The 2019 sequel to my 2016 article in Brewery History 

Further evidence on the essence of gruit
Trough the ages people have wondered what wat the nature of gruit was. Many, often bizarre theories have formed and were also rejected. Most often gruit was interpreted as grain or malt, but people just couldn't figure out how.
Today gruit is often seen as a collection of herbs, and this hinders a true understanding of the matter. Sources simply continue to point to grain and malt. What about the herbs, one might ask. Well, they were certainly there in some places, but they were just herbs and were also called herbs. Below I will prove gruit was indeed a product made from grain.

A piece of bookkeeping about gruit in Cologne, 1391; 'Ausgaben eines halben Jahres zur Ausnutzung der von Hermann Goch gepachteten Gruth. In deim ersten maende gaf ich us in urber der grous van 23 malder maltz zo tolle 8 mark. Item van demselven maltze zo malen 21/2 mark'.
Hermann Goch bought malt for making gruit is what he wrote himself literally.
What did Hermann Goch and many others do to make their malt into gruit? Well, there is an overwhelming and still growing evidence that gruit was basically concentrated wort, also in places with big collections of herbs. Things could be added to this concentrate and there are instances of boiling yeast along with wort thus possibly adding nutrition for yeast growth. Some specific herbs could perhaps have been added to the concentrate, but many types of herbs are simply unsuited for doing so. We do not argue there were no herbs added to beer, that was certainly the case in Cologne and various other places. But herbs present in a gruithuis do not automatically make them into gruit.
It is impossible to describe all practices and methods of brewing over the many centuries of brewing with gruit, but there is, as mentioned above, much evidence about boiling down wort, evaporating water, concentrating the maltose sugars, thus making a durable product for later use, for trade, for facilitating smaller scale brewers to make a more robust beer. This was done in many places in a wide area, including Danmark, Britain, Northern France, Belgium, the Netherlands and parts of Germany on the border region of the Netherlands.
There are many misconceptions surrounding the history of beer, and a related one is the idea gruit was used before brewing with hops. There is rather solid evidence about brewing with hops well before and around the year 1000. With the growing population in the high middle ages hops must have become scarse in certain places, thus causing a search for alternative methods of brewing. Export trade of durable hopped beer from Hanseatic seaports like Bremen and Hamburg started in the 13th century while at the same time brewers made gruitbeer in places like Cologne. Below I will present some of the evidence on the nature of the substance called gruit.

Gruit (Latin: grutum, grute) had multiple identities: from an old tax law called 'gruytrecht' (Latin: ius grute); the beer made with gruit; the process of making gruit (the verb “gruyting”) to the actual substance, which was also indicated with gruit. The focus of this text is only about identifying the nature of gruit.

Latin
Below some of the present evidence on the nature of gruit, with a special focus on well known early Latin sources and terms:
Fermentum (or fermentatae (3)): added concentrated wort will result in an extra or elongated fermentation and a thicker, stronger, more durable beer and could have been used at almost any stage of brewing.
Concentrated wort explains the Latin 'soppa fermenti' (4), and the vulgar 'gruetsoppe' (5).
Polenta (6) was translated by de Lobel (Latin: Lobelius) as Naerbeer or Graut, being concentrated wort.
Levarentur (7) speaks of levitation or the rising of beer during fermentation.
One of the clearest early (1074) indications about the nature of gruit is this one: frumentum vulgariter dicitur Gruyt. Translated the grain ordinarily called gruit (8).
Conservabimus (9) is probably about conservation.
Latin pigmentum (10) could be caramelization or a similar reaction when making concentrated wort. When boiling down wort the liquid will become ever darker and will eventually be a very dark brown sticky and durable substance.
In Latin sources there is no mention of herbs in connection with gruit.

