Tasty Mould: Quorn, Tempeh, and Huitlacoche

Many vegetarians probably have heard of these protein alternatives (Quorn and Tempeh) but I find it surprising how it is not actually common knowledge what sort of process has gone into the invention and production of these popular vegetarian protein foods. I am not a vegetarian, but I have been very interested in cultivating fungi and soy-product production methods. I think a useful starting point for my research would be to find out how these interesting vegetable proteins are made.


This is a piece of quorn from the dinner I had yesterday

In the 1960s it was believed that there would be a shortage of protein-based foods by the 1980s due to the growing world population. This did not happen. The saprophytic fungus (mould) known as Fusarium venenatum was discovered growing in Marlow, Buckinghamshire in 1967. Saprophytic means that it obtains food osmotically from dissolved or decaying organic material such as soil. For a decade it was originally misidentified as Fusarium graminearum (which alarmingly, is another mould which is considered a serious plant pathogen, producing mycotoxins in cereal crops). (Source) Through a joint venture between Rank Hovis McDougall and Imperial Chemical Industries, a particular strain of the fungi known as Fusarium venenatum, PTA-2684 was produced, after a ten year evaluation program to select and produce the best mycoprotein product for human consumption. Mycoprotein is the name of the product itself, derived from PTA-2684, in which the ribonucleic acid (RNA) content of the fungi has been reduced.

Oxygenated glucose syrup (the food-grade carbohydrate substrate) is poured into a fermentation vat and inoculated with a pure culture of F.venenatum spores (axenic fermentation). It is oxygenated so that the F.venenatum can respire, and excess CO2 is removed from the vat. Nitrogen is added in the form of ammonia to simulate the production of protein, and vitamins and minerals are added to improve the growth of the fungus. The temperature of the vat is kept at a constant to ensure the optimal growth of the fungus. It can grow very fast, doubling its mass every five hours. Finally it is treated with heat to remove excess levels of RNA as excessive DNA or RNA can result in uric acid (from the nucleic acids) being metabolised in the human body when the quorn is digested (which can eventually result in gout).

The hyphae (long, branching filamentous structure of the F.venenatum fungus) have a high length-diameter ratio and are morphologically similar to animal muscle cells, making it suitable as a muscle fiber replacer. Its nutrient profile is favourable and 100g of mycoprotein typically contains about 11.25g of protein, 6.258 of fiber, 3.258 of fat, 2.5g of carbohydrate, and 85kcal of energy.”

Food grade specifications of Mycoprotein (Source):

The two partners RHM and ICI invested on patents for growing and processing the fungus and other intellectual properties in the Quorn brand. The product was named after the village of Quorn in Leicester. Sainsburys agreed to stock the brand in 1985, which was its big break into the UK market – and later expansion into the Europe and North America market. All the Quorn in UK and Europe is produced in Marlow Foods’ factory in Stokesley.

In 2002 Marlow Foods was told by the British Advertising Standards Authority to delete the claim that it was a “mushroom protein” unless it “also gives equal prominence to either the ingredient’s fungal origin or explains its technical origin as a mycoprotein, found naturally in the soil but then put in a glucose medium and fermented.” (Source)

Searching on the internet yields images of advertising for Quorn back in the early 2000s with the description of Quorn as a “mushroom protein”. Perhaps it would be useful to try to discern the difference between Mushrooms and Fungi here. Mushrooms are the fruiting bodies of fungi, and only certain types of fungi produce mushrooms. Technically speaking if a mushroom is a banana then a fungi would be the banana tree, so if we call a mushroom a fungi that would be a bit like calling a banana a banana tree instead. A slightly confusing thing is that the word “Fungi” comes from the latin word “Fungus” which literally means mushroom. But when we say fungi today it should mean things like mould, yeast, mildew, mushroom. I haven’t put Lichen in the list because they are technically composite organisms consisting of a fungus and an algal species capable of photosynthesis growing together in a symbiotic relationship.


Tempeh [Image Source: Ivan Lian on Flickr]

Tempeh is usually made using the mould known as Rhizopus olligosporus. The Rhizopus genus fungi are very common and include the common mould you see on top of spoiled food (Rhizopus nigricans is the common bread mould). Rhizopus olligosporus is the main mould used because this mould has the “strongest protease and lipase activity which are ideal for breaking down the soybean’s abundant proteins and fats), combined with the weakest amylase activity, making it excellent for producing tempeh from cereal grains or grain-soy mixtures.

