Glutamic Acid: History and Discovery
In 1866 a German chemist boiled wheat flour paste in acid and watched unfamiliar crystals settle out — and so gave a name to one of the most important molecules in all of biology. That chemist was Karl Heinrich Ritthausen, the source was wheat gluten, and the new substance was named, quite literally, after the gluten it came from: glutamic acid. This article tells the documented story of that discovery and what came after: how an obscure crystal from flour turned out to be the savoury "fifth taste" that a Japanese professor named umami in 1908, how it became the seasoning the world knows as MSG, how soil bacteria were later harnessed to make it by the ton, and how, decades on, scientists recognised the very same molecule as the brain's chief excitatory messenger. Where the record is firm we say so; where a detail is uncertain or disputed, we mark it as such.
Table of Contents
- The Isolation: Ritthausen, 1866
- Where the Name Comes From
- The Age of the Amino Acids
- Ikeda and the Discovery of Umami (1908)
- From Laboratory to Larder: The Making of MSG
- Brewing an Amino Acid: The 1957 Fermentation Breakthrough
- The Brain's Messenger: Glutamate as a Neurotransmitter
- From Curiosity to Cornerstone
- Research Papers and References
- Connections
- Featured Videos
The Isolation: Ritthausen, 1866
The documented history of glutamic acid begins in 1866 with the German agricultural chemist Karl Heinrich Ritthausen (1826–1912). At the time of the discovery he was working at a German agricultural experiment station; he took up his well-known professorship of chemistry at the agricultural academy in Bonn (Poppelsdorf) the following year, in 1867. Ritthausen had devoted himself to the chemistry of plant proteins — a difficult, painstaking field in an era when the very idea of an "amino acid" was still taking shape. His method was the standard tool of the day: take a protein-rich material, break it down by boiling it in strong acid (he used sulfuric acid), and then sift through the resulting mixture for whatever crystallised out.
The material he worked with was wheat gluten — the stretchy, protein-rich substance left behind when the starch is washed out of wheat-flour dough. From the acid digestion of this gluten, Ritthausen obtained crystals of a previously unknown acid. He had isolated glutamic acid for the first time. The achievement is well attested in the history of chemistry, and Ritthausen went on to isolate a closely related compound, aspartic acid, a couple of years later, cementing his place as one of the founders of plant-protein chemistry.
It is worth pausing on how early this was. By the mid-1860s only a handful of the amino acids we now recognise as the building blocks of protein had been identified at all. Glutamic acid was a genuine addition to a very short list, and the techniques Ritthausen helped refine — hydrolysing proteins and analysing the fragments — became foundational to the whole science of biochemistry that followed. The crystals from a lump of wheat gluten were, in a real sense, a window into how proteins are built.
Where the Name Comes From
The name glutamic acid is one of the more transparent in all of chemistry: it was named directly after gluten, the wheat protein it was first extracted from. The word "gluten" itself comes from the Latin for "glue," a nod to the sticky, elastic character of the substance. So the lineage runs cleanly from the everyday word for the gluey part of dough, to the name of the molecule, to its ionised form — glutamate — which is the term most people meet today on a list of food ingredients or in a discussion of brain chemistry.
This naming-after-source was the convention of the era and connects glutamic acid to its chemical relatives. Aspartic acid, the compound Ritthausen isolated soon after, takes its name from asparagine, which had itself been named after asparagus, the plant it was first drawn from. Glutamine — the amide form of glutamic acid, and a major character in the molecule's later biological story — is named for its parent glutamic acid in turn. The naming is a small fossil record of where each molecule was first found: a flowering vegetable here, a lump of wheat gluten there.
A note on usage, because it can confuse newcomers. "Glutamic acid" and "glutamate" refer to essentially the same substance; glutamate is simply the form the molecule takes once it has shed a proton and gained a negative charge, which is how it exists at the pH of the body and of most foods. Throughout this article both terms appear, depending on context — "glutamic acid" for the isolated chemical and its history, "glutamate" for the active ionic form that carries the savoury taste and the nerve signal.
The Age of the Amino Acids
Ritthausen's discovery belongs to a remarkable century of chemical detective work in which, one by one, scientists pulled the individual amino acids out of proteins and gave them names. The story had opened in 1806, when the French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated asparagine from asparagus — the first amino acid ever obtained. Glycine followed in 1820, drawn from gelatin by Henri Braconnot, who called it "sugar of gelatin" for its sweet taste. Tyrosine was isolated from cheese by Justus von Liebig in 1846 and named from the Greek tyros, "cheese." Glutamic acid, arriving in 1866, took its place in this growing catalogue.
While the molecules were being collected, their collective identity was also being named. The word protein entered the language in 1838: the great Swedish chemist Jöns Jacob Berzelius proposed it to the Dutch chemist Gerardus Johannes Mulder, who used it in print that same year. It was coined from the Greek proteios, meaning "primary" or "of first importance" — a fitting label for the substances that turned out to be made of amino acids like Ritthausen's.