Coroners
Two British sources (11-12) from the 13th century in Latin show us what was involved in making gruit. In both instances there was a fatal accident recorded by a coroner; people fell into a large vat of boiling gruit (Latin: grutum bulliente). These two sources are consistent with several others: for instance the gruit kettle that was also present in gruithouses on the continent. Boiling gruit in a large kettle is the strongest possible evidence for our theory on the essence of gruit. The contents of the kettle could only have been boiling wort, for boiling the various herbs that were present in continental gruithouses makes no sense at all. The kettle being large was for added efficiency, the durable gruit made in the kettle could be distributed to a number of brewers with much smaller kettles. They could have made a stronger and better beer for their clientele in such a way.

Recipes
The connection between 'grutum', 'polenta', 'gruit' and 'grout' is made by many. Contemporary researchers sometimes focus on regional differences, but a broader view, however, will reveal that gruit was essentially the same everywhere. It was indispensable to make good beer in the absence of hops. This was also the reason why in some places a legal system (Latin: ius grute) could develop around it.
Lobelius (13) was a scientist and intellectual with such a broader view and mentions his ancient greek colleague Dioscorides as an early source of Polenta being a porridge made of concentrated wort. He uses it to make beer (Enghelsch bier Ael geheete, translated: English beer called Ale) and to make various medicines. He further indicates it was eaten with bread in Delft (Holland).
Historie of the World, one of the largest single works to have survived from the Roman Empire was translated into English by Philemon Holland (14) and describes the making of 'The ordinarie drie grout or meale also Polenta' in detail.
Charles du Fresne (15) describes grutum as a 'boullie qui se saifoit avec de l’eau & toute sorte de farine', translated: porridge made with water and all kinds of flour. Various editions of his 'Glossarium' (16) make the connection between grutum and Granamelum, Anglis Grout, à Saxonico Grut, Far, condimentum cerevisiae.
There are more recipes for making grout (17) 'To make grout' and many later British sources and recipes that indicate grout is essentially concentrated wort. One of them is of particular interest and describes 'The method of brewing beer, before the use of hops' and 'It was neccessary first of all to make the grout' (18).
The dictionary Anglo-Latinus by the Camden Society (19) features a story on 'Growte for ale' and links it to medieval Latin grutum or grudum, old French gru or grust and Anglo-Saxon grut.
Van de Kieft (20) mentioned one of the oldest sources of gruit, the 11th century 'polenta cervisie que vulgo maire' and explained it as 'une sorte de bouillie', translated: a kind of porridge.

Malt
Gruit is connected to malt in Dordrecht, Arnhem, Deventer, Zutphen, Cologne and Dortmund.
Dordrecht (21): 'van elken hoede mouts hoir gheld also groet, als syt gheven souden van anderen biere, dat si met grute gruten souden'. Dordrecht (22): 'zijn mout dat dair toe behoirt ende dair binnen zal him die gruter zine grute gheven'. In both instances the amount of gruit is tied to the corresponding amount of malt used for the beer.
Arnhem (23): 'elke mauder mouts gruten sal'. This also ties the amount of malt to gruit, but could also be interpreted as simply a tax related to the amount of malt.
Dordrecht (24): 'Item so wat brouwer, die zijn ghelt ende mout int gruuthuus niet en brocht, als zede en ghewoente is'. Here brewers bringing their malt into the gruithouse is presented as an old custom. In Dordmund we find a regulation about whether or not to bring malt into the gruithuis under various conditions; 'wie gerstenbeer vele wolde brouwen, solde dar nichts dem Gruethues van dem malder malts geven' (25).

Gruit is distinguished from herbs in both Arnhem and Cologne; Arnhem (26): 'verboden gruit ofte cruyt elders te halen'. Cologne (27): 'einig grudt noch kraudt im bier zu thun'.

Various workflows
Boiling gruit makes a firm connection between the Latin and various 'vulgar' variants of the name, both on the continent as well as in Britain. Although tax laws in various places might have been different, the basic nature of gruit as concentrated wort remains the same. Wort was concentrated and could be mixed in all kinds of workflows and with all kinds of substances, like wort, herbs and yeast. Its compact, durable and sticky nature must have made it easy and logical to do so.
Concentrated wort is durable and fits a society that doesn't waste any food and is very usefull for a brewer. It can be employed in many stages of brewing, it is consistent and logical; it was basically the same substance everywhere. There is a plain recipe by Lobelius (28): Graut wordt aldus ghemaekt, translated: 'Graut is made like this', and there is more to follow (29-30).
Many Latin dictionaries make the connection between the Latin Grutum and British (Anglis) Grout, German Grut and other variants. Concentrated wort is consistent with: 'a porridge called graut, -a favorite dish of the Northmen-, for the cooking of which an unusually large kettle was provided'(31).

