Hops boiling process
As described in the previous section, automatic brewing continues and the hops boiling process is started. The display again shows the time and temperature of the phase. As the target temperature of 100°C cannot always be reached, timing starts after a waiting period of 2 minutes without increase in temperature. When pressing the Select button during the automatic mode, the target temperature and target time can be corrected or changed. Wort is boiled during this phase. On the one hand, coagulable proteins are excreted and on the other hand wort is sterilised, which means that all bacteria that could potentially spoil the beer during fermentation are destroyed. As already mentioned in the description of the previous phase, the original wort can be adjusted by means of evaporated water or by topping up water. Hops is also added during the boiling period of 80-90 minutes, which imparts the required bitterness as well as the aroma to the beer. Depending on the recipe and taste, the amount of hops added can vary. Once the wort sample at the end of the previous phase has been measured in terms of original wort, it is set by means of the liquid level. Where the original wort content is equal to the target value, the level must be maintained right to the end by topping up boiling water. Where the original wort is too high, the wort is diluted by topping up with water and increasing the liquid level correspondingly. Care must be taken to replace evaporating water as well. Conversely, the liquid level must be decreased (through water evaporation) if the original wort content is too low, which leads to a higher concentration of sugar in the wort and consequently also to a higher alcohol content in the beer. It is essential that the boiling phase in the brewing vessel is performed without a lid. This prevents the wort from boiling over, but more importantly, it is also necessary for the hops boiling process to ensure that all unwanted aromatic substances can evaporate from the hops, as they would otherwise impact negatively on the taste of the beer.
Adding hops originally also served to better preserve the beer. Acoustic signals will be sounded for the batches of hops to signal the times that are programmed into the recipe. Depending on the type of hops and bitter substance content, add the first batch of hops to the boiling wort 10 to 15 minutes after boiling has started. The hops remains in the wort during the entire boiling period, as its substances only begin to unfold their effect after boiling for some time, thereby imparting the intended hops bitterness to the beer. The resins and oils in the hops are also released, which then ultimately gives the wort its malt flavour. You can then add another batch of hops approx. 10 min before the end of the boiling period, which merely adds to the flavour. Additional excretion of bitter substances is no longer possible in the remaining time. The type of hops, quantity, and the number of hops batches differ according to the recipe and type of beer being brewed. You may program three hops batches. Hops can be added in the form of pellets or dried hop blooms. The bitter substance content in beers is indicated in bitter units (BU) and is around 10-20 BU in wheat beers and 25-45 BU in Pilsners.
The bitter substance content of hops is indicated in % alpha acid, which can be between 2-4% (approx. 8% in pellets). The following formula can be used to calculate the hops quantity:
A bitter substance concentration of 30% can be assumed for a total boiling period of 80-90 minutes
Example:
A volume of 20l of wheat beer with a bitter substance content of 15 BU is to be brewed. The hops available has an alpha acid content of 3%. Thus, the following hops quantity is derived, which is added at the beginning of the boiling process. The hops added shortly before the end of the boiling process is not included in this calculation, as no more noteworthy bitter substance amounts are imparted to the wort in this short period of time.
Once the boiling time has elapsed, another signal tone is emitted, indicating the end of the brewing procedure. Use the Select button to acknowledge it. The heating switches off.