As can be seen from the huge amount of breweries, there is a big variety of beers and every beer has more or less its individual recipe. One can hardly find two identical brewing processes in two different breweries, which is also influenced by the personal preferences of the respective brewer. Besides variations in used raw materials such as grains, hops and yeast, there are differences in time periods and temperature ranges during the wort production. Additionally, there are various technical installations available for mashing, lautering and boiling as well as heating or cooling the wort. This leads to the fact that the detailed knowledge of the brewing process in Brewery “A” might not result in a similar knowledge of any other brewery “B”. Within the brewhouse, there is a great difference in existing mashing and boiling systems.

At the Hutt brewery, the brewing process starts with mashing by mixing crushed malt with 58°C hot water in the mash tun. Within the next two hours, the mash follows a defined time-temperature profile with various temperature rests. Therefore, the shell of the mash tun is heated by steam. The principle of mashing (heating a mixture of water and grains) is more or less the same in all breweries. The diversity is based on the starting temperature, heating rate, way of heating the mash, set temperature and time for mashing as well as the used number and types of the mash tuns.

In the next process step called ‘lautering’, the resulting liquid is separated from the grains. Besides straining the mixture, the resulting draff is washed with hot water (around 80°C), to extract additional sugars. The variety of lautering processes in terms of consumed thermal energy is relatively small compared to mashing or boiling. Main differences can be found by the used lauter tun units. The temperature and proportion of hot water for this process step are more or less in a similar range.

Afterwards, the wort boiling takes place, which is the most energy intensive process step within the brewhouse. Before the wort is boiled, it has to be pre-heated from lautering temperature (around 75°C) to boiling temperature. This can be done by different methods, such as using the boiling copper or an external heat exchanger that is fed by steam, by high pressurised hot water or by recovered heat. After pre-heating, the wort is boiled for a fixed period, while hops are added to the wort. The respective boiling time and temperature is directly linked to the desired amount of evaporated water and the installed boiling system. This leads to different boiling times for different beer recipes or breweries. Another variation during wort boiling is given by the installed heat recovery system. At the Hutt brewery, the occurring vapours are condensed to heat brewing water that is temporarily stored in a hot water tank. Based on the respective installation, the recovered heat can also be used for pre-heating of lauter wort or boiling itself. For pre-heating of lauter wort, the evaporated water is condensed and heats water in a closed heat recovery cycle to a preferably high temperature level. This water is used to heat the lauter wort with a special heat exchanger from 75°C close to boiling temperature. The second possibility, using the recovered heat for wort boiling, is realised by using a special vapour compressor (thermally or mechanically driven). The compressed vapour can be used to heat the wort during boiling with a special heat exchanger.

After boiling, the so called ‘hot trub’ (remaining solid particles) is separated from the wort within a whirlpool. The wort is pumped tangential into the whirlpool, which causes a sedimentation process. After leaving the whirlpool, the wort is cooled by a double-stage heat exchanger. At first, the wort is cooled to approximately 15°C while cold brewing water is heated to 80°C and fed to a hot water storage tank. In a second step, ice water is used to cool the wort to a temperature below 10°C. The separation within the whirlpool is rather similar in all breweries. Solely the temperature level of hot wort can vary, which is based on the respective boiling process. The heat recovery installations for wort cooling are also comparable within different breweries. Usually, the amount of produced wort is similar to the amount of brewing water, heated within wort cooling, and sufficient to cover the demand for mashing and lautering. After wort cooling, the wort production is finished and the wort leaves the brewhouse.