Chapter 12.08: The Erythorbate Letter

Introduction to Bacon & the Art of Living

The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting.  Modern people interact with old historical figures with all the historical and cultural bias that goes with this.


The Erythorbate Letter
Cape Town, November 1959

Dear Tristan,

Bacon stretches your mind. The curing brine and meat are two complex environments and adding them together increase the complexity level much further. When I set out on my quest I very early on learned that I have to understand the chemistry of curing and of proteins.

Learning this has given me endless pleasure over the years. I enjoy the predictability of its processes. We finally advance to one of the last ingredients used in bacon curing. Functionally, it is an anti-oxidant, called erythorbate (not to be confused with erthro- which refers to the colour red, as in, erytrozene).

Proper bacon.jpg

Proper Bacon, produced and photographed by Robert Goodrick. An example of a good cut and excellent curing. His technique with this batch of bacon was dry curing, 4 days before a quick rinse and hung to equalize for close to two weeks. No vacuum bags, meat lugs and open. Temperature is 2 C.

INTRODUCTION

In meat curing, sodium erythorbate [E316] (C6H7NaO6) functions as an antioxidant, to increase the rate of nitrite reduction to nitric oxide which reduces the amount of residual nitrite in cured meat after curing sufficiently took place. In the modern curing plant, speeding up the formation of nitric oxide from nitrite is important because it speeds up the curing time but far more important than this, it reduces the nitrite levels left in the meat after curing. Nitrite itself, at the minuscule levels used in meat curing, is not dangerous to human health, but “unreacted” nitrite forms n-nitrosamines during frying and in the stomick which have been linked to the development of various cancers. The meat industry responded to this by including either ascorbate (Vitamin C) or erythorbate in curing mixes as anti-oxidants. Including either ascorbate or erythorbate in bacon is one of the ways that bacon is changed into safe food. (1) (see Regulations of Nitrate and Nitrite post-1920: the problem of residual nitrite)

Ascorbic acid and erythorbate have been widely used in recent years to improve the colour of cured meats. Watts and Lehman (1952a) found that 0.1 percent of ascorbic acid added to meats caused better colour development when the meat was heated at 70°C. or frozen at -17°C. These workers (1952b) observed that haemoglobin did not react with ascorbic acid in the absence of oxygen. Ascorbic acid reduced methemoglobin and promoted the reduction of nitrite to nitric oxide. In the presence of oxygen, an undesirable side reaction occurred in which the green pigment choleglobin was formed. According to Hollerbeck and Monahan (1953), the beneficial effect of ascorbic acid in curing meat is due to the reduction of nitrogen dioxide to nitric oxide. Kelley and Watts (1957) observed that cysteine, ascorbic acid, and glutathione were capable of promoting the formation of nitric oxide hemoglobin, regenerating this pigment on surfaces of faded meat and protecting surfaces of cured meat from fading when exposed to light.” (Cole, 1961) (Reaction Sequence)

Erythorbate is far less expensive than ascorbate, making this a favourite for inclusion in curing brines and accounts for its widespread use. Chemically, erythorbic acid’s sodium salt is sodium erythorbate. I use erythorbate in this letter to refer to either one of the two forms.

Erythorbic acid is a stereoisomer of ascorbic acid (vitamin C), meaning that the two compounds differ only in the spatial arrangement of their atoms. Previously it was called isoascorbic acid, D-araboascorbic acid. (Walker, R)

I wondered where and how this compound was discovered and if it occurs naturally.

ANTI-SCORBUTICS

The isolation and identification of vitamin C or ascorbic acid at the beginning of the 1930s was a big deal. It solved the riddle of the anti-scurvy agent which eluded humans for centuries (see Concerning the Discovery of Ascorbate) and after its identification, science moved to learn everything there was about it. The most urgent question now became its synthesis which allows it to be produced in massive quantities, in the cheapest possible way.

The priority was justified. Scurvy was a widespread, universal problem, not just for the navy. Notes by Tamango Ltd., On the prevention of scurvy among native workers; Oranges and Orange Juice, published in May 1936 deals with the prevalence of scurvy among the native population and its impact on industries like gold and diamond mining in the Free State, Gauteng and Northern Cape and the sugarcane industry in Natal. It deals with scurvy and it’s widespread occurrence among native school children. It offered as a solution to vitamin C deficiency which, according to the authors, hampered the growth of the economy of the Union of South Africa. It takes aim at the mass production of citrus fruit and suggests that instead of exporting it all, to make this available for industry to feed its workforce.

Apart from being highly informative on another subject of great interest to me namely the traditional diets of native populations across the world and the negative impact of colonization on these societies, it highlights the priority that vitamin C had in our world in the late 1800s and early 1900s in the context of finding the best and cheapest available source for it, especially after its isolation and identification in the early 1930s. (2)

ARABO-ASCORBIC ACID OR ERYTHORBIC ACID

In 1933 and 1934, researchers showcased synthesised d and l-ascorbic acid and prepared synthetic analogues. One of these they called arabo-ascorbic acid (from arabinosone). The product was synthetically derived from an osone (an osone is a compound that contains two alpha carbonyl groups and is obtained by hydrolyzing an osone). (Ault, 1933 and Baird, 1934) The reason for their work has been a well-established method by this time in the development of new pharmaceutical medicines. According to this method, an initial compound is identified (referred to as the lead compound). This compound possesses the activity of interest. Such an activity of interest may exist in the particular compound along with some undesirable characteristics such as toxicity, unsuitable half-life or poor availability (in vivo). A process is then embarked on to develop and analyze analogues of such a lead compound and to evaluate their different characteristics. (Gutte, B.. (Ed); 1995: 396)

It seems that it was the German chemists, Kurt Maurer and Bruno Schiedt who, in August 1933, were the first researchers to have synthesized erythorbic acid. (Maurer and Schiedt, 1933) It is estimated to be only one-twentieth as effective as ascorbic acid (Daniel and Munsell; 1937: 6) and is not capable of preventing scurvy but it nevertheless possesses great oxygen reducing characteristics which makes it ideal for industrial application due to its ease of production.