Yeast
Although descriptions of a practical workflow of making gruit are scarce, there is a few in which it is combined with fermentation or adding yeast (32, 33). Boiling yeast could result in added yeast nutrients in gruit. Gruit made in this way places the Latin term 'fermentum' in a broader perspective.

Herbs
Much of the above evidence rules out gruit as simply a mixture of herbs, but some knowledge of the brewing process could also be helpful to understand why herbs were not what was 'made' while manufacturing gruit. Hops have to be boiled for some time to be able to preserve beer, add their bitterness and balance the original sweetness. Most other herbs however will lead to a very bad tasting beer when presented to a brewer boiled for a fair amount of time. This could be compared to making tea by boiling the tealeaves. There are various methods to impart delicate herb flavors to beer, but that is outside the scope of this article. It is important to understand that herbs were not likely to have been what was boiling in the kettle mentioned earlier.

Confusion
Confusing herbs with gruit is understandable because in various cases herbs were a important part of what went on in a gruithuis. Hermann Goch (1391) leased the gruit in Cologne and bought a lot of malt; 'gaf ich us in urber der grous van 23 malder maltz'. This could be translated as: 'I bought 23 units of malt for making gruit'. Still, in de detailed account of his business we can see he spent most of his money on 'kroutz' or herbs (34). Indeed various kinds of herbs were part of the business going on in the gruithuis. They could perhaps have been mixed with gruit and were likely to have been important to balance the sweetness of (unhopped) beer.
Aloys Schulte (1908) wrote a valuable essay on gruit and herbs, but in the end he returned to the 'grossen Kessel (caldarium)'; the big gruit kettle. 'Jedenfalls war die Bereitung der Grut an eine grössere Anlage gebunden', translated: 'anyway the preparation of gruit was tied to larger equipment' (35).
Finally there are some instances in with both are mentioned together; 'grudt noch kraudt', also in Cologne, but much later in 1593 (36). There was also hops in gruit; 'hoppe ind gruiss' (37) and hops mentioned in Deventer; 'humuli ad domus fermenti' (38). In Arnhem we find 'Die Gruyt of Cruyt anderswaer haelde of dede haelen dan in der Stat Gruythuys' (39), translated: 'Those who get or have somebody to get their gruit or herbs from elsewhere instead of the muncipal gruithuis', (will be fined a certain amount).
In all these cases one could argue herbs (and even hops) were part of gruit, but it remains clear they were not the same and certainly not the essence of gruit.

Conclusion
Although Gruit (Latin: grutum, grute) had many identities, I hope to have made it clear gruit was essentially wort that was boiled down, concentrated in this way to make it more durable and useful.

My online collection of sources on gruit has been ever expanding and contains many new items and recipes of gruit. I want to thank Hans Ebbing, Frank Boekhorst, Leen Alberts, Susan Verberg, and many others for helping me expand the collection. I do not want to disturb the compact nature of this article with the many new entries that are presented online. It is possible to go on unlimited about all kinds of aspects and variants about gruit in various times and places, but I hope for now to have shed some meaningful light on the subject.

