What could be a more obvious place to look than "Onderzoeking over het Gistgeslacht Brettanomyces"? (Investigation into the yeast type Brettanomyces') The Dutch author, knowing Brettanomyces played a role in Lambic brewing, clearly made a little trip down to Brussels to find out more. He picked a brewery you may have heard of.
"Thanks to the kind cooperation of Mr. A. Vossen, Director of Brasserie "Mort subite" in Brussels, I have been able to acquaint myself with the method of preparing "lambic". Essentially this is done as follows.
The grist for "Gueuze-Lambic" is a mixture of barley malt and unmalted wheat, in which the quantity of the latter raw material makes up 40 to 50% of the total deposit. After this mash has passed the usual temperatures for the protein degradation and saccharification, it is filtered, hops are added and the hopped wort boiled for about 5 hours. The amount of added hop is 800-900 grams per hl of wort.
To demonstrate better the significance of this number, it is important to note that for beer brewed in this country and also for the normal types of beer brewed in Germany, up to 250 grams of hops is added per hl of wort."
"Onderzoeking over het Gistgeslacht Brettanomyces" by Mathieu Theodoor Jozef Custers, 1940, page 24.
You can see that a large amount of hops is confirmed. Though this is much less - 2.8 to 3.2 lbs per barrel - than the 8 to 12 lbs specified in the 1932 Brewers' Journal article. Which source to trust? Not sure. It could just be different hopping rates at different breweries.
"The product thus obtained, after filtration, is put into flat coolers where it remains ± 24 hours; there is no artificial cooling.
During cooling, the wort takes numerous organisms from the air. After cooling the wort is put into wooden barrels of about 2 hl size and these vessels in a room with a temperature of 15 ° - 18 ° C.. Yeast is not added; A slow fermentation occurs spontaneously. A closing piece is placed on the barrels, in which a small opening is located; this opening closes iself automatically with exudates, which will float up through the action of the fermentation.
The beer remains 2 to 3 years in the casks and then after clearing it is filled into bottles where the fermentation and lagering continue at the same temperature for about 2 years. The product thus obtained is the so-called "Gueuze-lambic "; it has an original gravity of 13-14° Balling.
The resulting product of two to three years fermentation and lagering in the casks is already suitable for consumption itself. It is also sold on draught under the name of "gueuze".
"krieken-lambic" is "lambic", where an appropriate amount of cherries is added in the barrels.
In passing it should be mentioned here that "faro" and "mars" which are also Brussels special beers are prepared in a similar way to "lambic ", but these beers have a lower original gravity than "lambic "."
"Onderzoeking over het Gistgeslacht Brettanomyces" by Mathieu Theodoor Jozef Custers, 1940, pages 24 - 25.
I'll admit to not quite understanding the bit about the closing. Oh, the original book is in Dutch, by the way. It's my translation here. Exudates is what Google translate comes up with for the Dutch word "afscheidingsstoffen". If anyone has a better translation, let me know.
A gravity of 13-14° Balling, with the 90% attenuation you would expect from Lambic, leaves a beer of 6 to 6.5% ABV. Which is a bit higher than today. Two or three years in cask on the other hand is much like today. Though it confuses me that Gueuze-lambic is used for the version refermented in bottles and just Gueuze for the younger draught stuff. That's definitely different from current practice, where the names would be Gueuze and Lambic respectively.
Faro and Mars are once again said to be lower-gravity versions. No mention of sweetening, which I though was an essential feature of Faro.
""Lambic" is only be brewed in the cold seasons, viz. from October to April. In the last twenty years it has been attempted, through the use of pure cultures of the yeast and bacteria species generally found in "lambic", to shorten fermentation and lagering to 5 to 6 months and also to brew in the summer. However, this process has not made much progress.
For the fermentation of lambic Brettanomyces yeast is now considered essential; these probably also tend to get into the wort during cooling. This is not so surprising, since the air and the coolers are undoubtedly sufficiently contaminated with these yeasts."
"Onderzoeking over het Gistgeslacht Brettanomyces" by Mathieu Theodoor Jozef Custers, 1940, page 25.
I wonder if any of the commercial Lambic breweries currently use pure cultures? It wouldn't surprise me. But, unlike the Brewers' Journal text, this does state that Lambic was usually spontaneously fermented, with the infection starting in the cooler.
That was informative, wasn't it? Maybe I should look to see if I have more stuff like this about Lambic.