The researchers Takahashi, T., et al. became the first to report on the production of D-araboascorbic acid from penicillin. This was important since it showed that erythorbate was indeed a naturally occurring product. They refer to Isherwood, et al. who also found it in cress seedling in D-altrono-r-lactone solution and in the urine of rats injected with D-mannono-r-lactone.

A strain of Penicillium which they isolated from soil produced D-araboascorbic acid (erythorbic acid) from D-glucose, D-gluconic acid and sucrose. (Takahashi, T., et al. 1960) Today it is synthesized by a reaction between methyl 2-keto-D-gluconate and sodium methoxide. The method of synthesizing it from sucrose or by strains of Penicillium are still in use.

The exact meaning of the prefix “erythor” eludes me and there is no connection with the similar-sounding prefix, “erythro” meaning red which would be a tidy connection with meat curing, but several sources refute this.

Dr. R. Walker, Professor of Food Science, Department of Biochemistry, University of Surrey, England, offers the following information: “Erythorbic acid (syn: isoascorbic acid, D-araboascorbic acid) is a stereoisomer of ascorbic acid and has similar technological applications as a water-soluble antioxidant. This compound was previously evaluated under the name isoascorbic acid; at the last evaluation an ADI of 0-5 mg/kg b.w. was allocated, based on a long-term study in rats, and a toxicological monograph was prepared. The name was changed to erythorbic acid in accordance with the “Guidelines for designating titles for specifications monographs.” (Dr. R. Walker)

Finally

This is only a brief introduction. In my experience, there is little difference in curing time between the use of erythorbate or ascorbate and the price difference is material. I have noticed that some producers include a mixture of both compounds in their brine preparations. Another aspect of great interest is its characteristic as a potent enhancer of nonheme-iron absorption. This is, however, again, outside the realm of meat curing and will have to happen in a different format.

My son!! I am seeing you next month! Wow! When I travelled the world, did you guys ever miss me this much! Minette and I are planning a trip to Nepal next year. Let us know if you want to join us! I would love La to also come along, but she may not be able to get leave.

I’m counting the days!

Lots of love from Cape Town,

Dad and Minette


Further Reading

Erythorbate


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Notes

  1. The other ways in which this has been accomplished over the years are to restrict the amount of nitrite allowed in curing and to prevent the simultaneous use of nitrite and nitrate in meat such as bacon with are produced using relatively short curing times. (see Regulations of Nitrate and Nitrite post-1920: the problem of residual nitrite)
  2. The document from Wits mentions Pryde (1931) who quotes Herbert Spencer’s “ Study of Sociology (1880) ” concerning the early use of Citrus juices for the cure of scurvy:— “ It was in 1593 that sour juices were first recommended by Albertus, and in the same year Sir R. Hawkins cured his crew of scurvy by lemon-juice. In 1600, Commodore Lancaster, who took out the first squadron of the East India Company’s ships, kept the crew of his own ship in perfect health by lemon-juice, while the crews of the accompanying ships were so disabled that he had to send his own men on board to set sails. In 1636, this remedy was again recommended in medical works on scurvy. Admiral Wagner, commanding our fleet in the Baltic in 1726, once more showed it to be specific. John Woodall, in 1628, used lemon-juice for the treatment of scurvy, and gave a full description in his ‘ Viaticum, being the Pathway to the Surgeon’s Chest’ (1628). “ The virtues of orange juice for scurvy dates back to 1671 when Venette, considered orange and lemon juice contained ‘ something which was directly opposed to the causes of scurvy,’ cited by Browning (1931). ‘ Vitamins’: Special Report Series No. 167 (1932): Medical Research Council, London, contains an interesting account of the experience of Lind (1747). Lind had twelve scurvy patients on his hands-on board the “Salisbury” at sea, on the 20th of May, 1747. ‘ They all, in general, had putrid gums, the spots, and lassitude, with weakness of the knees ………….and had one diet common to all, viz., water-gruel sweetened with sugar in the morning, fresh mutton-broth often times for dinner, at other times light-puddings, boiled biscuit, and sugar, etc., and for supper barley and raisins, rice and currants, sago and wine or the like.’ Lind treated two each of his patients with (1) cyder, (2) elixir vitriol, (3) vinegar, (4) sea-water, (5) an electary composed of garlic, mustard seed, radaphan, balsam of Peru, and gum myrrh, and (6) ‘two oranges and one lemon given them every day.’ Supplies of oranges and lemons lasted for six days. ‘ The consequence was, that the most sudden and visible good effects were perceived from the use of oranges and lemons; one of those who had taken them being at the end of six days fit for duty. The spots were not indeed quite off his body, nor his gums sound; but, without any other medicine, than a gargarism of elixir vitriol, he became quite healthy before we came to Plymouth, which was on the 16th June. The other (on the orange and lemon ration) was the best recovered of any in his position, and, being deemed pretty well, was appointed nurse to the rest of the sick.’ ” (historicalpapers.wits.ac.za)Since these early days of scurvy on land and sea, the juice of Citrus fruits has been always regarded as the more efficacious remedy, and modern science confirming their merits as the best and cheapest of anti-scorbutics. At sea, today, by an Order in Council (Statutory Rules and Orders, 1927, Merchant Shipping), provision is made for the issue of orange juice—concentrated orange juice containing not less than 70% of total solids—at the rate of I f fl. ozs. mixed with six times its volume of water.” (historicalpapers.wits.ac.za)

