Totally unrelated image credit: AI Art - Holographic Pill Advertisement - 2024
Chemists create organic molecules in a rainbow of colors that could be useful as organic light-emitting diodes
Dec 2023, phys.org
Acenes are chains of benzene molecules that have unique optoelectronic properties for use as semiconductors, and can also be tuned to emit different colors of light. These researchers dope acenes with boron and nitrogen for better properties, but also add the ligand carbodicarbene to improve stability.
via MIT: Chun-Lin Deng et al, Air- and photo-stable luminescent carbodicarbene-azaboraacenium ions, Nature Chemistry (2023). DOI: 10.1038/s41557-023-01381-0
What makes urine yellow? Scientists discover the enzyme responsible
Jan 2024, phys.org
When red blood cells degrade after their six-month lifespan, a bright orange pigment called bilirubin is produced as a byproduct, and is secreted into the gut. "Gut microbes encode the enzyme bilirubin reductase that converts bilirubin into a colorless byproduct called urobilinogen. Urobilinogen then spontaneously degrades into a molecule called urobilin, which is responsible for the yellow color we are all familiar with."
via University of Maryland: BilR is a gut microbial enzyme that reduces bilirubin to urobilinogen, Nature Microbiology (2024). DOI: 10.1038/s41564-023-01549-x
Beetles living in the dark teach us how to make sustainable colors
Mar 2024, phys.org
Chitin, or insect exoskeleton, is Earth's second most abundant organic molecule, and is already approved for medical use.
They created the color by manipulating the folding patterns of the structure, so this is a structural color approach as opposed to a dye or pigment.
via Singapore University of Technology and Design: Akshayakumar Kompa et al, Large‐Scale Artificial Production of Coleoptera Cuticle Iridescence and Its Use in Conformal Biodegradable Coatings, Advanced Engineering Materials (2024). DOI: 10.1002/adem.202301713
Researchers advance pigment chemistry with moon-inspired reddish magentas
Apr 2024, phys.org
RED!
From the makers of YInMn blue who mixed black manganese oxide with other chemicals, then heated them in a furnace to nearly 2,400 degrees Fahrenheit.The new pigments, which could be used as energy-efficient coatings for vehicles and buildings, are based on divalent chromium, Cr2+, and are the first to use it as a chromophore; chromophores are the parts of a molecule that determine color by reflecting some wavelengths of light while absorbing others.Inspired by the divalent copper that serves as a chromophore in Egyptian blue, they replaced the divalent copper with divalent chromium, leading to durable, reddish magenta pigments.BTW - "Most of the magenta-colored pigments used today are organic chemicals and suffer from stability issues when exposed to ultraviolet rays and heat from the sun because they can break down organic chemical bonds. Inorganic magenta pigments are rare, and most require a significant amount of cobalt salts that are hazardous to both humans and the environment."
via Oregon State University: Anjali Verma et al, Cr2+ in Square Planar Coordination: Durable and Intense Magenta Pigments Inspired by Lunar Mineralogy, Chemistry of Materials (2024). DOI: 10.1021/acs.chemmater.4c00253
Post Script:
The role of history in how efficient color names evolve
Mar 2024, phys.org
The past color vocabulary of a language shapes its ability to evolve."Once you as a linguistic community have an efficient vocabulary, that starting point restricts the next possible efficient vocabulary that you could have when you introduce a new term," says Twomey, the first author. "As the vocabulary grows, the number of different vocabularies that you could move to is increasingly constrained."
(I call this the 'chips vs crisps' phenomenon)
They used Berlin and Kayes World Color Survey - 25 speakers from each of 110 languages asked to name the same set of 330 color stimuli.
- Green-blue and blue are quite susceptible to changes in meaning as new terms are added, whereas red, black, and yellow remain relatively stable in meaning.
- A historical vocabulary would most likely split green-blue into separate terms whereas the de novo vocabulary is more likely to introduce light green or orange than pink.
- In principle, we can infer what ancestral color vocabularies were and then compare that to the historical record.
- An example he provides is that at certain points in history, certain commercial dyes were introduced that became economically important to a culture.
via University of Pennsylvania: Colin R. Twomey et al, History constrains the evolution of efficient color naming, enabling historical inference, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2313603121
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