To produce Tempeh, whole soya beans are first soaked and dehulled because the soya hulls are fibrous and not digestible for R. olligosporus. After that the beans are cooked, and then inoculated with R. olligosporus. Eventually the incubated beans and R. olligosporus will turn into one whole cake with the white mycelium (the vegetative mass of hyphae produced by the fungus) binding all the beans together. It seems that tempeh could also be made on other starchy beans but the traditional bean used for Tempeh is soy bean.

I could not find how tempeh was originally made or how it was invented. No story about how a tea leaf fell from a tree into someone’s glass of hot water, just some rumors about indonesians leaving a bunch of cooked soybeans out until they got moldy (but tasty). There is a book written in 1985 titled “History of Tempeh and Tempeh Products (1815-2011)” by William Shurtleff and Akiko Aoyagi and this very comprehensive account of tempeh does not quite elucidate its very first origins, only the scientific attempts by western/japanese scientists to identify and define the mould that is used to create tempeh. Where did the the mould come from then? Where did the indonesians get the mould in the first place? Was it all a matter of trial and error, or of leaving their beans out and hoping the right mould would come along and infect their soybeans? Surely there was a slightly more organised history to this fermented bean product? The term itself “tempeh” originates from Central Java and is not derived from the Chinese which also have many soy foods which usually start with the prefix tau/tao.

What makes it harder to find out more about the traditional origins and methods of producing tempeh is that scientific research on methods of producing tempeh through the years – particularly that of the method by Martinelli and Hesseltine (1964) in which partially cooked, inoculated soybeans are incubated in a perforated plastic bag and frozen after incubation – is apparently responsible for influencing methods for producing tempeh commercially in Java as well as in smaller domestic quantities in homes today.


Corn Smut [Image source: International Maize and Wheat Improvement Center on Flickr]

I’m also morbidly fascinated by Corn Smut or Huitlacoche, a terrifying corn dish I once ate in Mexico. It was introduced to me as the “mexican truffles” at a posh hotel restaurant, and my friend Luis had waxed lyrical about the amazing taste of these “mexican truffles”, but I was still very shocked when I cut open my omelette and saw these unholy white-grey corn tumours slowly oozing out in a puddle of little black spores. They had a rather… um… “interesting” cheesy taste but their visual appearance, to the uninitiated, is admittedly hard to get over.

Corn smut is apparently one of the oldest plant diseases to be illustrated in drawings – first being figured in the Florentine Codex which was prepared soon after the Spanish conquest of Mexico in 1519 (cue an hour’s futile digression into looking up aztec codices…). The Aztecs also apparently consumed them and painted them in early murals.

[Image Source: Tania De la Paz on Flickr]

Ustilago maydis is a dimorphic fungus which grows in two ways: one as a single-celled haploid form on dead plants, and another as a parasitic, filamentous fungus which invades a living plant. It is a plant pathogen which affects seeds and flowers of cereals, wheat, corn, and grasses – and mainly corn, which is an important staple crop in Mexico. The Ustilago maydis relies on other plants like corn in order to complete its lifecycle.

When corn is infected, the normal kernels of corn on the cob are replaced by grossly inflated tumors which are the palpably swollen and enlarged cells of the infected corn plant, along with fungal threads and blue-blackish spores on the inside. Eventually the spores or teliospores burst out and fall off the corn, spreading in the wind. When it is being cultivated for human consumption, it is harvested before the teliospores burst out and becomes too mushy. Huitacoche has a short lifespan and has to be consumed within a short bracket of time. Although I am not sure if people eat it specifically for nutrition, when infected, the corn does have an increase in lysine which is an important amino acid for humans.

It is hard to decide whether the U.maydis is a detrimental or positive parasite for farmers. It can cause severe crop loss, yet in Mexico the swollen corn tumors are popular luxury foods. Farmers have been known to intentionally infect their crops with the fungus by scratching stalks of corns at their base with infected soil. It significantly increases the value of their corn when it is turned into corn smut, and it seems it is being researched as a solution for generating potential employment and income for farmers living in rural areas that already traditionally grow corn but are facing economic difficulties.