References

Ault, R. G., Baird, D. K., Carrington, H. C., Haworth, W. N., Herbert, R., Hirst, E. L., Percival,

E. G. V., Smith, F. and Stacey, M.. 1933. Synthesis of d– and of l-ascorbic acid and of analogous substances. J. Chem. Soc., 1933, 1419- 423, http://dx.doi.org/10.1039/JR9330001419

Baird, D. K., Haworth, W. N., Herbert, R. W., Hirst, E. L., Smith, F. and Stacey, M.. Ascorbic acid and synthetic analogues. J. Chem. Soc., 1934, 62-67, http://dx.doi.org/10.1039/JR9340000062.

Daniel, E. P., Munsell, H. E.. 1937. Vitamin Content of Foods. United States Department of Agriculture.

Gutte, B.. (Ed) 1995. Peptides: Synthesis, Structures, and Applications. Academic Press.
Maurer, K. and Bruno Schiedt, B.. (August 2, 1933) “Die Darstellung einer Säure C6H8O6 aus Glucose, die in ihrer Reduktionskraft der Ascorbinsäure gleicht (Vorläuf. Mitteil.)” (The preparation of an acid C6H8O6 from glucose, which equals ascorbic acid in its reducing power (preliminary report)), Berichte der deutschen chemischen Gesellschaft, 66 (8): 1054-1057. (http://onlinelibrary.wiley.com/doi/10.1002/cber.19330660807/pdf)

Maurer, K. and Schiedt, B.. (July 4, 1934) “Zur Darstellung des Iso-Vitamins C (d-Arabo-ascorbinsäure) (II. Mitteil.)” (On the preparation of iso-vitamin C (d-arabo-ascorbic acid) (2nd report)), Berichte der deutschen chemischen Gesellschaft, 67 (7) : 1239–1241

Takahashi, T., Mitsumoto, M. and Kayahori, H.. 1960. Production of D-Araboascorbic Acid by Penicillium. Nature volume188, pages411–412 (29 October 1960)

Takahashi, T., Mitsumoto, M. and Kayahori, H.. 1960. The Production of D-Araboascorbic Acid by a Mold. Bull. Agr. Chem. Soc. Japan, Vol. 24, No. 5, p. 533 – 534, 1960.

Dr R. Walker, Professor of Food Science, Department of Biochemistry, University of Surrey, England.

Chapter 12.07: The Ascorbate-Letter

Introduction to Bacon & the Art of Living

The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting.  Modern people interact with old historical figures with all the historical and cultural bias that goes with this.


The Ascorbate Letter

Cape Town, November 1959

Tristan,

A few more weeks and you and La are here. We can hardly wait! There is so much to discuss! I remember when I rode transport that when I leave for the Rand, my dad used to ride out with me and upon my return, he will get word of our approach and would meet up with me on the other side of Worcester. He would always say to me after our greetings, “Let’s ride home together and you start telling me everything. Don’t skip a thing!” He was always so proud of my many stories and when we visit Unce Jacobus, my dad would tell him my adventures as if I am not even there. I now understand it! Come prepared to tell me everything! I can’t wait to hear what your life is like!

After many years I finally progressed in the grand story of bacon; a quest to understand it and cure the finest bacon anywhere on our planet; we progressed to the last essential ingredient namely an anti-oxidant. Of all the many stories of bacon, the discovery of ascorbate or Vitamin C is one of the most colourful.

Background

Repetition aids learning. Let us again review elements of what I have written to you and your sister about. Nitric oxide, a derivative from nitrite, reacts with an active group in the muscle tissue, to create the cured meat colour. It plays a further role as an antimicrobial agent and is partly responsible for the cured meat taste. This makes nitrite along with salt (sodium chloride) the most important curing agents.

The other key ingredient for bacon cures is ascorbate or vitamin C. Either as sodium ascorbate or ascorbic acid or its isomer, erythorbate, either as erythorbic acid or its salt, sodium erythorbate. The functional value of ascorbate is significant. (1)

The Function of Ascorbate in Bacon Curing.

