This brief section on malting explains something I'd wondered about. I've lots of late 19th-cntury analyses of Lagers and is most cases the attenuation is rubbish, rarely more than 65% apparent.
"During a discussion upon a paper on Continental Brewing Plant I read before the London Section some years ago, Mr. Chaston Chapman defined the difference between infusion and decoction brewing very concisely and epigrammatically in the expression "Malting versus Machinery," but on consideration I am inclined to modify that pithy conclusion, for an English malt will not produce a satisfactory lager beer, any more than would a lager malt yield a perfect infusion beer; wherefore one must go considerably deeper into things, to discover the reason for the great difference between the two final results.It's the malt that was to blameas it produced a less fermentable wort. Good to know.
The production of a lager malt occupies considerably less time than does one suitable for infusion beers, but it is the shortness of its growing period and the rapidity of its kiln drying that prevents that loss of nitrogenous matters and checks that development of a comparatively high diastatic capacity, characteristic of a well-made English malt, whilst it is just these qualities—which are even more accentuated in the "chit," "short grown," and other malts made on the newer systems recently suggested — as for example, the Kropff — which go to build up those vital initial factors determining the high residual extract and low alcoholic percentage of a lager beer. Here then we have the starting point of that divergence between the two beers, which divergence becomes wider and wider as the brewing process proceeds, and demonstrates the truth of the old saying that "the malt is the soul of the beer."
Journal of the Institute of Brewing, vol. XVII, 1920, pages 486 - 489.
Though it seems that the mashing scheme also contributed to the lack of fermentability:
"The next step, after having secured the right kind of malt, is to mash it on such lines as will give the correct type of wort. This, however, is best obtained by means of the three mash decoction process, which consists in mashing cold and leaving this cold mash a definite time for the enzymes to absorb the water, which they do better at a cold than at a warmer temperature.
An alternative method is to mash for an initial temperature of 100° F., at which the proteolytic enzyme is most active, and to allow the mash to remain at that temperature for a definite period, in order that it shall become slightly acidified, either naturally or by the employment of a culture of lactic acid bacterium; such acidification assisting the digestive action of the peptase, whereby much of the insoluble nitrogen is transformed into peptone. Griesmayer differentiates between peptone, which is also partly formed during kilning together with the parapeptone produced during curing on the kiln at high temperatures, and those cleavage products of gluten and fibrin origin which are the results of boiling the various portions of the mash, but to all of which he ascribes the highly nutritious properties, palate fulness, and remarkable foaming capacity characteristic of true lager
Again, by the perfect control which may be effected by boiling the various portions of the mash, the proportions of dextrin to maltose may be accurately adjusted, and refractory starch so modified, that the extract yield of a given malt is much higher when treated by the decoction process than would be obtained by infusion. This is evidenced by the comparative analyses of Infusion and Decoction grains, the approximate extracts being respectively:—
Infusion... 11.5 per cent. Decoction... 5.5 per cent.
Further, by reason of the high finishing temperature, conversion is arrested, and the type of wort fixed, whereby the degree at which attenuation shall cease, is determined.
Although the three mash method is the one originally employed in the production of lager, owing to improvements in the manufacture of the malt, certain modifications have, from time to time, been suggested, notably by Windisch, who may be regarded as the pioneer of the more rapid mashing processes, among which may be mentioned the "Schmitz" and the "Spring," all of which have the object of preventing any undue saccharification of the newer and more diastatic malts now available, at the same time saving time and fuel."
Journal of the Institute of Brewing, vol. XVII, 1920, pages 489 - 490.
A triple decoctoin was a traditional Bavarian method of mashing, the exact details of which varied from city to city. And there were also double or even single decoction mashes. Especially for Pilsner beers, methods involving less boiling were employed to keep the colour as pale as possible.
German brewers often use acidified malt to lower the pH of the wort. Not being allowed to just add lactobacillus because of the reinheitsgebot.
Decoction was a way of squeezing a reasonable yield from crap malt. There was no need to go to all that trouble with British malt, which was well enough modified to produce a good yield with a simple mashing scheme. Though it sounds from the sudden end to conversion was to deliberately create a finished beer with lots of unfermented sugars.
Lots more of this yet to come.