Oats, oat-malt and rolled oats in beer

Medieval and renaissance beers were characterized by the use of large amounts of oats. From the famous Domesday Survey of 1086 (1) we see ‘ale’ was made with oats as the main ingredient. The later Bremen export ‘rotbier’ (a hopped beer) was also made with around 80% oats and the Dutch ‘hoppenbier’ was based upon this. The relatively modern Koyt beer was still made with approximately 50% oats. There is a lot of confusion about this important part of the beer.

Rolled oats
The brewing of beer with oats was (in the past decades) ill-famed for its technical problems. To prevent a clogged and glutinous mass, rice hulls were added, lots of rice hulls. We can be pretty sure brewing with rolled oats or rice-hulls did not occur in the past. Our own testing with malting and brewing over the period 2012 to 2014 showed brewing with malted oats has no problems, provided that the smaller sized oat is taken into account when grinding (2). Everything needed to make a good beer can be present in malted oats including the necessary enzymes.

Brewing oats
To make good quality beer we need good malt, this used to be so obvious that in lots of instances it was not mentioned. Often it was mentioned though, and below I will provide some very clear historic examples (3). Over the course of centuries a special good quality brewing oat must have evolved. We see market prices of brewing oats appear in the 18th century and Lacambre mentioned them in his later mid-19th century writings (4). At last, for those who perhaps do not care about what brewers did in the past, we added a scientific study (2011) about the brewing with oats (5).

Frederik Ruis


Exploring the St. Paul’s Domesday Ale Recipe:
Medieval brewing praxis and modern recreation
Henry Davis And Steven A. Walton
Avista Forum Journal
p.18 - 31

domesday ale 1086



Brewing with 50% malted oats



Oorkondenboek van Utrecht
Oorkondenboek van het Sticht Utrecht tot 1301
Deel IV
Eerste stuk
1267 - 1283
Uitegeven door Dr. F. Ketner
’s Gravenhage


’tseventigh mudden melten van haver

[seventy parts oat malt
f ]

Oorkondenboek van Utrecht osu4 392


Rechtsbronnen van Utrecht


p. 366
CCLXV. Ordinancie vander brouwerye vanden dickenbyer.
Anno XIIIIcXLVII des Dinxdages na Margarete byden raide out ende nye.
Om die guede ghemeente onser stadt in neringe te brengen buten scade derzelver stadt, aen arbeyde, koern, torve, zolrehuere ende andere comanscap, die daer onder ghelegen is, ende nu kenlic is tot anderen steden zij die groit ghewyn ende ghenot daervan hebben, soe is gheordiniert eyne brouwerye te wezen binnen onser stadt ende stat vryheyt van dubbelden koyte in manieren hijr naebescreven:
1. Inden yersten zoe zelmen dit bier brouwen van zoevoell koerns als hijr nae volcht.
2. Item daer zellen in wezen X mudde haveren, VI mudde ghersten ende IIII mudde weyts aen moute, maect te samen XX mudde koerns; ende daer off zelmen brouwen XX volle grove vate biers, te weten elck vatt van X emmeren.
3. Item zoe wie dit dubbelde byer brout, die en zell anders gheen bier brouwen derwijlen hijt brout; mer als hij eenwisselt bier brouwen will, zoe zell hijt den sysmeysteren, beyde vanden hoppensys ende vanden inbrouwensys, een half jaer te voeren zecgen ende hem dat int laetste zysoen, eer hijt eenwisselde byer te brouwen aennemen zell, weder vernyen ende niet aennemen dan int beghinsell vanden zysoen, bij eynre penen van C lb. ende ewelic die neringe zoe dicke alst ymant dede.

[dickenbyer = dubbelden koyte
alle koerns, haveren, ghersten, weyts = moute (all grains were malted in double koyt)
f ]


Brouwerskeur Haarlem

Gemeentearchief Haarlem, Inv.I no.454, katern papier van 6 fol.
hoppen biers storten thien achtendeelen tarwe mouts ende zesendertich achtendeele haveren mouts

[ ten parts wheat malt and thirtysix parts oat malt
f ]



Neuw vollkommentlich Kreuterbuch
Jacobus Theodorus, Caspar Bauhin

Das Bier so aus Gersten und Havermalz gemacht oder gebrauen

havermalz 1613


Twee Sententien wt den name ende van wegen den hoogh-Moogenden
ende Edelen Heeren Staten Generael van de Vereenighde Nederlanden gepronuncieert in 's Graven-Hage
d'eene op den 4 Dec. anno 1610,
ende d'andere den 3 Julij 1615,
(Google eBoek)
na de copye, gedruckt by Hillebrant Jacobsz,


[Oat-malt from eight and a half to eleven dimes
f ]



Placcaet Resolutie, Generale Ordonnantie,
Mitsgaders Ordre van Verpachtinge ende Procederen
van Stadt Groningen ende Ommelanden
(Google eBoek)

wat aengelanght de Greynen ende Molt dat om te verbrouwen gemaelen sal worden
Ende van 't Haver-Molt elf stuyver

[And of the Oat-Malt eleven dimes
f ]



Placcaet. Resolutie.
Generale ordonnantie.
Mitsgaders ordre van verpachtinge ende procederen. Item particuliere ordonnantien ende instructien. Op 't collecteren. En innen. Vande generale middelen. Van stadt. Groningen ende Ommelanden
gedruckt by Arendina Sygers,

Om te Verbrouwen.
Garsten Moldt
Haveren Molt
Tarwen Moldt

molt 1707


Taalryk register der plaat- ofte figuurbeschryvingen der bloemdragende gewassen
Volume 1 (Google eBoek)
Johann Wilhelm Weinmann, Johannes Burmannus
Zach. Romberg,


De mouting daar van word omtrent gedaan als die van het Lucht-mout

Wat het brouwen betreft, dat geschied wederom byna gelyk als het ander bier, behalven dat dit veel langer en sterker koken moet, om de Haver zyne raauwheid te benemen.

Men nam in den beginne 30.scheepels van de beste Haver, en gemout zynde

[Malting was done in the same way as with Air-malt
f ]



Traité de la Fabrication des Bières et de la Distillation des Grains
Volume 1 (Google eBoek)
G. Lacambre

mais les avoines de bonne qualité dites Avoines de brasseur

(maar de goede kwaliteit haver die Brouwhaver wordt genoemd)



Brewing with 100% Oat Malt
Journal of the Institute of Brewing, July 2011

'The four final oat malts were then analysed separately using European Brewery Convention (EBC) methods.'

'The different malts were milled with a two-roller mill (0.7 mm distance between rollers) and 9 kg of grist was mashed into 32 L of water at 45°C according to the optimal mashing regime'

'It could also be used as lautering aid due to its high husk content'

'The fermentation of both the oat and barley wort followed the same trend, the only major difference was seen in the higher pH and lower alcohol content of the oat beer.'

'The flavour analysis of oat beer revealed some special characteristics such as a strong berry flavour and a better reaction towards staling, probably due to the presence of more antioxidants.'

'In addition, a beer of a different character is likely to be brewed from oat malt and might in time appeal to new consumers.'

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