There are at least four benefits in using ascorbate in meat curing.

a. Ascorbate or its isomer, erythorbate was originally used to speed up cured meat colour formation. (Pearson, A. M. and Tauber, F. W.; 1984: 53) It achieves this apparently by reducing the brown meat pigment, metmyoglobin to myoglobin with its purple-red colour. (Chichester, C. O.; 1984: 14)

b. “Ascorbate reacts chemically with nitrite to increase the yield of nitric oxide from nitrous acid. Nitric Oxide is responsible for meat curing.” (Pearson, A. M. and Tauber, F. W.; 1984: 53) It therefore also reduces the level of “residual nitrites” which is important in preventing the formation of N-Nitrosamines.  This is a key tool in the worldwide strategy to ensure that bacon remains a safe product to eat.

c. “Excess ascorbate acts as an antioxidant, thereby stabilising both colour and flavour. It prevents rancidity and the fading of sliced bacon when exposed to light. It achieves this through the prevention of heme-catalyzed lipid oxidation which results in both pigment degradation and rancidity. As long as excess ascorbate is present, the pigments are protected against breakdown. (Pearson, A. M. and Tauber, F. W.; 1984: 53)

d. Under certain conditions, ascorbate has been shown to reduce nitrosamine formation. (Pearson, A. M. and Tauber, F. W.; 1984: 53)

Only sodium ascorbate or sodium erythorbate (as opposed to ascorbic acid and erythrobic acid) are used in meat cures since ascorbic and erythorbic acid reacts with nitrite to form nitrous oxide. Nitrous Oxide is dangerous in confined spaces and its formation reduces the amount of nitrite available to participate in meat curing. (Pearson, A. M. and Tauber, F. W.; 1984: 53)

The value of nitrite has been discovered over the last 200 years. (2) Previous articles dealt with its recognition as a curing agent and how the curing industry ended up using it. (3) We now turn our attention to ascorbate. We first look at its discovery.

The Discovery of Vitamins

casimir

The Polish biochemist, Kazimierz Funk (1884 – 1967) or, in English, Casimir Funk.

The term “vitamin” was coined by Casimir Funk in 1912 while working at the Lister Institute of Preventive Medicine, in London. It is a combination of the words, “vital” and “amine” meaning the “amine of life”. In 1912, it was believed that “accessory factors” (9) in some foods, necessary for the function of the human body, prevented certain diseases like beriberi and scurvy.

It was thought that these “accessory factors” might be chemical amines. It turned out that this is the case with thiamine (vitamin B1), but after it was found that other such micronutrients were not amines, the word was shortened to vitamin in English.

The discovery of vitamins happened at a time when the prevailing theory of disease was the germ theory and “dogma held that only four nutritional factors were essential namely proteins, carbohydrates, fats, and minerals.” It was however recognised in this time, by clinicians that scurvy, beriberi, rickets, pellagra, and xerophthalmia were “specific vitamin deficiencies, rather than diseases due to infections or toxins .” (Semba RD; 2012: 1) The period when the vitamins were discovered stretches from the early 1800s until the mid-1900s. (Semba RD; 2012: 1)

The discovery of the individual vitamins was not the result of big eureka moments but the fruit of the labour and contributions of many epidemiologists, physicians, physiologists, and chemists, from around the world. Like many discoveries, “it was slow, stepwise progress that included setbacks, contradictions, refutations, and some chicanery.” (Semba RD; 2012: 1) I don’t wish to give you an exhaustive account of the story of its discovery with every important contributor and contribution listed. It is an overview and a general introduction to some of the main characters in the great saga of the discovery of Vitamin C.

The Discovery of Ascorbate or Vitamin C

Dr Albert Szent-Gyorgyi2

Hungarian scientist Albert von Szent-Györgyi, recipient of the 1937 Nobel Prize in physiology or medicine, “for his discoveries in connection with the biological combustion processes, with special reference to vitamin C and the catalysis of fumaric acid.”

The intense scientific inquiry into possible cures and preventative methods for scurvy began at the beginning of the 1800s with the work of George Budd (1808-82), Professor of Medicine at King’s College, London. (Hughes, R. E.; 2000) “In 1842, Budd published in the London Medical Gazette a series of articles entitled, “Disorders Resulting from Defective Nutriment.” He described “three different forms of disease which are already traced to defective nutriment” and argued that such conditions resulted from the absence of dietary factor(s) other than carbohydrate, fat, and protein and that the absence of each of these specific factors would be associated with a specific disease. This idea lay dormant for 40 years until it was experimentally proved by N. Lunin. (Hughes, R. E.; 2000)

L. J. Harris who himself made significant contributions in the later story of vitamin C, referred to Budd as “the prophet Budd” and cited an article where Budd expressed the belief that scurvy was due to the “lack of an essential element which it is hardly too sanguine to state will be discovered by organic chemistry or the experiments of physiologists in a not too distant future” (Hughes, R. E.; 2000)

Little happened, however, to fulfil Budd’s prophecy until the beginning of the twentieth century with the work of A. Holst and T. Fröhlich of Norway. ((Hughes, 2000) and (McCollum, 1922)) They observed that for growth and “prolonged well-being” in rats, the following was necessary: “A single purified protein, a source of the sugar glucose, nine mineral elements and two uncharacterized dietary factors” (McCollum, E. V.; 1922: 365) The two unknown dietary factors he called “A” and “B”.

It seemed natural for the scientific community to call the antiscorbutic factor they were looking for, “accessory food factor C.” The phrase was however clumsy and people already got used to the term vitamine. After chemists made peace with the option of dropping the e and thereby not referring to any particular chemical structure, the antiscorbutic factor was called vitamin C.