The era reached a kind of summit in 1902, when the German chemist Emil Fischer was awarded the Nobel Prize in Chemistry for his work on sugars and proteins. Fischer showed how amino acids link together through what is now called the peptide bond to form the long chains that make up proteins — the structural logic that explains why a protein such as gluten can be broken back down into individual amino acids like glutamic acid in the first place. (In a famous coincidence, Fischer and the chemist Franz Hofmeister independently described the peptide bond and presented their findings at the same meeting in Carlsbad in 1902.) Glutamic acid, isolated decades earlier, now had a theoretical home: it was one of the standard links in the protein chain.
Ikeda and the Discovery of Umami (1908)
For more than forty years after Ritthausen, glutamic acid was a chemist's curiosity. Then, in 1908, it became something far larger — the molecular explanation for a taste. The breakthrough came from Kikunae Ikeda, a professor of chemistry at Tokyo Imperial University. Ikeda was struck by a particular savoury, satisfying quality in dashi, the traditional Japanese stock made from kombu (the seaweed Laminaria japonica) and dried bonito. This taste, he reasoned, was distinct from the four then-recognised basic tastes of sweet, sour, salty, and bitter.
To find its source he did the patient work of a chemist. Starting from a large quantity of kombu — by the well-documented account, around 12 kilograms of dried kelp — he extracted and crystallised the substance responsible for the savoury taste, obtaining roughly 30 grams of it. The crystals proved to be glutamic acid, the very compound Ritthausen had pulled from wheat gluten in 1866. Ikeda gave the taste a name: umami, from the Japanese for "deliciousness." He published his findings in 1909 in a paper titled "New Seasonings" in the Journal of the Tokyo Chemical Society; an English translation appeared in the journal Chemical Senses in 2002 and remains the most accessible primary record of the discovery.
What Ikeda had recognised was that the salts of glutamic acid carry an intense, pure savoury taste, and that the sodium salt in particular dissolves readily and tastes best. This was more than a culinary observation. Umami is now accepted as a genuine fifth basic taste alongside the traditional four, with dedicated receptors on the tongue — a status that took most of the twentieth century to win full scientific acceptance, but whose origin point is firmly dated to Ikeda's 1908 work.
From Laboratory to Larder: The Making of MSG
Ikeda did not stop at identifying the molecule behind umami; he set out to make it usable in the kitchen. The most palatable, soluble form of the savoury substance was the sodium salt of glutamic acid — monosodium glutamate, or MSG. In 1908 Ikeda filed a patent for a method of producing this seasoning, and the following year, 1909, he joined with the businessman Saburōsuke Suzuki to bring it to market. Their product, the world's first commercial umami seasoning, was sold under the brand name Ajinomoto — Japanese for "essence of taste" — and the company of the same name still exists today.
The earliest MSG was made the hard way, by extracting glutamate from protein-rich materials such as wheat gluten or soybeans — the same kind of starting material, in effect, that Ritthausen had used in 1866, now turned to a commercial end. This extraction was laborious and the yields were modest, which kept the seasoning relatively costly in its first decades. The history of glutamic acid through the early twentieth century is in large part the history of finding cheaper, more abundant ways to obtain it.
It is on this same molecule that a long-running food-safety debate later played out. From the late 1960s, anecdotal reports linked MSG to a cluster of symptoms, and decades of argument followed about whether free glutamate added to food could cause harm. That controversy — and what the weight of modern evidence actually says — is a story about glutamate in the diet rather than about its discovery, and it is taken up on the companion MSG page and in the main Glutamic Acid article. Here it is enough to note that the additive at the centre of that debate is simply the sodium salt of the molecule Ritthausen first crystallised.
Brewing an Amino Acid: The 1957 Fermentation Breakthrough
The transformation of glutamic acid from a costly extract into a cheap, world-spanning commodity came in the 1950s, and it came from microbiology rather than chemistry. In 1957, a team of Japanese researchers led by Shukuo Kinoshita, with Shigezo Udaka and Masakazu Shimono, working at the Kyowa fermentation company, reported a discovery that changed the industry: they had found a soil bacterium that naturally secretes large amounts of glutamic acid. The organism was later named Corynebacterium glutamicum — the species name itself a tribute to the amino acid it pours out.
The idea was elegant. Rather than tearing glutamate out of expensive protein, one could simply feed sugar and a nitrogen source to a culture of these bacteria and let them manufacture the amino acid by fermentation, much as yeast makes alcohol. Kinoshita and his colleagues published their results in the Journal of General and Applied Microbiology, and commercial production by fermentation began almost immediately, in 1958. Within a few years this microbial route had largely displaced both acid extraction and chemical synthesis.
