Table of Contents
Review: “Are the days of Congress mashing over?”
David Evan Evans and John M. Brauer
The operating parameters chosen for the small-scale mash to determine malt quality are critical in defining malt quality. These key malt quality parameters include extract, attenuation, Kolbach Index (KI), wort FAN, viscosity, β-glucan, colour etc. The Congress mash (45 °C – 30 min, 0.2 mm grist grind, 1:4 grist : water, ramp to 70 °C (1 °C/min), rest 25 – 60 min, lautering at 1:9 G:W ratio, RT) is currently the industry agreed small-scale mashing protocol for malt quality analysis. The Congress protocol appears to have its origins from a German Brewers Convention in Vienna in 1815, later formalized in 1907. As such, the Congress mash was developed to assess the malts of the time that were less modified and homogenous than before the innovations of malting engineers Nicholas Galland and Charles Saladin (c1870 – 1890) that ushered in modern pneumatic malting production. Prof Martina Gastl (TUM, Germany) concluded that the Congress mash favours cytolytic (and proteolytic) modification compared to modern mashing practice that mash in at 60 – 65 °C which favours amylolytic modification. Prof Barry Axcell (South African Breweries Ltd., RSA), among others, critiqued malt quality analysis for providing brewers with inferior practical information with respect to high gravity brewing, lautering, attenuation, foam, flavor and colloidal stability. Central to improving malt quality analysis was a complete revaluation of the small scale mashing protocol. This review sequentially considers what the likely optimum parameters are. The review concludes that potential starch hydrolysis into fermentable sugars is best determined by mashing in at 65 °C for 60 min (compromise between starch gelatinization and DP enzyme thermostability), a grist grind of 0.7 mm (possibly 0.4 mm), addition of 1.4 mM Ca2+ (56 ppm Ca2+), a 1:3 grist:water ratio (higher gravity) and mash out temperature of 78 °C which is broadly in line with modern commercial brewing practice. For small-scale practical convenience and efficiency, ‘lautering’ at 1:9 G:W ratio and at RT, as with the Congress mash was preserved. Comparison of this style of mash shows broad agreement (correlation) with the Congress mash for extract, attenuation, wort FAN, KI, β-glucan and protein, however the ranking of samples is substantially different. This perspective is important for brewers, but critical for malting barley breeders whose selection indices between candidate breeding lines are largely based on agronomic and quality rank to provide improved resolution between high malting quality progeny.
Descriptors: Malt quality, small-scale mashing, malting barley breeding
BrewingScience, 77 (May/June 2024), pp. 33-49