Zilva, working in the Biochemistry Department at the Lister Institute, London was leading the way and he attempted to isolate it from lemon juice. He was able to create a solution that contained Vitamin C (the presence of which was confirmed in tests on babies) with the citric acid being removed, but as soon as it was evaporated to dryness, the functionality disappeared. (Carpenter, J. K.; 1986: 187)

Tillmans and Hirsch

The search for Vitamin C continued with renewed vigour until the 1930’s when two different approaches both lead to the discovery of Vitamin C. (Daniel E. P. and Munsell H. E; 1937: 5) The concentration of Vitamin C, derived from lemon juice was studied in depth over a long period of time. Two German chemists, J. Tillmans and P. Hirsch (1927) observed that there is a correlation between the reducing capacity of plants and animal tissue and their Vitamin C content. (4) (Daniel E. P. and Munsell H. E; 1937: 5)

Biological oxidation-reduction systems were also being studied where a strong reducing substance was identified with the empirical formula of CodeCogsEqn (18) from the adrenal cortex. (5) The substance was acidic and resembled the carbohydrates in reducing power and colour reactions. (Daniel E. P. and Munsell H. E; 1937: 5)

Albert Szent-Györgyi

Parallel to this work was that of Dr. Albert Szent-Györgyi’s who isolated hexuronic acid. The work of Dr. Szent-Györgyi became legendary. Dr. Szent-Györgyi, “a Hungarian biochemist, was working on plant respiration systems at Groningen in Holland and became interested in a reducing compound present in his preparations.” (Hughes, R. E.; 2000)

F. G. Hopkins, himself a valuable contributor to the work on vitamins (he demonstrated in 1912 the presence of growth factors in milk and showed their essential dietary nature) invited Szent-Györgyi to Cambridge to extend his studies. In 1927, Szent-Györgyi isolated his “Groningen reducing agent” in a crystalline, from oranges, lemons, cabbages, and adrenal glands.” (Hughes, R. E.; 2000)

He published his discovery in 1928, and after some struggle to find an appropriate name, called this new substance hexuronic acid. In this paper, a statement is made about the studies on the reducing substances of lemon juice, and mentioned that they “established interesting relationships between vitamin C and the reducing properties of plant juices.” (Daniel E. P. and Munsell H. E; 1937: 5)

McKinnis, King, and Svirbely

In 1930 R. B. McKinnis and C. G. King, a vitamin researcher at the University of Pittsburgh, suggested in a publication that hexuronic acid could be vitamin C. (Halver J. E., and Scrimshaw, S.; 2006: 5, 6) The work of King and Szent-Györgyi would find an interesting and controversial link in the person of J. L. Svirbely who previously worked with King and was appointed by Szent-Györgyi to assist him, in 1931.

While still at Cambridge, Szent-Györgyi was approached by the Hungarian minister of education, Count Kuno Klebelsberg, who wanted to rebuild the Hungarian scientific institutions with Rockefeller Foundation support for expanding the programs in Szeged. He was invited to return to Hungary and chair the medical chemistry department at the University of Szeged. (The Albert Szent-Györgyi Papers) With limited advancement opportunities at Cambridge, he took up the new position in January 1931.

Szent-Györgyi was an eccentric, informal, unorthodox, brilliant and very popular professor and a thorn in the flesh for many more conservative colleagues. Apart from fascinating lectures, he was known for “dining or playing sports with his students, riding his bicycle to visit colleagues (as was common at Cambridge)–but the students loved him for his free and spontaneous approach to education.” (The Albert Szent-Györgyi Papers)

Within the first six months in Szeged, he had done in terms of educational vigour and introducing educational programs and research structures, more than many people do in their lifetime. (The Albert Szent-Györgyi Papers) Towards the end of 1931, an American post-doctoral fellow, Joseph Svirbely, also a Hungarian native, joined Szent-Györgyi’s research team at the invitation of Szent-Györgyi. (The Albert Szent-Györgyi Papers) Together they conducted landmark experiments on guinea pigs, “which, like humans must ingest Vitamin C to maintain health since they also cannot produce it within their bodies. These experiments showed that “hexuronic acid — renamed ascorbic acid to reflect its anti-scurvy properties — was indeed the long-sought vitamin C.” (Schultz, J.; 2002)

Controversy

The discovery has not been without controversy. Who exactly discovered it first? Was it Szent-Györgyi or another researcher who would claim this, Glen King? Central to the controversy is Joseph Svirbely. This is how it unfolded.

J. L. Svirbely initially worked with C. G. King at the University of Pittsburgh, trying to isolate vitamin C, along with graduate students H. L. Sipple, O. Bessie, F. L. Smith, and W. A. Waugh. “They were able to prepare vitamin C concentrates from lemon juice and studied the properties of vitamin C fractions from 1929 to 1931. Otto Bessie, from Montana, did not trust J. L. Svirbely.” It is reported that on one occasion their disagreements ended in physical blows. (Halver J. E., and Scrimshaw, S.; 2006: 5, 6)

Svirbely completed his work in Pittsburgh under King and was awarded his Ph.D.. He received a postdoctoral fellowship to work in Germany under Professor H. Wieland. In the fall of 1931, he changed his plans and went to Hungary when Szent-Györgyi offered him an appointment in Hungary which he was keen to take up. (Jukes, T.; 1988: 1290) This was a strategic appointment by Szent-Györgyi. One that was fully within his right to do and a lesson in how key appointments can swing the course of events in one’s favour.

