Mt guess that it was double decocted turned out to wrong. In reality, a triple decoction was performed. As the sole purpose of this experiment was connected with the brewing water used, I think we can be pretty sure that the mashing scheme was the same as in the full-size brew house.
The whole mash gets two rests, one at 55º C and another at 67º C. Which equate to a protein rest and saccharification rest, which I guess what you would expect. It looks like a fairly classic triple decoction mash.
Heineken seem to have been trying quite hard to replicate a beer in the Bavarian style.This is exactly the type of complicated mashing scheme employed by Munich brewers. However, this isn't how they brewed their Pils, which went for a simpler double decoction.
I can't imagine Heineken mash in anything like such a complicated manner today. I wonder how long they stuck with decocting?
|Beiersch 2nd Jul 1935|
|Mash in at 37º C (99º F)||20|
|Raise whole mash to 50º C (122º F)||5|
|Draw off first decoction and raise to 70º C (158º F)||30|
|Boil first decoction||30|
|Rest whole mash at 55º C (131º F)||15|
|Draw off second decoction and raise to 70º C (158º F)||20|
|Boil second decoction||20|
|Rest whole mash at 67º C (153º F)||10|
|Draw off third decoction and raise to 100º C (212º F)||5|
|Boil third decoction||20|
|Mash at 74.5º C and mash out (166º F)||5|
|Sparge at 75º C (167º F) and rest||60|
|Draw off main wort||65|
|Draw off srcond wort||115|
|Heineken Brouwjournalen van de proefziederij, 1935 - 1957 held at the Amsterdamse Stadtsarchief, document number 1785-1792, page 10.|