Frederik Ruis

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1. Brewery History (2016) 166, p.50-53
2. Ebbing, H. (1994) Gruytgeld ende hoppenbier: Een onderzoek naar de samenstelling van de gruit.
3. Oorkondenboek van Holland en Zeeland (1866). p.45 negotium generale fermentatae Cervisiae
4. Cameraars-rekening, Deventer (1347) p. 274-280 de soppa fermenti II marcas VI solidi
5. Cameraars-rekening, Deventer (1345) p. 218 de fecibus fermenti dictis gruetsoppe
6. Elenchus Fontium Historae Urbanawe, van de Kieft (1967) p.296 Polenta cervisie
7. Miraeus Opera Diplom. Tom. I(1064) p.63 materiam faceret unde levarentur cerevisiae
8. Akademische Beiträge zur Gülch- und Bergischen Geschichte, Zweiter Band, Christoph Jakob Kremer (1776) p.205 fermento cervisie, quod frumentum vulgariter dicitur Gruyt
9. Archieven der Ridderlijke Duitsche Orde, Balie van Utrecht Volume 2 (1871) p.792 grutam et ius fermentandi per eadem tempora in jure suo conservabimus
10. Liste chronologique des édits et ordonnances de la principauté de Liège, Goddaerts (1873) p.5 pigmentum propre à faire de la cervoise
11. The Early records of medieval Coventry, Peter R. Coss, ‎British Academy (1986) p.50 in quodam plumbo pleno grut’bullientis
12. The Publications of the Selden Society (1896) p.15 grutum in quodam plumbo bulliente
13. Kruydtboeck, De L'Obel (1581) p.35 p.285
14. The Historie of the World, Philemon Holland (1601) p.561 ordinarie drie grout or meale also Polenta
15. Dictionnaire universel (1690) p.211
16. GLOSSARIUM, Auctore Corolo du Fresne, Domino Du Cange (1688) p.267 - 268 Grutum
17. A true gentlewomans delight (1653) p.36 To make grout.
18. Horda Angel-cynnan, Volume 3. p.72-73
19. Promptorium Parvulorum by Camden Society (1843) p.217 In medieval Latin it was called grutum
20. Acta Historiae Neerlandicae I, Van de Kieft (1966) p.68 une sorte de bouillie, entrant dans la fabrication de la bière
21. Groot Charterboek der Graaven van Holland, Tweede deel (1754) p.256
22. Handvesten, privilegien, vrijheden, voorregten, octrooijen en costumen, Dordrecht, 1770 p.150
23. Tijdschrift voor Geschiedenis 64e jaargang, Alberts (1951) p.334
24. De oudste rechten der stad Dordrecht, Fruin (1882) p.117
25. Die Chroniken der deutschen Städte, Erster Band: Dortmund, Neuss, (1887) p.330
26. G. van Hasselt's Arnhemsche oudheden Vol. 4 (1804) p.24-25
27. Ausführliche Darstellung der gerechten Ansprüche des Grafen zu Bentheim-Tecklenburg
auf die Herrschaft Bedbur (1788) p.70-71
28. Kruydtboeck, De L'Obel (1581) p.35
29. A choice manual of rare and select secrets in physick and chyrurgery (1653) p.34
30. The operative chemist, Gray (1828) p.866
31. Social Scandinavia in the Viking Age (1920) p.158
32. Horda Angel-cynnan Vol. III , Joseph Strutt (1776) p.72
33. The operative chemist, Samuel Frederick Gray (1828) p.866
34. Quellen zur Geschichte der Stadt Köln. Sechster band. (1879) p.55-57
35. Vom Grutbiere, Aloys Schulte (1908) p.131
36. Ausführliche Darstellung der gerechten Ansprüche des Grafen zu Bentheim-Tecklenburg
auf die Herrschaft Bedbur (1788) p.70 - 71
37. Die Kölner Zunfturkunden bis zum Jahre 1500, 2e band spezieler teil. Heinrich von Lowsch (1907) p.59
38. Cameraars-rekeningen Deventer (1344) p.158
39. G. van Hasselt's Arnhemsche oudheden Vol. 4 Moeleman Jr. (1804) p.25

All sources backing this article can be found in chronological order: History - Sources about beer - Gruit - Grutt - Gruijt - Grout - Graut

graut wordt aldus ghemaeckt

Graut is made like this.
One takes 6 or 8 pounds of crushed malt, boiling hot water 12 or 15 pounds, which mixed together and well stirred 6 times in a day, and with blanckets and straw very well covered soo long together in a clean barrel shall soak that it becomes thick as syrup. After that it shall be fired and boiled, and stirred very well to keep it from burning, till it is thick as porridge.

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