The etymology of huitlacoche is also particularly interesting. It comes from the Nahuatl word “cuitlacochin” which is thought to be from the Nahuatl words “cuitla” (excrement) and “cochtli” (sleeping). This is significant to the Nahuatl excrement does not only have the significance of waste but is often considered to be a distillation of food and wealth – for example, the Nahuatl word for “Gold” is teocuitlatl which is from “teotl” (god) and cuitla (excrement). I have always found this conjunction of waste/consumption and wealth/power to be of fascination to me.

Mould + Food = PROFIT???

The makers of Quorn seem keen to brand it as a mushroom-related product rather than as something that comes from what is basically mould from soil. Could it be because mushrooms are more palatable than mould? Most of my instinctual revulsion towards huitlacoche is that it looks like a mutated mouldy cob of corn – mainly the terrifying mouldy spores that burst out of the cells. Those who know my food idiosyncrasies will also know that I absolutely cannot consume blue cheeses or anything that is conspicuously mouldy, and am extremely cautious around fermented foods (especially dairy) that are meant to be intentionally sour (I am still very nervous about sour cream and vinegar). I see the presence of mould and a sour taste as possible indicators that a food has gone bad and should be disposed of. Logically, I can understand that they are not dangerous and perhaps even nutritious, but the fear of such foods (and of being sick because of consuming them) is a completely a physical reaction for me. I guess the idea of eating mould or a “waste” product, and even treating a “waste” product as a delicacy, is physically revolting/appalling even if I can identify it as being quite ideologically interesting.

In “The Accursed Share”, Bataille writes, “On the whole, a society always produces more than is necessary for its survival; it has a surplus at its disposal. It is precisely the use it makes of this surplus that determines it: The Surplus is the cause of the agitation, of the structural changes and of the entire history of society.” According to his theory of consumption, the accursed share is this excess portion of the economy that is destined to be spent in one of two ways: (1) to be spent as luxurious without gain (in the arts, in non-procreative sexuality, in lavish spectacles and monuments or (2) in outrageous and catastrophic outpourings (war, sacrifice, religion; a sacrifice so great that it even threatens the prevailing system).

Corn smut is a blight on corn and can lay waste to the entire crop if not controlled, so in effect it is a luxury in corn-centric Mexico where corn is the most important staple crop and is usually cherished and protected in most other circumstances. The corn plant is intentionally sacrificed through infection by the fungi, which kills the corn and makes it eventually no longer able to reproduce as corn. The infected corn cannot be used as staple crop; by being useless it is free, not subordinated to the normal demands of useful production; its price rises to that of a luxury good. Perhaps I am saying this only because its appearance makes me not exactly want to put it into my mouth – so I like to think that people came to love its taste because they associate it with luxury. Although I suppose in reality not everyone might be governed by such complex rules… what if for the most part people actually, really, really, just like the taste of it?

Bataille on the sacrifice: “The victim is surplus taken from the mass of useful wealth. And he can only be withdrawn from it in order to be consumed profitlessly, and therefore utterly destroyed. Once chosen, he is the accursed share, destined for violent consumption. But the curse tears him away from the order of things; it gives him a recognizable figure, which now radiates intimacy, anguish, the profundity of living beings.”

Some Burning Questions that may never be answered

Quorn: What were the circumstances under which they discovered the soil fungus that was to be used to make quorn? Were the researchers simply looking all around nearby natural environments close to their laboratory for stray cultures of mould? Where exactly did it come from, and where can i find this mould in nature today? Did they really study 3000+ fungi before selecting this particular fungus? Is there more of this fungi in the world today because it is being so intensively cultivated and examined in labs today?

Tempeh: How did the first tempeh get made? How were tempeh starter cultures consistently put together before western and japanese scientists started investigating it and meddling around with it? Was it really just some human leaving out some old beans and them getting infected with fungi and people discovering that mouldy soybean cake was tasty?

Huitlacoche: What was the motivation behind the first human who decided to eat huitlacoche? Why would anyone eat a horrific looking corn – driven to it by hunger or desperation or madness? Does the revolting appearance add to the frisson and people’s overall enjoyment of huitlacoche?

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