Strike Temperature refers to the temperature of the hot liquor (hot brewing water) used to create the mash. Although the term is sometimes used to refer to the initial mash temperature (which may be tepid) of temperature-programmed mashes, it is more often used in reference to the British-style single-temperature infusion mash. In traditional British brewing, both mashing and lautering happen in the same vessel. Mashing grains to extract sugars requires careful management of the mash temperature because this controls the enzymatic activity that breaks down starch, proteins, and cell wall materials to create the wort.
The most suitable range of temperatures for this breakdown in traditional British infusion mashing is 60°C–70°C (140°F–158°F) because this range covers the optimal activity of the amylase starch-digesting enzymes. At the lower end of the range, a highly fermentable wort will be produced, whereas at the upper end a thicker, less fermentable wort will result. Brewers choose their mash temperature according to the character of wort required for the specific brew.
Hitting the target mash temperature is critical and is achieved by adding hot brewing liquor (water) to the grist as it enters the mash/lauter tun. The temperature of this “strike” liquor must be hotter than the target mash temperature because the malt will inevitably be at a lower temperature. Generally this strike temperature is around 75°C–80°C (167°F–176°F). Calculations are typically employed to achieve this and require a measurement of the grist temperature and an estimate of the heat losses of the process. Taking into account the strike temperature of the water, the temperature of the grist, the temperature of the room, and the temperature of the mash vessel, as well as the texture of the mash, the achievement of the desired mash temperature was once as much an art form as a science. It remains so at many small craft breweries.
Having a hotter strike temperature than the final mash temperature also assists in starch digestion because starch grains swell and gelatinize at high temperatures, thus exposing the starch to liquor for dissolving and for enzymatic breakdown.
In decoction and temperature-programmed mashes a lower strike temperature may be required because cell wall material and protein require different temperature steps for their digestion, generally 35°C–50°C (95°F–122°F) for cell walls and 45°C–50°C (113°F–122°F) for protein.