Myth: 'Gruyt and Koyt are the same kinds of beer'

For decades there was a persistent misunderstanding about Gruyt and Koyt beer in the Netherlands. Perhaps because the names are phonetically similar people thought they were the same kinds of beer. Gruyt beer is the old beer without hops were durability was enhanced a bit through more alcohol due to a special brewing technique. Hopped beer could be lighter as well as more durable. Koyt beer is an innovative and relatively new beerstyle with hops that arose after 'Hoppenbier'.

Misinterpretation
Possibly by mistaking old regulations for a 'recipe' the confusion lasted until only recently. A document from Harlem dating back to 1501 mentions Koyt beer without the use of hops, further in the same document the old Hoppenbier is mentioned, also without the use of hops. The document dealt with the kinds and proportions of malt and the number of barrels one could fill (the strength of the beer) with one brew. The use of hops was simply outside the realm of this regulation.

What possibly added to the confusion is the fact that the amounts of hops can hardly be prescribed and hops were subject to taxation, which might have formed another reason for some confidentiality. This tax was called 'gruitgeld' and the name stuck while it became a taxation of hops.

New insight
The new insight has inspired Dutch brewers recently (2013) to try to make a true Koyt beer. Koyt beer had been around for about four centuries; it might have been any good after all. If they succeed they will be the only Dutch brewers to make a true Dutch style of beer.

Frederik Ruis

Beer in the Middle Ages and the Renaissance
Richard W. Unger
University of Pennsylvania Press,
2007

p.52
The industry changed dramatically in the closing years of the thirteenth and in the course of the fourteenth century with the introduction of a new kind of drink, a beer made not with gruit but with hops. The use of hops would start the second phase in the long-term development of northern European brewing, marking the transition from the period of preparation to that of product innovation.
p.64
Hopped Beer, Hanse Towns
the tax was called gruitgeld but their beer had hops and not gruit.
Ale made with gruit was a drink for the poor and the sick.

Duizend jaar Gouda: een stadsgeschiedenis
P. H. A. M. Abels
Uitgeverij Verloren
2002

p.95
Het zogenaamde kuitbier dat begin vijftiende eeuw in Holland opkwam, werd met hop gebrouwen...

'The so-called Kuit-beer that arose in 15th century Holland, was made with hops...'

Groot algemeen historisch, geographisch, genealogisch, en oordeelkundig woordenboek, behelzende zo het voornaamste, dat vervat is in de woorden-boeken van Morery, Bayle, Buddeus, enz...
(Google eBoek)
Brunel,
1729

p.169
1455 Goudsche Kuyt

Hertog Philips van Burgundië vergunde in 't jaar 1455 ten voordele der Goudsche brouwers, dat de hop-accyns op een broudsel...

'Duke Philip of Burgundy licensed, in the year 1455, in favor of Goudsche brewers, the hop-accyns on one brew ...'

Korte chronycke van vele gedenckweerdige geschiedenissen:
soo in de principaele steden van het hertoghdom van Brabant als in de stadt en provincie van Mechelen
Volume 1 (Google eBoek)
no pagenumbers
brewers regulation 1460
J. Jacobs
1747

de Hop Accysen...van der Coyten

'Hop tax..on Coyten'

Geschiedenis der heeren en Beschrijving der stad van der Goude.
Meest uit oorspronkelijke stukken bij een verzameld door
Cornelis J. de Lange van Wijngaerden
Tweede deel (Google eBoek)
Van Cleef,
1817

p.377
en geen ander kruid als hop

'and no herb except hops'