often referred to as HWE, is an analytical measure derived on a laboratory scale of the quantity of dissolved solids derived from malt or other materials used in the brewhouse. Hot water extract analysis is used to measure the brewing value of different malts or adjuncts and can be used to compare cereal varieties and malting processes. See adjuncts. It is used by brewers to compare malts and maltsters and as a measure to ensure malt delivered to a brewery is within a defined specification. Measurement of hot water extract is obtained by measuring the specific gravity of wort derived from a fixed weight of malt (or other material) that is ground in a specified manner at a fixed temperature for a specific time period. This process broadly mimics the mashing process in a brewery. See mashing. The wort is filtered, the specific gravity measured, and the hot water extract of the sample calculated.

The methods for measuring hot water extract are specifically laid down by the three main brewing institutions, the Institute of Brewing and Distilling in the UK (IOB), the European Brewing Convention (EBC), and the American Society of Brewing Chemists (ASBC). Each method reflects the brewing methods predominantly used in their area, for example, the IOB analysis involves mixing and holding the malt at 65.5°C, reflecting infusion mashing of ale-style beers. The EBC, sometimes called “congress” mash, involves mashing at 45°C and increasing the temperature to 70°C, reflecting the process used in lager brewing. See congress mash. The system used by the ASBC is similar to the EBC method. Hot water extract is quoted in a number of ways, for example, liter degrees per kilogram of malt (e.g., 304l deg/kg); in Europe, the practice is to express the extract as a percentage of the dry weight of malt (e.g., 82%).