Svirbely came with all the experience he gained from working with King. Szent-Györgyi later admitted this himself when he wrote, “When I asked him (Svirbely) what he knew he said he could find out whether a substance contained vitamin C. I still had a gram or so of my hexuronic acid. I gave it to him to test for vitaminic activity. I told him that I expected he would find it identical with vitamin C. I always had a strong hunch that this was so but never had tested it. I was not acquainted with animal tests in this field and the whole problem was, for me, too glamorous, and vitamins were, to my mind, theoretically uninteresting. ‘Vitamin’ means that one has to eat it. What one has to eat is the first concern of the chef, not the scientist. Anyway, Swirbely [sic] tested hexuronic acid. A full test took two months, but after one month the result was evident: hexuronic acid was Vitamin C.” (Jukes, T.; 1988: 1290)

Back in Pittsburgh, King and his colleagues were getting close to reaching a similar conclusion. Svirbely wrote to his former mentor in March 1932, telling him about the work they have done in Szeged. He also mentioned that he and Szent-Györgyi were submitting their findings in an article to Nature. (The Albert Szent-Györgyi Papers) (8) From this, it may seem that this prompted King to a hasty submission of what was still to him inconclusive results. There is evidence that this is not the case and the inference will be wrong. That the conclusions of King, based on work with lemon juice, was completed well before he received the letter from Svirbely. That he may have hastily submitted work for publication that was “sitting” with him after receiving word from Svirbely, is a matter that should have no bearing on the priority of the discovery. (Jukes, T.; 1988: 1292)

The following month, on 1 April 1932, Science published King’s paper where he announces that he discovered vitamin C and that it is identical to hexuronic acid. “King cited Szent-Györgyi’s earlier work on hexuronic acid where he gave Szent-Györgyi full credit for isolating it. (Jukes, T.; 1988: 1292)

He did however not credit him for vitamin C, despite the note he received from Svirbely, claiming this. As much as the appointment of Svirbely by Szent-Györgyi was a prudent decision, fully within his rights, so was it fully within King’s right not to mentioned the unpublished report on the findings of Szent-Györgyi of a link between vitamin C and hexuronic acid.

Glen King

C. Glen King. 1954.

The discovery by King was picked up quickly by the American press. (The Albert Szent-Györgyi Papers) This initial report “was followed by a more lengthy and descriptive report in the Journal of Biological Chemistry by Waugh and King in 1932.” (Halver J. E., and Scrimshaw, S.; 2006: 5, 6)

King remembers the sequence of events and the order of the communication from Svirbely as follows, “We then submitted our paper for the spring meeting of the American Society of Biological Chemists … and sent another manuscript to Science. A few weeks later in March, I received a letter from Dr. Svirbely (who had gone to Hungary to study with Szent-Györgyi the fall of 1931), in which he mentioned that they were just finishing their first assay in which animals grew satisfactorily and were protected from scurvy when given 1 mg/day of their crystalline ‘hexuronic acid’. They were sending a report of the assay to Nature.” (Jukes, T.; 1988: 1290, 1291)

The researchers in Szeged did not see things King’s way. In reality, King did receive the note from Svirbely before the publication in Science, (Jukes, T.; 1988: 1290, 1291) They were shocked by what they saw as an early announcement, prompted by the note. They felt that their findings had priority. “Astonished and dismayed, Szent-Györgyi and Svirbely sent off their own report to Nature, challenging King’s priority in the discovery” (The Albert Szent-Györgyi Papers)

Science did not record the date when thy received the submission from King. Today we only have the publication date. It is of course entirely possible that they received it well in advance before King received his note from Svirbely and the actual publication was delayed for an unknown reason. King may himself had reasons why he submitted it late. There are reports that he was in the process of checking certain facts and other work that was published that would have a bearing on his work if they were correct. (Jukes, T.; 1988: 1290, 1291)

The fact that the note and timing of the publications became such a controversy is understandable. Both worked hard over many years on identifying vitamin C and each felt that they had a claim to its first identification. They worked independently and, at the same time relied on each other’s work. In the case of Szent-Györgyi, through his identification of hexuronic acid and in King’s case, in the establishment of the techniques for analysis that was transferred by Svirbely. The consternation that followed in both camps after the publication of King’s work and when Szent-Györgyi was credited with the discovery and isolating vitamin C was to be expected. Such is life. It makes for, as Jukes puts it, one of the strangest accounts of the discovery of a vitamin.

