Heineken grists in 1939

Heineken had two basic types of grist: one for the pale beers and another for the dark ones. 

The pale grist was 80% pilsner malt and 20% rice. I’m not sure the exact form the rice took. It could have been flaked, simply ground into flour, or it could have even been in the form of syrup. The brewing record isn’t very specific. I’m guessing that its purpose was twofold, to lighten the body and colour and to save money. The slightly darker Export Pils also contained a very small amount of “kleurmout” (“colour malt”).

The short-lived Meibier was unusual in having a grist of 100% pilsner malt.

The grists for the darker beers were much more complex and, with the exception of Donker Lagerbier, adjunct-free. Three types of coloured malt were used: kleurmout, broeimout and caramelmout.

Kleurmout was a type of dark roasted malt similar to black malt. Caramelmout was a type of crystal malt. Nothing too complicated there. Broeimout is a different matter. Literally “heating malt”, it had a specific method of production.

“In the case of broeimout, there is no cooling during the germination process, so that the temperature rises quite high and the flour body dissolves a great deal. Due to the higher germination temperature, it is not necessary to kiln at a high temperature. The colour of the malt darkens due to the germination heat alone to about 30 - 40 EBC. However, broeimout cannot be 100% of the grist, as many enzymes have been destroyed by the higher temperatures. Amber malt is sometimes also called broeimout, but this does not always necessarily the case.” 

In addition, a small amount of “kleur”, a type of caramel, for extra colour.

Heineken grists in 1939
Date	Beer	Style	pilsner malt	kleur mout	broei-mout	caramel mout	rice	litres kleur
26th Dec	Do	Donker Lagerbier	69.70%	0.90%	6.00%	3.40%	20.00%	20
11th Dec	Li	Licht Lagerbier	80.39%				19.61%
12th Dec	Exp	Pils	79.83%	0.17%			20.00%
6th Dec	P	Pils	80.00%				20.00%
7th Dec	Bei	Münchener	89.22%	0.98%	5.88%	3.92%		28
18th Jan	Mei	Meibier	100.00%
7th Aug	Bok	Bok	94.00%	1.00%	3.00%	2.00%		15
Sources:
Heineken brewing records held at the Amsterdamse Stadsarchief, document numbers 834 - 1758 and 834 - 1759.