The significance of this step is hard to overstate, and it reaches well beyond MSG. Glutamic acid fermentation founded the entire field of industrial amino-acid production; the same bacterium and its descendants are now used to make several other amino acids on an enormous scale for food, animal feed, and medicine. The molecule that began as crystals from a chemist's flask in 1866 had become one of the highest-tonnage products of modern biotechnology — and it owed that scale to a humble soil microbe.
The Brain's Messenger: Glutamate as a Neurotransmitter
While food chemists and fermentation engineers were busy with glutamate's flavour and its manufacture, a separate line of inquiry was uncovering a wholly different role for the same molecule — this time inside the brain. From the late 1950s, researchers applying amino acids directly to nerve cells found that glutamate was a powerful excitant: it made neurons fire. Among the central figures were the physiologists David Curtis and Jeffrey Watkins, working with John Phillis in the laboratory of John Eccles in Australia, who from around 1959 showed that glutamate vigorously stimulated neurons throughout the nervous system.
For years this finding was met with deep scepticism. Glutamate was everywhere in the body and was known to be a workhorse of ordinary cellular metabolism, so the notion that it could also serve as a precise chemical signal between nerve cells struck many scientists as implausible — how could a molecule that common carry a specific message? It took decades of careful work, including the mapping of distinct glutamate receptors and the molecules that act on them, before the case became compelling. A landmark 1981 review by Jeffrey Watkins and Richard Evans is widely credited with pulling the evidence together and establishing glutamate as a bona fide neurotransmitter.
Today the conclusion is textbook: glutamate is the principal excitatory neurotransmitter of the vertebrate brain, carrying the great majority of fast excitatory signals and sitting at the heart of learning and memory. Its receptors — the NMDA, AMPA, and kainate channels among them — are central characters in modern neuroscience and in the search for treatments for epilepsy, stroke, chronic pain, and psychiatric illness. The mechanisms behind all of this are the subject of the main Glutamic Acid page; the historical point is simply how surprising it once was that the savoury crystal from kombu broth and the brain's busiest signalling molecule are one and the same substance.
From Curiosity to Cornerstone
Few molecules have travelled as far from their origins as glutamic acid. It entered the historical record in 1866 as nothing more than an unfamiliar crystal in a German chemist's acid digest of wheat gluten. A century and a half later it is, all at once, the savoury "fifth taste" of the world's cuisines, one of the largest-volume products of industrial fermentation, the master hub of nitrogen handling in the body's metabolism, and the chief excitatory signal of the brain. The same five-carbon molecule does all of this.
What ties the story together is a recurring pattern: a substance long used or encountered — in this case, the savoury depth of a good broth — turning out, on close investigation, to have a precise molecular identity, and that identity then opening doors no one expected. Ritthausen found the molecule; Ikeda found its taste and gave the world a seasoning; Kinoshita found a way to make it by the ton; Curtis, Watkins, and others found it hard at work in the brain. Each discovery was specific, dated, and the work of named people, and each revealed the same molecule in a new light.
That is the honest shape of glutamic acid's history: not a single eureka moment but a chain of them, spread across chemistry, food science, microbiology, and neuroscience, and stretching from a wheat-gluten flask in 1866 to the cutting edge of brain research today. The detailed biology — how glutamate signals, how the body makes and recycles it, what its dietary forms do — is covered in the companion Glutamic Acid Benefits articles and on the main page. This history is concerned only with how we came to know the molecule at all.
Research Papers and References
The list below gathers key primary and review sources for the history of glutamic acid alongside curated PubMed topic-search links. Author names, titles, and journals are given as plain text; only the stable DOI, PMID, or archive link is hyperlinked, and each opens in a new tab. Karl Heinrich Ritthausen's original 1866 isolation predates the modern indexed literature and is described in the article from the historical and biographical record rather than cited as a retrievable paper.
- Ikeda K. New seasonings. Chemical Senses. 2002;27(9):847-849. (English translation of the original 1909 paper reporting the discovery of umami and the identification of glutamate as its source.) — doi:10.1093/chemse/27.9.847 · PMID: 12438213
- Kinoshita S, Udaka S, Shimono M. Studies on the amino acid fermentation. Part 1. Production of L-glutamic acid by various microorganisms. Journal of General and Applied Microbiology. 1957;3(3):193-205. (The report of glutamate-secreting soil bacteria that launched industrial amino-acid fermentation; the classic paper was later reprinted in the same journal in 2004, 50(6):331-43, indexed as PMID 15965888.) — doi:10.2323/jgam.3.193
- Watkins JC, Jane DE. The glutamate story. British Journal of Pharmacology. 2006;147(Suppl 1):S100-S108. (A first-hand history of the recognition of glutamate as the brain's principal excitatory neurotransmitter.) — doi:10.1038/sj.bjp.0706444 · PMID: 16402093
- Glutamic acid — history, isolation, and discovery — PubMed: glutamic acid history and discovery
- Umami, glutamate, and the discovery of the fifth taste — PubMed: umami and glutamate history