Further work by Svirbely and Szent-Györgyi (1932) confirmed that Hexuronic Acid was vitamin C. (6) (Daniel E. P. and Munsell H. E; 1937: 5) “The fact that King had worked on the problem for over five years was well-known in the scientific community. Especially in the United States and he had “many supporters, who were ready to vilify Szent-Györgyi as a plagiarist.” However, Europeans and British scientists also knew about the work of Szent-Györgyi’s and his “long history with this anti-oxidant substance”. They accepted his claim of being the first to discover vitamin C. (The Albert Szent-Györgyi Papers)

Albert Szent-Gyorgyi and his laboratory staff at Szeged.jpg

Albert Szent-Gyorgyi and his laboratory staff at Szeged, Hungary

Its Structure

The emphasis now shifted to understand the structure of vitamin C. A tentative formula for vitamin C was suggested by Hirst et al (1932) and Herbert et al (1933). (7) (Daniel E. P. and Munsell H. E; 1937: 5) Even though Szent-Györgyi’s credit for the first identification of vitamin C was a bitter and lifelong disappointment to King, together with his research team, they published over 50 papers on ascorbic acid’s characteristics, deficiencies, and enzyme activities in various animal tissues between 1932-1942 (Halver J. E., and Scrimshaw, S.; 2006: 5, 6)

Haworth, a Birmingham (U.K.) chemist, received from Szent-Györgyi a sample of his “hexuronic acid, and in 1933, “in a series of impressive papers, the Birmingham chemist, using both degradative and synthetic procedures, described the structure of the molecule (Hughes 1983). The molecule was synthesized simultaneously, but independently, by T. Reichstein in Switzerland and by Haworth and his colleagues in Birmingham, both groups using essentially the same method.” (Hughes, R. E.; 2000)

The work of King and his research team came to fruition when Burns and King reported the synthesis of 1-C14-L-ascorbic acid in Science in 1950.” (Halver J. E., and Scrimshaw, S.; 2006: 5, 6) Over the years, the story of the analysis by Szent-Györgyi and Svirbely would become part of Chemical history’s folklore.

Important Lessons

The history of the discovery of ascorbate becomes an important introduction into our future consideration if its mechanism and functionality. It introduces us to biological combustion processes and ascorbate’s value as reducing agents.

It takes this vitamin out of the realm of academia and makes it “accessible” by giving it a human face in the persons of King and Szent-Györgyi. Szent-Györgyi tells a story involving his wife and supper that gave him the inspiration to examine paprika for a possible source of vitamin C.

In 1933, he was looking for additional, natural sources of ascorbic acid to use in further study. Orange and lemon juice have high levels of ascorbic acid, but they also contain sugars that complicated purification. “Szent-Györgyi solved the problem by making imaginative use of the local speciality, paprika.” (Schultz, J.; 2002)

“Szeged is the paprika capital of the world.” Szent-Györgyi accounts for how his wife prepared supper one night with fresh red paprika. He writes, “I did not feel like eating it so I thought of a way out. Suddenly it occurred to me that this is the one plant I had never tested. I took it to the laboratory … [and by] about midnight I knew that it was a treasure chest full of vitamin C.” (Schultz, J.; 2002)

Within weeks he was able to extract almost 1.4L of pure crystalline ascorbic acid from paprika, “enough to show — when fed to the vitamin C-deficient guinea pigs — that the acid was equivalent to vitamin C.” (Schultz, J.; 2002)

The story of the discovery of ascorbate is a human story. Rivalry, controversy, and disappointment but also of triumph, tenacity, discovery and the creative mind. To us in the meat curing industry, ascorbate would become the reducing agent of choice in our brine preparations and the story of its discovery, an example of a life of passion, excellence and another contribution by the favourite spice of Roy Oliver (the first production manager for Woodys Consumer Brands) – Paprika!

It is true, my son, that when I pick a piece of bacon up or cook it, that the names and places, the stories of the people who contributed to unlocking its secrets flash through my mind! It is like a flood of information that creates an avalanche in my brain! Your proximity to my quest makes you guys my most important collaborators in this grand quest and I celebrate you and your sister as we near the end of our quest. Besides you guys, there is Minette who is my greatest encouragement in this work.

Well, my son, there you have my Ascorbate-Letter.  The last chemical we look at is the alternative to ascorbate, Erythorbate!

Warm greetings from Cape Town!

Dad and Minette


Further Reading

Concerning the Discovery of Ascorbate


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Notes

(1) The Function of Ascorbate in Bacon Curing. There are at least four benefits in using ascorbate in meat curing.
a. Ascorbate or its isomer, erythorbate was originally used to speed up cured meat colour formation. (Pearson, A. M. and Tauber, F. W.; 1984: 53) It achieves this apparently by reducing the brown meat pigment, metmyoglobin to myoglobin with its purple-red colour. (Chichester, C. O.; 1984: 14)
b. “Ascorbate reacts chemically with nitrite to increase the yield of nitric oxide from nitrous acid. Nitric Oxide is responsible for meat curing.” (Pearson, A. M. and Tauber, F. W.; 1984: 53)
c. “Excess ascorbate acts as an antioxidant, thereby stabilising both colour and flavour. It prevents rancidity and the fading of sliced bacon when exposed to light. It achieves this through the prevention of heme-catalyzed lipid oxidation which results in both pigment degradation and rancidity. As long as excess ascorbate is present, the pigments are protected against breakdown. (Pearson, A. M. and Tauber, F. W.; 1984: 53)
d. Under certain conditions, ascorbate has been shown to reduce nitrosamine formation. (Pearson, A. M. and Tauber, F. W.; 1984: 53)

Only sodium ascorbate or sodium erythorbate (as opposed to ascorbic acid and erythrobic acid) are used in meat cures since ascorbic and erythorbic acid reacts with nitrite to form nitrous oxide. Nitrous Oxide is dangerous in confined spaces and its formation reduces the amount of nitrite available to participate in meat curing. (Pearson, A. M. and Tauber, F. W.; 1984: 53)

2. The Function of Nitrite and Nitric Oxide in Bacon Curing
Nitrite is the starting ingredient in meat curing. It undergoes several reactions in the meat, ending with the formation of Nitric Oxide. Nitric Oxide is the active ingredient that combines with meat pigments.

