Congress Versus Infusion Malt Extract Methods: Which Method Is Best for Your Brewery?

Glen P. Fox (1) and Mary-Jane Maurice (2). 1. University of California, Department of Food Science & Technology, Davis, CA 95616, USA. 2. Black Frost Distilling, 201 1st Street N, New Ulm, MN 56073, USA


This review describes some of the basic differences between mashing methods used in laboratory testing and how they reflect industry mashing conditions. Two types of mashing methods are used to assess malt quality. A “soft" Congress method based on low-temperature mash-in (45°C) with a slow increase to 70°C (European Brewery Convention and American Society of Brewing Chemists methods) provides more opportunity for malt to be “modified" and could result in the malt showing better quality than how it might perform in a commercial setting. Conversely, a hot mash method (the Institute of Brewing [IoB]) uses a 65°C mash-in temperature that reduces the activity of β-​glucanase, xylanase, and the proteases while allowing the starch-degrading enzymes to have some activity. Thus, any malt tested with this mash style will quickly be shown to have good or poor quality. This mash method is more realistic for the all-malt beer styles that are currently most popular in the United States, namely India pale ales and the like. Further, to the measurement of the potential extract, these styles will produce differences in wort quality with increases or decreases in soluble nitrogen, free amino nitrogen, wort β--glucan, and viscosity based solely on the mash method. This method is also the best way to identify potential malting barley varieties in a breeding program because it quantitatively calls out the worst performers. A number of large commercial brewing companies have moved from using the Congress mash to the IoB mash, as the latter is a better indicator of true malt quality when mashing-in with high temperatures. Although this topic has been raised for several types over the last few decades, perhaps it is again time to seriously consider the most appropriate mash method to measure malt quality, particularly for the predominantly ale-focused craft brewing industry—a mash method that better reflects industry practice, supporting the needs of both the brewer and the maltster.

Keywords: enzymes, extract, gelatinization, malt, mashing​

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