3. Articles I have written on the subject of nitrite in curing brines.

Formal Article’s:

Concerning the direct addition of nitrite to curing brine

Concerning Nitrate and Nitrite’s antimicrobial efficacy – chronology of scientific inquiry

Concerning Ladislav NACHMÜLLNER and the invention of the blend that became known as Prague Salt

 

4. Tillmans, J. and Hirsch, P. Über das Vitamin C. Biochem Ztschr 250: [312] – 320; Zilva, S. S. 1927. The Antiscorbutic Fraction of Lemon Juice. v. Biochem. Jour. 21: 689 – 697; 1928. Jour 22: 779 -785

5. Szent-Györgyi, A. 1928. Observations on the Function of Peroxidase Systems and the Chemistry of the Adrenal Cortex. Biochem. Jour. 22: 1387 – 1409. illus.

6. Svirbely, J. L. and Szent-Györgyi. 1932. The Chemical Nature of Vitamin C. Biochem. Jou. 26: 865 – 870.illus. and by the same authors, Hexuronic Acid and the Antiscorbutic Factor. Nature [London] 129: 576

7. Herbert, R. W., Hirst, E. L., Percival, E. G. V., Reynolds, R. J. W. and Smith, F. 1933. Constitution of Ascorbic Acid. Jour. Chem. Soc. [London] 1933 (pt. 2): 1270 – 1290. and Hirst, E. L. 1932. Hexuronic Acid as the Antiscorbutic Factor. Nature [London] 129: 576 577

8. King, C. G. and Waugh, W. A. 1932. The Chemical Nature of Vitamin C. Science (n.s.) 75: 357 – 358 and Waugh, W. A. and King, C. G. 1932. Isolation and identification of Vitamin C. Jour. Biol. Chem. 97: 325 – 331. illus. (Wikipedia. Beriberi)

9. The first person to postulate that certain foods contained “accessory factors” (in addition to in addition to proteins, carbohydrates, fats, and salt), necessary for human life was Sir Frederick Hopkins in 1898.

References

The Albert Szent-Gyorgyi Papers. Szeged, 1931-1947: Vitamin C, Muscles, and WWII. U.S. National Library of Medicine

Carpenter, J. K.. 1986. The History of Scurvy and Vitamin C. Cambridge University Press.

Chichester, C. O.. 1984. Advances in Food Research, Volume 29. Academic Press, Inc.

Daniel E. P. and Munsell H. E. 1937. Vitamin Content in Foods. United States Department of Agriculture.

Halver J. E., and Scrimshaw, S.. 2006. CHARLES GLEN KING 1896–1988. A Biographical Memoir. Biographical Memoirs, VOLUME 88. National Academy of Sciences.

Hughes, R. E.. 2000. Vitamin C. Cambridge World History of Food. 2000. Editor: Kenneth F Kiple & Kriemhild Conee Ornelas. Volume 1. Cambridge, UK: Cambridge University Press.

Jukes, T.. 1988. The Identification of Vitamin C, an Historical Summary. University of California, Berkeley, CA 94720, from American Institute of Nutrition. Received 29 lune 1988. /. ÑutÃ-.118: 1290-1293, 1988

McCollum, E. V., The newer knowledge of nutrition, New York, 2nd edition, 1922.

Pearson, A. M. and Tauber, F. W.. 1984. Processed Meats, second edition. AVI Publishing Company, Inc.

Pereira, C., Ferreira, N. R., Rocha, B. S., Barbosa, R. M., Laranjinha, J.. 2013. The redox interplay between nitrite and nitric oxide: From the gut to the brain. Redox Biol. 2013; 1(1): 276–284. Published online 2013 May 9. doi: 10.1016/j.redox.2013.04.004

Ridd, J. H.. 1998. Some Unconventional Pathways in Aromatic Nitration, Acta Chemica Scandinavica, 1998: 52: 11 – 22

Semba RD. 2012. The discovery of the vitamins. Int J Vitam Nutr Res. 2012 Oct;82(5):310-5. doi: 10.1024/0300-9831/a000124.

Schultz, J.. 2002. Albert Szent-Györgyi’s Discovery of Vitamin C, International Historic Chemical Landmark. On occasion where the American Chemical Society and the Hungarian Chemical Society designated Albert Szent-Györgyi’s work in biological combustion and the identifying of vitamin C as an International Historic Chemical Landmark with a ceremony at at the University of Szeged Albert Szent-Györgyi Medical Faculty in Szeged, Hungary.

Images

Picture 1: Casimir Funk. http://beforeitsnews.com/health/2014/08/synthetic-vitamins-are-toxic-2545050.html

Picture 2: Albert von Szent-Györgyi. http://www.chemistryexplained.com/St-Te/Szent-Gy-rgyi-Albert.html

Picture 3: C. Glen King. 1954. http://www.asbmb.org/uploadedfiles/aboutus/asbmb_history/past_presidents/1950s/1954King.html

Picture4: Albert Szent-Gyorgyi and his laboratory staff at Szeged, Hungary: https://profiles.nlm.nih.gov/ps/retrieve/Narrative/WG/p-nid/149/p-visuals/true